Betulin derived compounds useful as antiviral agents

Field of the invention

The invention relates to compounds derived from betulin, and to the use thereof as antiviral agents in applications of pharmaceutical industry. Further, the invention relates to novel betulin derivatives and methods for the production thereof either directly from betulin, or from intermediates derived therefrom.

Prior art

Betulin having the structure 1 shown below is a naturally occuring pentacyclic triterpene alcohol of the lupane family, also known as betulinol and lup-20(29)- ene-3β,28-diol. Betulin is found in the bark of some tree species, particularly in the birch (Betula sp.) bark at best in amounts up to 40 % of the bark dry weight. In addition to betulin, also minor amounts of compounds related to betulin are obtained from tree bark. There are known methods mainly based on extraction for the isolation of betulin from bark material.

1

In some applications, poor solubility of betulin causes problems with respect to use and formulation, and accordingly, betulin is converted to its derivatives to improve solubility. In the production of said derivatives, reactivities of the functional groups of betulin, that is, the primary and secondary hydroxyl groups and the double bond are typically utilized. Both hydroxyl groups may be esterifϊed,

thus obtaining mono- or diesters. Glycoside derivatives may be produced from betulin using known procedures, and betulin may be subjected to oxidation, reduction and rearrangement reactions in the presence of a suitable oxidation reagent, reducing reagent, or an acid catalyst, respectively.

Betulinic acid having the structure 3 shown in the reaction scheme below may be isolated e.g. from birch (Betula sp.) bark or cork of cork oak (Quercus suber L.) by extraction, and further, it may be produced by several methods mainly based on direct oxidation of betulin or birch bark material. The reaction scheme shows the direct oxidation of betulin 1 as Jones oxidation according to US 6,280,778 in the presence of a chromium (VI) oxide catalyst to give betulonic acid 2, followed by the selective reduction of the betulonic acid 2 thus obtained with sodium boro- hydride to give betulinic acid 3.

An alternative process for the production of betulinic acid is disclosed in US 5,804,575, comprising an oxidation step where the 3-beta-hydroxyl of betulin is protected by acetylation. Isomerization and oxidation of the secondary hydroxyl group of betulin is thus prevented.

Suitability of betulin and the derivatives thereof for medical and cosmetic applications and for industrial chemicals is known to some extent.

Acitivity of betulin and compounds derived therefrom as antiviral agents is relatively poorly studied. No betulin derived compound, or more generally, no compound with a triterpene structure is commercially available as an antimicrobial drug. Antiviral activities of betulin, betulinic acid, and betulonic acid as well as some derivatives thereof against the following viruses have been investigated: human immunodeficiency virus (HIV) belonging to retroviruses; influenza A virus; viruses of the Herpes simplex type I (HSV-I); influenza virus FPV/Rostock; EC-HO-6 enterovirus.

Clear antiviral activity against the herpes virus {Herpes simplex type I) was found for betulin, and betulinic and betulonic acids. Activity against HSV-I was considerably increased by the introduction of different groups of ureido type to betulonic acid at C-28 thereof, as described in Bioorg. Med. Chem. Lett. 13 (2003) 3549- 3552. Interestingly, it was found that an anti-HIV compound, DSB, which is par- ticularly effective against retroviruses, has no effect on HSV-I virus, as described in Antimicrob. Agents Chemother. 45 (2001) 1225-1230.

As for betulin and betulinic acid, no activity on the influenza virus (FPV/Rostock) was found, whereas weak antiviral activity was seen for betulonic acid as dis- cussed in Fitoterapia 74 (2003) 489-492. On the other hand, the 3-oxime of betulonic acid is a more potent compound against the influenza A vims than betulinic acid. Once the carboxy group at C-28 was replaced with a primary amide group, the EC ₅₀ value was altered to 0.7 μM as described in the scientific article Bioorg. Med. Chem. Lett. 13 (2003) 3549-3552. Moreover, 3,28-dioximebetulin was found to have slight antiviral activity against influenza A viruses, and ECHO-6 virus. Activity against the ECHO-6 virus was found for betulin and betulinic and betulonic acids as described in Fitoterapia 74 (2003) 489-492, and Pharm. Chem. J. 36 (2002) 303-306.

Further, activities against retroviruses and particularly against human immunodeficiency virus (HIV) of some compounds of the 3-O-(3,3-dimethylsuccinyl)

betulinic acid type have been investigated. Once an aminoalkane side chain was introduced to a betulinic acid derivative having a 3,3-dimethylsuccinyl side chain, very considerable anti-HIV activity was found as described in Antimicrob. Agents Chemother. 48(2004) 663 - 665.

The document US 5,750,587 discloses the antiviral activity of betulin and derivatives thereof, particularly against Herpes simplex virus (HSV). These viruses belong to the group of double stranded DNA viruses.

Activities of several betulin derivatives on HIV-I virus have been evaluated to provide efficient medicaments as alternatives to present preparations due to toxicity, side effects, and high price thereof, as well as due to resistant HIV strains. HIV viruses are lentiviruses, i.e. a subgroup of retroviruses. According to I-Chen Sun et al. in J. Med. Chem. 1998, 41, 4648-4657, activity against HIV has been shown for mono- and disuccinic acid and glutarate esters of betulin.

The document US 6,172,110 discloses the activities of betulin and dihydrobetulin acyl derivatives against HIV when used alone or in combination with other anti- HIV drugs or immunomodulators.

The document WO 2006/053255 presents anti-retroviral betulin derivatives for the treatment of HIV infection, and for the prevention of transmission of the infection to a fetus from a pregnant infected mother.

There is an increasing need for novel safe antiviral compounds worldwide due to problems of frequent infections by both known and new viruses. Considerably increased travelling and mobility of people all over the world contribute to spreading of virus infections more rapidly and efficiently than before.

There are several types of viruses classified either to DNA or RNA viruses according to the nucleic acid thereof. Typical and therapeutically interesting RNA

viruses causing illnesses in humans include picornaviruses (polio) rheo- and myxoviruses (influenza), paramyxoviruses, and rabdo- and togaviruses (rubella). On the other hand, therapeutically interesting DNA viruses causing illnesses in humans include adenoviruses, papovaviruses, herpesviruses, and poxviruses.

In the present drug treatment, antiviral drugs are classified into antiviral drugs against herpes viruses, against retroviruses, and to other antiviral drugs. Antiviral drugs against herpes viruses are divided into two subgroups: nucleoside derivatives (aciclovir, valaciclovir, genciclovir, penciclovir, and famciclovir), and to other anti -herpesvirus drugs (phoscarnet). Anti-retrovirus (anti-HIV) drugs are subdivided into two classes: inhibitors of the reverse transcriptase enzyme of the virus, and inhibitors of the HIV protease. Said inhibitors of the reverse transcriptase enzyme of the virus are further subdivided into nucleoside derivatives (zidovudine, zalcitabine, didanocine, stavudine, lamivudine, abavirine), and other compounds than those with nucleoside structures (nevirapine, efavirenz, delavir- idine). Inhibitors of HIV protease include sacinavir, indinavir, ritonavir, nelphi- navir, and amprenavir. Other antiviral drugs include amantadine, ribavirine, zanamivir, and various interferons.

Compounds used as antiviral drugs have typical undesired side effects. Use of nucleoside derivatives as antiviral drugs against herpesvirus is reported to be associated with disorders in the gastrointestinal tract, excema and headache, whereas bone marrow damages and disorders of the central nervous system, CNS, are additionally reported with ganciclovir. Renal toxicity and disorders of the cen- tral nervous system are found as side effects of phoscarnet. Peripheral neuropathy, pancreatitis, diarrhea, stomachache, hepatitis and excema are found for drugs against retroviruses and particularly for inhibitors of the viral reverse transcriptase used as anti-HIV drugs. Typical reported side effects for the inhibitors of the HIV protease include diarrhea, stomachache, nausea, elevation of hepatic enzymes, lipide activities, and hyperglycemia, and further the formation of urinary calculus for indinavir. As side effects of other antiviral drugs, disorders of the gastrointes-

tinal tract and symptoms of the CNS have been reported for amantadine; hemolysis, anemia, bone marrow damages, and irritated mucous membranes for ri- bavirine; flu-like symptoms for zanamivir; and flu-symptoms and cachexy for interferons.

Alphaviruses are positively stranded RNA viruses belonging to the subfamily of arboviruses or Togaviridae family of viruses spread by Arthropods. Alphaviruses are mainly spread by mosquitoes and cause pyretic arthritis, or even lethal encephalitis depending on the virus.

Sindbis virus belonging to alphaviruses, spread through Eurasia and Africa causes rash and arthritis, so-called Pogosta disease (Carelian fever) in Finland, Scandinavia, and e.g. South Africa. Virus strains isolated in Carelia, Sweden, and Africa are very similar, and migratory birds are believed to play a role in the spreading of the viral strains. Incidence time of the disease, august-september, suggests that mosquitoes of late summer maturing about in the middle of July (Culex and Cu- lisetd) act as vectors. Mosquitoes serving as vectors of the virus mainly feed on avian blood, birds being a favourable host of the virus.

O'nyong-nyong virus spread by mosquitoes also belongs to alphaviruses. Said virus appeared in 1959 in Africa infecting over 3 million people, the symptoms of the infection being rash, fever and articular disorders.

Alphaviruses may also cause encephalitis such as Western, Eastern and Venezue- Ian equine encephalitis, (WEE), (EEE), and (VEE), respectively. As evident from the names of the diseases, also horses are affected. On the contrary, natural hosts thereof, the birds, carry the infection without any symptoms. From the birds, the virus errs to a horse or human with fatal consequences; the virus is not adapted to such a host. EEE is the most dangerous to but also luckily the rarest in humans, VEE being the mildest of these infections normally causing fever, affecting only one per cent of patients with encephalitis. WEE is dangerous in children, 20 % of

the patients being younger that 1 year. In one third of the patients, the WEE infection results in permanent damage of the central nervous system.

Semliki Forest virus (SFV) occuring in Africa also belongs to alphaviruses. Gen- erally, the SFV is not pathogenic in humans, and thus it is widely used as a model in virus research and in studies directed to the functions of host cells.

On the basis of the above it is clear that there is an obvious need for novel and safe antiviral agents, particularly anti-alphavirus agents.

Betulin and betulinic acid are in water sparingly soluble compounds that may be emulsified and/or formulated only with difficulty, and poorly converted into preparations for pharmaceutical industry. Thus, there is additionally an obvious need to provide environmentally acceptable novel betulin derivatives having an improved emulsifiability and/or solubility in water or in solvents or media typically used in pharmaceutical applications, said derivatives also being very suitable for the production of stable preparations with desired activities.

Compounds derived from betulin refer here to pentacyclic triterpenoids, particu- larly to betulonic acid and betulin derivatives and particularly to those betulin derivatives comprising as substituents natural compounds and/or compounds with known low toxicity, and especially to alcohol, phenol and/or carboxylic acid and/or ester and/or amide and/or ether derivatives of betulin and/or derivatives having a partial heterocyclic structure and/or carbamate derivatives.

Antiviral compounds refer here to compounds with activity against viruses.

Objects of the invention

An object of the invention is the use of compounds derived from betulin as antiviral agents, particularly as agents against alphaviruses.

Another object of the invention is also the use of compounds derived from betulin as active antiviral agents, especially as agents against alphaviruses, particularly in medical applications.

Still another object of the invention is to provide novel betulin derivatives useful as antiviral agents, particularly as agents against alphaviruses.

Further, another object of the invention is to provide novel betulin derivatives useful as active antiviral agents, especially as agents against alphaviruses, particu- larly for medical applications referring here to drugs to be administered both to humans and to animals.

Another object of the invention is to provide novel betulin derivatives comprising known naturally occuring compounds, pharmacophoric heterocyclic moieties and/or compounds with low toxicity as substituents.

Morover, another object of the invention is to provide novel betulin derivatives having improved solubilities and/or emulsifiabilities in water and/or in solvents or media typically used in cosmetic and medical applications such as fats, oils, alco- hols and the like.

Yet another object of the invention is to provide methods for producing said novel betulin derivatives.

Still another object of the invention is the use of said novel betulin derivatives as antiviral agents, particularly as agents against alphaviruses.

Another object of the invention is to provide compositions comprising said novel betulin derivatives.

Further, another object of the invention is the use of betulonic acid as an antiviral agent, particularly as an agent against alphaviruses.

Another object of the invention are compositions comprising betulonic acid.

Characteristic features of the betulin compounds, the use thereof, and the compositions and production methods according to the invention are disclosed in the claims.

General description of the invention

The present invention is directed to the use of compounds derived from betulin, particularly novel betulin derivatives, and betulonic acid as antiviral agents, particularly as agents against alphaviruses. Said compounds are particularly suitable for pharmaceutical applications for humans and animals.

The invention is further directed to novel betulin derivatives preferably comprising as substituents natural compounds and/or known compounds with low toxicity, such as to alcohol, phenol and/or carboxylic acid and/or ester and/or amide and/or ether derivatives of betulin and/or derivatives with heterocyclic structural moieties and/or carbamate derivatives, particularly to carboxylic acid and ester and amide derivatives of betulin and/or derivatives with partial heterocyclic structures and/or carbamate derivatives. The invention is also directed to the use of betulin derivatives as active agents having improved solubilities and/or emulsifi- abilities in solvents or media used in pharmaceutical industry, and further to methods for the production of said betulin derivatives.

Detailed descriprion of the invention

It was surprisingly found that some compounds derived from betulin, and also some novel betulin derivatives and betulonic acid have antiviral activities, particu-

larly activities against alphaviruses. Several compounds useful according to the invention comprise as substituents natural compounds, compounds with pharma- cophoric heterocyclic moieties and/or known compounds with low toxicities, said inventive compounds thus being safe and environmentally acceptable.

According to the invention, it is also possible to produce novel betulin derivatives potent as active agents, particularly carboxylic acid and ester and amide derivatives of betulin and/or derivatives comprising heterocyclic structural moieties and/or carbamate derivatives, several of the derivatives having improved solubil- ity and/or emulsifiability in solvents and media used in pharmaceutical industry.

It was also surprisingly found that the active agent is released in a controlled manner for an extended time by some compounds derived from betulin. This allows for efficient specified administration of the products of the invention.

It was also surprisingly found that also betulonic acid 2 may be used as a potent active agent according to the invention.

According to the invention, compounds derived from betulin acting as efficient antiviral agents, particularly as agents against alphaviruses, include the following compounds derived from betulin having the general formula I shown below, and pharmaceutically acceptable salts thereof, where in formula I

Rl = H, -OH, -ORa, -0(C=O)R _b , -NR ₃ R _z , -CN, -CHO, -(C=O)OR ₃ , -SR ₃ , -0(C=O)NHR ₃ , =0 or =S where R ₃ , R _b and R _z independently represent H, C ₁ -C ₂₂

aliphatic, unbranched or branched, saturated or unsaturated hydrocarbon residue; C ₃ -C ₈ cyclic or heterocyclic residue; substituted or unsubstituted phenyl or benzyl residue; amine, amide or amino acid; substituted or unsubstituted 1,2,3-triazol, 1,2,4-triazol, tetrazol, pyrrole, isoxazol, pyrazol, imidazol, or oxazol; a carboxy- methyl, carboxymethylester or carboxymethylamide derivative or a salt thereof;

R2 = -CH ₂ OH, -CH ₂ ORa, -CH ₂ 0(C=0)R _b , -(C=O)ORb ₅ -CH ₂ NR _a R _z , -CH ₂ CN, -CH ₂ CHO, -CH ₂ (C=O)OR ₈ , -CH ₂ SR _a , -CH ₂ O(C=O)NHR ₃ , -CH=O or -CH=S where R _a , R _b and R _z independently represent H, Ci-C ₂₂ aliphatic, unbranched or branched, saturated or unsaturated hydrocarbon residue; C ₃ -C ₈ cyclic or heterocyclic residue; substituted or unsubstituted phenyl or benzyl residue; 1,2,3-triazol, 1,2,4-triazol, tetrazol, pyrrole, isoxazol, pyrazol, imidazol, or oxazol, being unsubstituted or optionally substituted with an amine, amide or amino acid; a car- boxymethyl, carboxymethylester or carboxymethylamide derivative or a salt thereof;

R3 = isopropenyl, isopropyl, isopropylphenyl, isopropylhydroxyphenyl, or iso- propylsuccinic acid derivative or a salt thereof;

Xi ₀ = X ₁₁ = H, C or N;

Xi2 = Xi ₃ = "absent"; (C=O)OR, (C=O)NHR where R = H or a C _r C ₆ linear or branched alkyl or alkenyl group or substituted or unsubstituted phenyl or benzyl residue or X ₁₂ -Xi ₃ forms a cyclic partial structure of the form -(X ₁₂ =X _H )-X _I5 - (X ₁₃ =X ₁₆ )- where X ₁₂ = Xi ₃ = C, Xi ₄ = Xi ₆ = "absent", O or S, Xi ₅ = C, O, S or N- X ₁₇ where X ₁₇ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, substituted or unsubstituted phenyl or benzyl residue;

a, b, c and d independently represent a double or single bond; and e = "absent" or represents a double or single bond; and

According to the invention, preferable compounds derived from betulin include the compounds having the following structures IA - IQ:

IA: Rl = OH;

R2 = CH ₂ O(C=O)R _f or -CH ₂ OR _a (C=O)OR _f where R _f = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, Ci-C ₂₂ linear or branched alkyl or alkenyl group and R _a = Ci-C ₂₂ linear or branched alkylene or alkenyl group; R3 = CH ₂ =CCH ₃ (isopropenyl group);

Xi ₀ = Xn - H;

XI ₂ = XB = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IB:

Rl = OH;

R2 = CH ₂ O(C=O)(CHRg)CH ₂ COOY where R _g = C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, Y = H, Na, K, Ca, Mg, Ci-C ₄ -alkyl group, or NR _h where R _h = H or Ci-C ₄ -alkyl group;

R3 = CH ₂ =CCH ₃ ;

Xi2 = Xi3 = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IC:

Rl = OH;

R2 = CH ₂ ORj where Rj = ester with ornithine, N-acetylanthranilic acid or trimethylglycine (or betain ester); R3 = CH ₂ =CCH ₃ ;

Xio - X] I - H;

X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

ID:

Rl = OH;

R2 = CH ₂ O(C=O)CHRj(NHZ) or -CH ₂ OR _a (C=O)NHRj where R _a = C ₁ -C ₂₂ linear or branched alkylene or alkenyl group; R _j = H, C ₁ -C ₄ -alkyl, benzyl, A- hydroxybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl or 3-indolylmethyl group, and Z = H, R _k , (C=O)Rk or COORk where R _k = Ci-C ₂₂ branched or un- branched alkyl or alkenyl group, or a phenyl, benzyl or 4-hydroxybenzyl group;

R3 = CH ₂ =CCH ₃ ;

X ₁₀ = Xπ = H; X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IE: Rl = OH;

R2 = CH ₂ OR _n where R _n = an ester of carboxymethoxy substituted verbenol, terpi- neol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid; R3 = CH ₂ =CCH ₃ ; XiO = Xn = H; Xi ₂ = Xi ₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IFa:

Rl = O(C=O)R _m or -OR _a (C=O)OR _m where R _m = C ₃ -Cs cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, C]-C ₂₂ linear or branched alkyl or alkenyl group and R _a = CpC ₂₂ linear or branched alkenyl or alkylene group;

R2 = CH ₂ O(C=O)R ₀ or -CH ₂ OR _a (C=0)R ₀ where R ₀ = C ₃ -Cs cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, Ci-C ₂₂ linear or branched alkyl or alkenyl group and R _a = CpC ₂₂ linear or branched alkenyl or alkylene group; R3 = CH ₂ =CCH ₃ ; Xi ₂ = Xi ₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent"

IFb:

Rl = 0(C=O)(CHR _c )CH ₂ COOY where R _c = CpC ₂₂ linear or branched alkyl or alkenyl group, Y = H, Na, K, Ca, Mg, Ci-C ₄ alkyl group or NRj ₁ where Rj, = H or a C ₁ -C ₄ alkyl group; R2 = CH ₂ O(C=O)(CHR _d )CH ₂ COOY where R _d = CpC ₂₂ linear or branched alkyl or alkenyl group, Y = H, Na, K, Ca, Mg, CpC ₄ alkyl group or NR _k where R _k = H or a CpC ₄ alkyl group; R3 = CH ₂ =CCH ₃ ; X ₁₀ ⁼ Xπ ⁼ H; Xi ₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IFc: Rl = OR _r where R _r = an ester of ornithine, N-acetylanthranilic acid, or trimethyl- glycine;

R2 = CH ₂ ORp where R _p = an ester of ornithine, N-acetylanthranilic acid, or trimethylglycine; R3 = CH ₂ =CCH ₃ ; X ₁₀ - Xu = H; X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IFd: Rl = 0(C=O)CHRs(NHZ) or -0R _a (C=0)NHR _s where R _a = C ₁ -C ₂₂ linear or branched alkenyl or alkylene group; R ₈ = H, CrC ₄ -alkyl, benzyl, 4-hydrozybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂₅ 4-imidazolylmethyl or 3-indolylmethyl group, Z = H, R _k , (C=O)R _k or COOR _k where R^ = C ₁ -C ₂₂ branched or unbranched alkyl or alkenyl group, or a phenyl, benzyl or 4-hydroxybenzyl group; R2 = CH ₂ O(C=O)CHR _x (NHZ) or -CH ₂ 0R _a (C=0)NHR _x where R _a = C-C ₂₂ linear or branched alkenyl or alkylene group; R _x = H, Q-Gi-alkyl, benzyl, 4- hydrozybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl or 3-indolylmethyl group, Z = H, R _y , (C=O)Ry or C00R _y where R _y = Ci-C ₂₂ branched or unbranched alkyl or alkenyl group, or a phenyl, benzyl or 4-hydroxybenzyl group; R3 = CH ₂ =CCH ₃ ; X ₁₀ = X ₁₁ = H; X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IFe:

Rl = OR _V where R _v = an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifo- lol, globulol, epiglobulol, sedrol, or episedrol, each being carboxymethoxy substi- tuted, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid;

R2 = CH ₂ OR _u where R ₁₁ = an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolon- gifolol, globulol, epiglobulol, sedrol, or episedrol, each being carboxymethoxy substituted, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid; R3 = CH ₂ =CCH ₃ ; X ₁ O = Xn = H; X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IG:

Rl = OH;

R2 = (C=O)NHCHR _x COOY where Y = H, Na, K, Ca, Mg, C ₁ -C ₄ alkyl group or

NRy where R _y = H or a C ₁ -C ₄ alkyl group, and R _x = H, C ₁ -C ₄ -alkyl, benzyl, 4- hydrozybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl or 3-indolylmethyl group or L-aspartate, L-histidine, L-glutamine or L-lysine; R3 = CH ₂ =CCH ₃ ; X ₁₀ = Xn = H; Xi2 = Xi3 = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IH:

Rl = OH; R2 = (C=O)R _W where R _w = an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol;

R3 = CH ₂ =CCH ₃ ;

XiO = Xn ⁼ H; X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and

e = "absent".

Ha:

Rl = OR where R = H, C ₁ -C ₄ alkyl, benzyl, 4-hydroxybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl, 3-indolylmethyl, or CH ₃ SCH ₂ group, or an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, e- piglobulol, sedrol, or episedrol, each being carboxymethoxy substituted, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid; R2 = (C=O)NHCHR _x COOY where Y = H, Na, K, Ca, Mg, Ci-C ₄ alkyl group or

NRy where R _y = H or a C ₁ -C ₄ alkyl group, and R _x = H, Ci-C ₄ -alkyl, benzyl, 4- hydrozybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂₅ 4-imidazolylmethyl or 3-indolylmethyl group or L-aspartate, L-histidine, L-glutamine or L-lysine;

R3 = CH ₂ =CCH ₃ ; X ₁₀ = X ₁₁ = H;

Xi ₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

lib:

Rl = OR where R = H, C ₁ -C ₄ alkyl, benzyl, 4-hydroxybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂₅ or CH ₃ SCH ₂ group, or an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol, each being carboxymethoxy substituted, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid;

R2 = (C=O)R _W where R _w = OH, an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol; R3 = CH ₂ =CCH ₃ ; X ₁ O = Xu = H;

X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IJa:

Rl = oxo(=O) group;

R2 = (C=O)NHCHR _x COOY where Y = H, Na, K, Ca, Mg, C ₁ -C ₄ alkyl group or

NR _y where R _y = H or a C ₁ -C ₄ alkyl group, and R _x = H, Ci-C ₄ -alkyl, benzyl, A- hydrozybenzyl, CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl or 3-indolylmethyl group or 28-aspartatedimethyl ester;

R3 = CH ₂ =CCH ₃ ;

Xio ⁼ Xii - H;

Xi ₂ = Xi ₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IJb:

Rl = oxo(=O) group;

R2 = (C=O)R _W where R _w = OH, an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol;

R3 = CH ₂ =CCH ₃ or CH ₃ -CH-CH ₃ ;

X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IK:

Rl = OH or 0-(C=O)R _b where Rb = C ₃ -Cg cyclic or heterocyclic residue, substi- tuted or unsubstituted phenyl or benzyl residue, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group;

R2 = CH ₂ OH or CH ₂ O-(C=O)R _f where R _f = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, Ci-C ₂₂ linear or branched alkyl or alkenyl group;

R3 = (CH ₃ ) ₂ CR _Z or CH ₃ CHCH ₂ R ₂ where R _z = C ₆ H _5-0 (OH) _n or C ₆ H _5-11 - _m (0H) _n (0CH ₃ ) _m and n = 0-5, m = 0-5, n + m < 5;

X ₁₀ = X ₁₁ = H;

X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IL:

Rl = OH or 0-(C=O)R _b where R _b = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, Ci-C ₂₂ linear or branched alkyl or alkenyl group; R2 = CH ₂ OH or CH ₂ O-(C=O)R _f where R _f = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, Cj-C ₂₂ linear or branched alkyl or alkenyl group;

R3 = H ₂ C=CCH ₂ R _q or CH ₃ CCH ₂ Rq where R _q = succinic anhydride, succinic im- ide or CH(COOR _O )CH ₂ COOR _Z where R ₀ = H, Na, K, Ca, Mg or a Ci-C ₂₂ linear or branched alkyl or alkenyl group and R ₂ = H, Na, K, Ca, Mg or a Ci-C ₂₂ linear or branched alkyl or alkenyl group;

Xio " Xn ⁼ H;

X ₁₂ = X ₁₃ = "absent"; a, b, c, and d each represent a single bond; and e = "absent".

IM:

Rl = H, OR _z , 0(C=0)R _b , NR _a R _z , CN, =N0R _a , CHO, (C=O)OR ₂ , SR ₂ , =0, =S where R _z = H, Cj-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ shown below, and R _a = H, CpC ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or

alkenyl group, or an aromatic group ZZ, or Rl corresponds to the partial structure XX shown below;

R2 = CH ₂ OR _Z , CH ₂ O(C=O)Rb, (C=O)OR _b , CH ₂ NR _a R _z , CH ₂ CN, CN, CH=NOR ₃ , CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, Cj-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci- C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R2 corresponds to the partial structure YY shown below; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ (isopropyl group); X ₁₂ = Xi ₃ = "absent"; a, b, c, and d independently represent a single or a double bond; and e - "absent"; said partial structures XX and YY where YY = CH ₂ XX are selected from the group consisting of:

1,2,3-triazoles isoxazoles

1 ,2,4-triazoles pyrazoles

f \ tetrazoles R' Tr R" imidazoles

py ^rroles oxazoles in which structures R, R', and R" independently represent H, an aromatic group ZZ, Cj-C ₆ linear or branched alkyl or alkenyl group; the aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a C ₁ -C ₆ linear or branched alkyl or alkenyl group, a Ci-C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hydroxy or trifluoromethyl

IN:

Rl = H, OR _Z , NRaRz, CN, CHO, (C=O)OR ₂ , 0(C=0)R _b , 0(C=O)NHRf, SR ₂ , =0, =S where R ₂ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and Rf = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or R _f corresponds to the partial structure YX shown below;

R2 = CH ₂ OR ₂ , (C-O)ORb, CH ₂ NR ₉ R ₂ , CH ₂ CN, CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ O(C=O)Rb, CH ₂ O(C=O)NHRf, CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, Cj-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, C _J -C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and R _f = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or R _f corresponds to the partial structure YX shown below; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; X ₁₀ = Xn = H;

Xi2 = Xi3 = "absent"; a, b, c, and d independently represent a single or a double bond; and e = "absent";

said aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a Cj-C ₆ linear or branched alkyl or alkenyl group, a C ₁ -C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hydroxy or trifluoromethyl group; and the partial structure R _f or R _b is of the form YX:

X ₁ X ₂ X ₃ X ₄ where R4 = H or a C ₁ -C ₂₀ linear or branched alkyl or alkenyl group, or an aromatic group ZZ;

X ₅ = "absent", C, O, N, or S;

Xi-X ₂ forms a cyclic partial structure of the form:

Xi-(X ₃ =Xe)-X ₇ -(X ₄ =Xs)-X ₂ where X] = X ₂ = C orN;

X ₃ = X ₄ = C;

X ₆ = X ₈ = O, S or "absent";

X ₇ = C, O, S, or N-X ₉ where X ₉ = H, Cj-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; and f = a single or a double bond

IO:

Rl = H, OR ₂ , NR ₈ R ₂₅ CN, CHO, (C=O)OR ₂ , 0(C=0)R _b , 0(C=0)NHR _f , SR ₂ , =0, =S where R _z = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R ₃ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or

an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and R _f = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or R _f corresponds to the partial structure YX shown below; R2 = CH ₂ OR ₂ , (C=O)OR _b , CH ₂ NR _a R _z , CH ₂ CN, CH ₂ CHO ₃ CH ₂ (C=O)OR ₂ , CH ₂ O(C=O)R _b , CH ₂ O(C=O)NHR _f , CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R ₃ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and R _f = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or R _f corresponds to the partial structure YX shown below; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; X ₁₀ ⁼ Xn = H; X ₁₂ = X ₁₃ = "absent"; a, b, c, and d independently represent a single or a double bond; and e = "absent"; and said aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a Ci-C ₆ linear or branched alkyl or alkenyl group, a Ci-C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hydroxy or trifluoromethyl group; and the partial structure Rf or Rb is of the form YX:

where R4 = H or a C ₁ -C ₂₀ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; X ₅ = "absent", C, O, N, or S; X ₁ = X ₂ = C or N; and X ₃ = X ₄ = R _g5 (C=O)OR _g or (C=O)NHR ₆ where R _g = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group; and f = a single or a double bond

IP: Rl = H, OR, NR ₃ Rz, CN, CHO, (C=O)OR ₂ , O(C=O)R _b , 0(C=O)NHR ₂ , SR ₂ , =0, =S where R ₂ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and Rb = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; R2 = CH ₂ OR ₂ , (C=O)OR _b , CH ₂ NR ₃ R ₂ , CH ₂ CN ₅ CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ O(C=O)Rb, CH ₂ O(C=O)NHR ₂ , CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; and said aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a Ci-C ₆ linear or branched alkyl or alkenyl group, a Ci-C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hydroxy or trifluoromethyl group; and at X ₁₀ -Xn, a cyclic or heterocyclic partial structure having the form X ₁ O-(XIa=XiO-Xi ₅ -(XiS=XIe)-Xn:, where

-xr _/ -1

12 - λ-13 - C,

X ₁₄ = X ₁₆ = O ₃ S or "absent";

X ₁₅ = C, O, S, or N-X ₁₇ where X ₁₇ = H, a Ci-C ₆ linear or branched alkyl or al- kenyl group, or an aromatic group ZZ; and a, b, c, d and e independently represent double or single bonds

IQ:

Rl = H, OR ₂ , NR _a R _z , CN, CHO, (C=O)OR ₂ , O(C=O)R _b , 0(C=O)NHR ₂ , SR ₂ , =0, =S where R ₂ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ ₅ and R _a = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ;

R2 = CH ₂ OR ₂ , (C=O)ORb, CH ₂ NR _a R ₂ , CH ₂ CN, CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ O(C=O)Rb, CH ₂ O(C=O)NHR ₂ , CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R ₃ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; and said aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a C ₁ -C ₆ linear or branched alkyl or alkenyl group, a C]-C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fiuoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hydroxy or trifluoromethyl group; and at X _1O -Xn, a novel cyclic or heterocyclic partial structure may be present where Xi ₀ =XiI = C or N;

X ₁₂ = X ₁₃ = R ₅ (C=O)OR or (C=O)NHR where R = H or a Cj-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and a, b, c, d and e independently represent double or single bonds.

Preferable compounds derived from betulin for the preparation of antiviral drugs, particularly drugs against alphaviruses for humans and animals include Diels- Alder adduct of jσ-methyl-4-phenylurazole, Diels-Alder adduct of m-nitro-4- phenylurazole, Diels-Alder adduct of 3-chloro-4-phenylurazole, betulinic aldehyde, betulin 28-oxime, 28-ήitrile of betulin 3-acetoxime, 20,29-dihydrobetulonic acid, isostearic acid diester of betulin, octanoic acid diester of betulin, octanoic acid 28-monoester of betulin, betulin, betulin-28-monoacetate, 28-acetate of betu- lonic alcohol, betulonic acid, betulin 3,28-diacetate, betulin 3,28-diacetate-18,19- ene, Diels-Alder adduct of 4-phenylurazole, betulinic acid, betulin 18,19-epoxy- 3,28-diacetate, 28-aspartateamide dimethylester of betulonic acid, Diels-Alder adduct of 4-methylurazole, betulonic aldehyde, 28-tetrahydropyranyl ether of betulin, betulin 3-acetate-28-tetrahydropyranyl ether, betulin 3-acetate, betulin 3- acetate-28-mesylate, betulin 28-Cig-alkenylsuccinic acid ester, betulin 28- nicotinate.

Particularly preferable compounds derived from betulin for the preparation of antiviral drugs, particularly drugs against alphaviruses for humans and animals include Diels-Alder adduct of p-methyl-4-phenylurazole, Diels-Alder adduct of m-nitro-4-phenylurazole, Diels-Alder adduct of 3-chloro-4-phenylurazole, betulinic aldehyde, 20,29-dihydrobetulonic acid, octanoic acid diester of betulin, betu- Hn, betulin-28-monoacetate, 28-acetate of betulonic alcohol, betulonic acid, betulin 3,28-diacetate, Diels-Alder adduct of 4-phenylurazole, betulin 18,19-epoxy- 3,28-diacetate, betulonic aldehyde, 28-tetrahydropyranyl ether of betulin, betulin 3-acetate-28-tetrahydropyranyl ether, betulin 3-acetate.

Novel compounds derived from betulin according to the invention useful as antiviral agents, particularly as agents against alphaviruses include betulin derivatives

of the general formula I and pharmaceutically acceptable salts thereof, where in formula I

Rl = H, -ORa, -O(C=O)R _b , -NR ₃ Rz ₅ -CN, -CHO, -(C=O)OR ₃ , -SR ₃ , -0(C=O)NHRa, ⁼ 0 or =S where R _a , R _b and R _z independently represent H, C ₁ -C ₂₂ aliphatic, unbranched or branched, saturated or unsaturated hydrocarbon residue, with the proviso that X ₁₀ = X ₁₁ is not H; C ₃ -C ₈ cyclic or heterocyclic residue; substituted or unsubstituted phenyl or benzyl residue; substituted or unsubstituted

1,2,3-triazol, 1,2,4-triazol, tetrazol, pyrrole, isoxazol, pyrazol, imidazol, or oxazol; a carboxymethyl, carboxymethylester or carboxymethylamide derivative or a salt thereof;

R2 = -CH ₂ OR ₃ , -CH ₂ O(C=O)Rb, -(C=O)ORb, -CH ₂ NR ₃ R ₂ , -CH ₂ CN, -CH ₂ CHO, - CH ₂ (C=O)OR ₃ , -CH ₂ SRa, -CH ₂ O(C=O)NHR ₃ , -CH=O or -CH=S where R ₃ , R _b and R _z independently represent H, C ₁ -C ₂₂ aliphatic, unbranched or branched, saturated or unsaturated hydrocarbon residue, with the proviso that Xio = Xn is not H; C ₃ -C ₈ cyclic or heterocyclic residue; substituted or unsubstituted phenyl or benzyl residue; substituted or unsubstituted 1,2,3-triazol, 1,2,4-triazol, tetrazol, pyrrole, isoxazol, pyrazol, imidazol, or oxazol; a carboxymethyl, carboxy- methylester or carboxymethylamide derivative or a salt thereof;

R3 = isopropenyl, isopropyl, isopropylphenyl, isopropylhydroxyphenyl, or iso- propylsuccinic acid derivative or a salt thereof;

X ₁₀ = X ₁₁ = H ₅ C OrN;

X ₁₂ = X ₁₃ = "absent"; (C=O)OR, (C=O)NHR where R = H or a C ₁ -C ₆ linear or branched alkyl or alkenyl group or substituted or unsubstituted phenyl or benzyl residue or X ₁₂ -X ₁₃ forms a cyclic partial structure of the form -(XI ₂ =X _H )-X _I5 - (X ₁₃ =X ₁₆ )- where X ₁₂ = X ₁₃ = C, Xi ₄ = Xi ₆ = "absent", O or S, Xi ₅ = C, O, S or N- Xi ₇ where Xi ₇ = H ₃ Ci-C ₆ linear or branched alkyl or alkenyl group, substituted or unsubstituted phenyl or benzyl residue;

a, b, c and d independently represent a double or single bond; and

e = "absent" or represents a double or single bond.

In case Xio = Xn = H, Xn = X ₁₃ = "absent", a, b, c and d each represent a single bond and e = "absent", then Rl, and R _a and R _z present in R2 independently represent a Ci-C ₂₂ aliphatic, unbranched or branched, saturated or unsaturated hydro- carbon residue with the proviso that at the same time Rl represents =0 (oxo) or =S; C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl residue, substituted or unsubstituted 1,2,3-triazol, 1 ,2,4-triazol, tetrazol, pyrrole, iso- xazol, pyrazol, imidazol, or oxazol, a carboxymethyl, carboxymethylester or car- boxymethylamide derivative or a salt thereof.

In a preferable embodiment of the invention, Rl = OH, R2 = CH ₂ O(C=O)R _f or -CH ₂ OR _a (C=O)OR _f where R _f = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl residue, R _a = C ₁ -C ₂₂ linear or branched alkenyl or al- kylene group, R3 = CH ₂ =CCH ₃ , Xi ₀ = Xj ₁ = H, X ₁₂ = Xi ₃ = absent; a, b, c, and d each represent a single bond, and e = "absent".

In another preferable embodiment of the invention, Rl = OH, R2 = CH ₂ O(C=O)(CHRg)CH ₂ COOY where R _g = C ₄ -C ₂₂ linear or branched alkyl or alkenyl group, Y = H, Na, K, Ca, Mg, CrQ-alkyl group, or NR _h where R _h = H or Ci-C ₄ -alkyl group, R3 = CH ₂ =CCH ₃ , X ₁₀ = X _n = H, X ₁₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OH, R2 = CH ₂ OR; where Rj = an ester of ornithine, TV-acetylanthranilic acid or trimethylglycine; R3 = CH ₂ =CCH ₃ , X ₁₀ = Xn = H, Xi ₂ = Xi ₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OH, R2 = CH ₂ O(C=O)CHRj(NHZ) or -CH ₂ OR ₃ (C=O)NHRJ where R _a = Cj -C ₂₂ linear or branched alkylene or alkenyl group; R _j = CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4- imidazolylmethyl or 3-indolylmethyl group, and Z = H, R _k , (C=0)R _k or COOR _k where R _k = Ci-C ₂₂ branched or unbranched alkyl or alkenyl group, or a phenyl, benzyl or 4-hydroxybenzyl group, R3 = CH ₂ =CCH ₃ , X ₁₀ = Xu = H, Xi ₂ = Xi ₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OH, R2 = CH ₂ OR _n where R _n - an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globu- lol, epiglobulol, sedrol, or episedrol, each being carboxymethoxy substituted, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid, R3 = CH ₂ =CCH ₃ , Xio = Xπ = H, Xi ₂ = Xi ₃ = absent, a, b, c, and d each represent a single bond; and e = absent.

In still another preferable embodiment of the invention, Rl = 0(C=O)R _n , or

-OR _a (C=O)OR _m where R _m = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, R ₃ = Ci-C ₂₂ linear or branched alkylene or alkenyl group; R2 = CH ₂ O(C=O)R ₀ or -CH ₂ OR ₃ (C=O)R ₀ where R ₀ = C ₃ -C ₈ cyclic

or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, R _a = C ₁ -C ₂₂ linear or branched alkylene or alkenyl group, R3 = CH ₂ =CCH ₃ , Xio = Xu = H, X ₁₂ = X ₁₃ = absent, a, 'b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = 0(C=O)(CHR ₀ )CH ₂ COOY where R _c = C ₄ -C ₂₂ linear or branched alkyl or alkenyl group, Y = H, Na, K, Ca, Mg, C ₁ -C ₄ alkyl group or NRi ₁ where R _h = H or a C ₁ -C ₄ alkyl group; R2 = CH ₂ O(C=O)(CHR _d )CH ₂ COOY where R _d = C ₄ -C ₂₂ linear or branched alkyl or alkenyl group, Y = H, Na, K, Ca, Mg, Cj-C ₄ alkyl group or NR _k where R _k = H or a C ₁ -C ₄ alkyl group, R3 = CH ₂ =CCH ₃ , X ₁₀ = Xn = H, X _ϊ2 = Xi ₃ = absent, a, b, c, and d each represent a single bond, and e = "absent".

In still another preferable embodiment of the invention, Rl = OR _r where R _r = an ester of ornithine, N-acetylanthranilic acid, or triniethylglycine, R2 = CH ₂ ORp where R _p = an ornithine ester, an ester of N-acetylanthranilic acid, or a trimethyl- glycine ester, R3 = CH ₂ =CCH ₃ , Xi ₀ = Xn = H, X ₁₂ = Xi ₃ = absent, a, b, c, and d each represent a single bond, e = absent.

In still another preferable embodiment of the invention, Rl = 0(C=O)CHR _s (NHZ) or -0R _a (C=0)NHR _s where R _a = C ₁ -C ₂₂ linear or branched alkenyl group; R _s = CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl or 3-indolylmethyl group, Z = H, R _k , (C=O)R _k or COOR _k where Rk = Ci-C ₂₂ branched or unbranched alkyl or alkenyl group, or a phenyl, benzyl or 4-hydroxybenzyl group, R2 = CH ₂ O(C=O)CHR _x (NHZ) or -CH ₂ 0R _a (C=0)NHR _x where R _a = Ci-C ₂₂ linear or branched alkenyl group; R _x = CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl or 3- indolylmethyl group, Z = H, R _y , (C=O)Ry or COOR _y where R _y = Ci-C ₂₂ branched or unbranched alkyl or alkenyl group, or a phenyl, benzyl or 4-hydroxybenzyl group, R3 = CH ₂ =CCH ₃ , Xj ₀ = Xn = H, X ₁₂ = Xi ₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OR _V where R _v = an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcu- min, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol, each being carboxymethoxy substituted, or an ester of chry- santhemic acid, cinnamic acid, or retinolic acid, R2 = CH ₂ OR ₁ , where R ₁₁ = an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcu- min, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol, each being carboxymethoxy substituted, or an ester of chry- santhemic acid, cinnamic acid, or retinolic acid, R3 = CH ₂ =CCH ₃ , X ₁₀ = X ₁₁ = H, X ₁₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OH, R2 = (C=O)NHCHR _x COOY where Y = H, Na, K, Ca, Mg, Cj-C ₄ alkyl group or NR _y where R _y = H or a C ₁ -C ₄ alkyl group, and R _x = CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4- imidazolylmethyl or 3-indolylmethyl group, R3 = CH ₂ =CCH ₃ , X] ₀ = Xn = H, Xi ₂ = Xi ₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OH, R2 = (C=O)R _W where R _w = an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol, R3 = CH ₂ =CCH ₃ , X ₁₀ = X ₁₁ = H, Xi ₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OR where R = H, C ₁ -C ₄ alkyl, benzyl, 4-hydroxybenzyl, -CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4- imidazolylmethyl, 3-indolylmethyl, or CH ₃ SCH ₂ group, or an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol, each being carboxymethoxy substituted, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid, R2 = (C=O)NHCHR _x COOY where Y = H, Na, K, Ca, Mg, C ₁ -C ₄ alkyl group or NR _y where R _y = H or a Cj-C ₄ alkyl group, and R _x =

-CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolylmethyl or 3-indolylmethyl group, R3 = CH ₂ =CCH ₃ , X ₁₀ = Xi ₁ = H, X ₁₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OR where R = H, C ₁ -C ₄ alkyl, benzyl, 4-hydroxybenzyl, -CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , or CH ₃ SCH ₂ group, or an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epi- globulol, sedrol., or episedrol, each being carboxymethoxy substituted, or an ester of chrysanthemic acid, cinnamic acid, or retinolic acid, R2 = (C=O)R _W where R _w = an ester of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epi- globulol, sedrol, or episedrol, R3 = CH ₂ =CCH ₃ , Xj ₀ = X _n = H, Xi ₂ = Xi ₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = oxo group (=0), R2 = (C=O)NHCHR _x COOY where Y = H, Na, K, Ca, Mg, Ci-C ₄ alkyl group or NR _y where R _y = H or a C ₁ -C ₄ alkyl group, and R _x = -CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4- imidazolylmethyl or 3-indolylmethyl group, or L-aspartate, L-histidine, L- glutamine, L-lysine, or 28-aspartate dimethylester, R3 = CH ₂ =CCH ₃ , Xio = Xn = H, Xi ₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = oxo group (=0), R2 = (C=O)R _W where R _w = an ester of verbenol, terpineol, thymol, carvacrol, men- thol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol, R3 = CH ₂ =CCH ₃ , Xj ₀ = Xu = H, Xj ₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OH or 0-(C=O)R _b where R _b = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phe-

nyl or benzyl residue, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, R2 = CH ₂ OH or CH ₂ O-(C=O)R _f where R _f = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue; Ci-C ₂₂ linear or branched alkyl or alkenyl group or a phenyl group, R3 = (CH ₃ ) ₂ CR _Z or CH ₃ CHCH ₂ Rz where R _z = C ₆ H _5-0 (OH) _n or C ₆ H _5-n-m (OH) _n (OCH ₃ ) _m and m = 0-5, n = 0-5, n + m < 5, X ₁₀ = X ₁ , = H, X ₁₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = OH or 0-(C=O)R _b where R _b = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or unsubstituted phenyl or benzyl residue, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, R2 = CH ₂ OH or CH ₂ O-(C=O)R _f where R _f = C ₃ -C ₈ cyclic or heterocyclic residue, substituted or un substituted phenyl or benzyl residue, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, R3 = H ₂ C=CCH ₂ Rq or CH ₃ CCH ₂ Rq where R _q = succinic anhy- dride, succinic imide or CH(COOR ₀ CH ₂ COOR _Z where R ₀ = H, Na, K, Ca, Mg or a C ₁ -C ₂₂ linear or branched alkyl or alkenyl group and R _z = H, Na, K, Ca, Mg or a C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, X ₁₀ = Xn = H, Xi ₂ = X ₁₃ = absent, a, b, c, and d each represent a single bond, and e = absent.

In still another preferable embodiment of the invention, Rl = H, OR ₂ , 0(C=O)R _b , NR _a R _z , CN, =N0R _a , CHO, (C=O)OR ₂ , SR ₂ , =0, =S where R _z = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ shown below, and R _a = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, C _1O -C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or Rl corresponds to the partial structure XX shown below; R2 = CH ₂ OR ₂ , CH ₂ O(C=O)Rb ₃ (C=O)OR _b , CH ₂ NR ₃ R ₂ , CH ₂ CN, CN, CH=NOR ₃ , CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ SR ₂ , CH=O, CH=S where R _z = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R ₃ = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and Rb = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R2 corresponds to the partial structure YY shown below, with the proviso that Rl or R2 comprises

the group ZZ or XX; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ (isopropyl group); X ₁₀ = X ₁₁ = H;X ₁₂ = X ₁₃ = absent, a, b, c, and d independently represent a single or a double bond; and e = absent; said partial structures XX and YY where YY = CH ₂ XX being selected from the group consisting of:

1 ,2,3-triazoles oxazoles

1 ,2,4-triazoles pyrazoles

tetrazoles imidazoles

pyrroles oxazoles in which structures R, R ¹ , and R" independently represent H, an aromatic group ZZ, C ₁ -C ₆ linear or branched alkyl or alkenyl group; and the aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a C ₁ -C ₆ linear or branched alkyl or alkenyl group, a C ₁ -C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hydroxy or trifluoromethyl group.

In still another preferable embodiment of the invention, Rl = H, OR ₂ , NR _a R _z , CN, CHO, (C=O)OR ₂ , 0(C=O)R _b , 0(C=O)NHRf, SR ₂ , =0, =S where R _z = H, Ci-C ₆

linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ ₅ and R _b = H, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and R _f = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or R _f corresponds to the partial structure YX shown below; R2 = CH ₂ OR ₂₅ (C=O)OR _b , CH ₂ NR _a R _z , CH ₂ CN, CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ 0(C=0)R _b , CH ₂ O(C=O)NHR _f , CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ ₅ and R _a = H ₅ C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and R _f = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or R _f corresponds to the partial structure YX shown below, with the proviso that Rl or R2 comprises the group ZZ or YX; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; X ₁₀ = X ₁₁ = H, X ₁₂ = X ₁₃ = "absent"; a, b, c, and d independently represent a single or a double bond; and e = "absent"; said aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H ₅ a C ₁ -C ₆ linear or branched alkyl or alkenyl group, a Ci-C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hydroxy or trifluoromethyl group; and the partial structure R _f or R _b is of the form YX:

where R4 = H or a C ₁ -C ₂₀ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; X ₅ = "absent", C, O, N ₅ or S; X ₁ -X ₂ forms a cyclic partial structure of the form: X ₁ -(X ₃ =Xg)-X ₇ -(X ₄ =Xg)-X ₂ where X ₁ = X ₂ = C or N; X ₃ = X ₄ = C; X ₆ = X ₈ = O ₅ S or "absent"; X ₇ = C, O, S ₅ or N-X ₉ where X ₉ = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; and f = a single or a double bond.

In still another preferable embodiment of the invention, Rl = H, OR _Z , NR ₃ R ₂ , CN, CHO, (C=O)OR ₂₅ 0(C=O)R _b5 0(C=O)NHR _f5 SR ₂ , =0, =S where R _z = H ₅ Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ ₅ and R ₈ = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and Rb = H ₅ Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and R _f = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or Rf corresponds to the partial structure YX shown below; R2 = CH ₂ OR ₂ , (C=0)0R _b , CH ₂ NR _a R _z , CH ₂ CN ₅ CH ₂ CHO ₅ CH ₂ (C=O)OR ₂₅ CH ₂ O(C=O)R _b , CH ₂ O(C=O)NHR _f , CH ₂ SR _Z , CH=O, CH=S where R ₂ = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, or R _b corresponds to the partial structure YX shown below, and R _f = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ or R _f corresponds to the partial structure YX shown below; with the proviso that Rl or R2 comprises the group ZZ or YX; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; Xio = Xn = H; Xj ₂ = Xi ₃ = "absent"; a, b, c, and d independently represent a single or a double bond; e = "absent"; said aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a Ci-C ₆ linear or branched alkyl or alkenyl group, a C ₁ -C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hy- droxy or trifluoromethyl group; and the partial structure R _f or R _b is of the form YX:

where R4 = H or a C ₁ -C _2O linear or branched alkyl or alkenyl group, or an aromatic group ZZ; X ₅ = "absent", C, O, N, or S; X ₁ = X ₂ = C or N; and X ₃ = X ₄ = R _g , (C=O)ORg or (C=0)NHR _g where R _g = H, C]-C ₆ linear or branched alkyl or alkenyl group; and f = a single or a double bond.

In still another preferable embodiment of the invention, Rl = H, OR, NR _a R _z , CN, CHO, (C=O)OR ₂ , 0(C=O)R _b , 0(C=0)NHR _z , SR ₂ , =0, =S where R ₂ = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; R2 = CH ₂ OR ₂ , (C=O)OR _b , CH ₂ NR ₃ R ₂ , CH ₂ CN, CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ O(C=O)R _b , CH ₂ O(C=O)NHR ₂ , CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, Cj-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _a = H, Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, C _J -C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; with the proviso that Rl or R2 comprises the group ZZ; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; and ZZ being of the form:

where R5, R6 and/or R7 may be H, a C ₁ -C ₆ linear or branched alkyl or alkenyl group, a C ₁ -C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hy- droxy or trifiuoromethyl group; at X _1O -Xi ₁ , a cyclic or heterocyclic partial structure having the form Xio-(Xi ₂ =Xi ₄ )-Xi5-(Xi3=X ₁₆ )-Xπ may be present where X] ₀ =Xii = C or N; X ₁₂ = X ₁₃ = C; X ₁₄ = Xi ₆ = O, S or "absent"; X ₁₅ = C, O, S, or N- X ₁₇ where X ₁₇ = H, a Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; and a, b, c, d and e independently represent double or single bonds.

In still another preferable embodiment of the invention, Rl = H, OR _Z , NR ₃ R ₂ , CN, CHO, (C=O)OR ₂ , 0(C=O)R _b , 0(C=O)NHR ₂ , SR ₂ , =0, =S where R ₂ = H, Cj-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R ₃ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, Ci-C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; R2 = CH ₂ OR ₂ , (C=O)OR _b , CH ₂ NR ₃ R ₂ , CH ₂ CN, CH ₂ CHO, CH ₂ (C=O)OR ₂ , CH ₂ 0(C=0)R _b , CH ₂ O(C=O)NHR ₂ , CH ₂ SR ₂ , CH=O, CH=S where R ₂ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R ₃ = H, C ₁ -C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ, and R _b = H, C ₁ -C ₂₂ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; with the proviso that Rl or R2 comprises the group ZZ; R3 = CH ₂ =C-CH ₃ or CH ₃ -CH-CH ₃ ; and said aromatic group ZZ being of the form:

where R5, R6 and/or R7 may be H, a Ci-C ₆ linear or branched alkyl or alkenyl group, a C ₁ -C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ - C ₆ alkyl or alkenyl group, halogen (fluoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylenedioxy group, sulfate, cyano, hy-

droxy or trifluoromethyl group; and at Xi ₀ -Xn, a novel cyclic or heterocyclic partial structure may be present where Xi ₀ =Xn = C or N; Xi ₂ = Xi ₃ = R, (C=O)OR or (C=O)NHR where R = H or a Ci-C ₆ linear or branched alkyl or alkenyl group, or an aromatic group ZZ; and a, b, c, d and e independently represent double or single bonds.

The novel synthetic compounds based on the structure of a pentacyclic triterpene, betulin, potentially have therapeutically significant antiviral activities.

Substituents present in the novel betulin derivatives defined above are often derived from naturally occuring substances or known compounds with low toxicity, or both, or said substituents are typical heterocyclic pharmacophoric moieties. Several of these compounds derived from betulin are environmentally acceptable compounds having only weak potential negative effects on the user and environ- ment, said negative effects being also more predictable that those of synthetic compounds. Decomposition of compounds derived from betulin typically yields betulin or acid derivatives thereof, and further, constituents of substituents. Decomposition pathways of constituents, such as natural substances, present as structural moieties in the compounds and products thus generated are well known. Moreover, the toxicity of betulin derivatives is low as demonstrated by the cytotoxicity studies performed in the examples below.

Among the compounds derived from betulin, considerable antiviral activity was found e.g. for Diels-Alder adduct of p-methyl-4-phenylurazole, Diels-Alder ad- duct of m-nitro-4-phenylurazole, Diels-Alder adduct of 3-chloro-4-phenylurazole, betulinic aldehyde, 20,29-dihydrobetulonic acid, octanoic acid diester of betulin, betulin, betulin-28-monoacetate, 28-acetate of betulonic alcohol, betulonic acid, betulin 3,28-diacetate, Diels-Alder adduct of 4-phenylurazole, betulin 18,19- epoxy-3,28-diacetate, betulonic aldehyde, 28-tetrahydropyranyl ether of betulin, betulin 3-acetate-28-tetrahydropyranyl ether, and betulin 3-acetate already at a concentration of 50 μM, as shown by the examples.

Preferable novel compounds include Diels-Alder adduct of />-methyl-4- phenylurazole, Diels-Alder adduct of rø-nitro-4-phenylurazole, Diels-Alder adduct of 3-chloro-4-phenylurazole, 20,29-dihydrobetulonic acid, octanoic acid diester of betulin, Diels-Alder adduct of 4-phenylurazole, betulin 3-acetate-28- tetrahydropyranyl ether.

Here, compounds of the invention also refer to salts, and particularly pharmaceutically acceptable salts thereof. Pharmaceutically acceptable salts are obtained from compounds of the invention and betulonic acid by known methods using bases or acids.

In accordance with the invention, pharmaceutical compositions may be prepared from compounds derived from betulin, and betulonic acid to be administered to humans or animals suffering from a viral infection, particularly an alphaviral in- fection, or to humans or animals carrying the virus without symptoms, or for the prevention of potential alphaviral infections.

An antiviral composition may be formulated from the compounds derived from betulin defined above, said compositions comprising from 0.01 to 80 % weight of at least one compound derived from betulin, and optionally one or more substances selected from adjuvants and excipients. As adjuvants and excipients, substances known in pharmaceutical products and industry may be used. Suitable excipients include alcohols, polyols, and polyol esters, various gels and fats, vegetable oils and solid excipients not hazardous to health such as starch, chitosan and cellulose and derivatives thereof, kaolin, talcum, and the like. Suitable vegetable oils include arachis, mandelic, soybean, corn, wheat germ, sesamseed, poppy seed, rapeseed, colza, tall, sunflower, palm, and olive oils.

The compositions may be formulated by methods known in the art e.g. into tab- lets, capsules, suspensions, powders, cremes, emulsions, gels, injectable preparations, sprays, and the like. The present compounds derived from betulin may be

emulsified, dissolved, or mixed in water, or in adjuvants and excipients used in the art using known mixing and production processes and additives such as surfactants, emulsifying agents, dispersants, and solvents, optionally while heating.

Particularly betulin derivatives of the invention having alkyl groups with long chains as substituents have a superior emulsifiability and/or solubility and/or mis- cibility in water or alcohols, polyols or polyol esters, various gels and fats, or vegetable oils or fatty acid derivatives thereof.

One or more compound(s) derived from betulin are administered as a suitable daily dose of 0.005 to 5 g.

Formulations may be administered through oral, topical, cutaneous, subcutaneous, intramuscular, or intravenous routes, and further, they may contain pharmaceuti- cally acceptable adjuvants, additives, solvents and vehicles known in the art.

The betulin derivatives to be used according to the invention are typically biodegradable in nature like betulin.

The solution according to the invention has several advantages. Being nontoxic, the betulin derivatives defined above are very suitable in therapeutic application for mammals. The compounds are biodegradable leaving no detrimental decomposition residues in nature. In addition, the compounds affect only the targeted organisms very specifically. According to the desired application, the selectivity and decomposition rate of the agent may be controlled by substituents of betulin. If necessary, a compound decomposing more slowly, releasing the active component during decomposition, may be prepared, resulting in a uniform activity for a longer time or so-called "modified/controlled release" activity.

Substituents present in the novel betulin derivatives defined above are often derived from naturally occuring substances or known compounds with low toxicity,

or both, or said substituents are typical heterocyclic pharmacophore moieties. Several of these compounds derived from betulin are environmentally acceptable compounds having only weak potential negative effects on the user and environment, said negative effects being also more predictable that those of synthetic compounds. Decomposition of compounds derived from betulin typically yields betulin or acid derivatives thereof, and further, constituents of substituents. Decomposition pathways of constituents, such as natural substances, present as structural moieties in the compounds and products thus generated are well known. Moreover, the toxicity of betulin derivatives is low as demonstrated by the cyto- toxicity studies performed in the examples below.

Here, compounds of the invention also refer to salts, and particularly pharmaceutically acceptable salts thereof. Pharmaceutically acceptable salts are obtained from compounds of the invention and betulonic acid by known methods using bases or acids.

Betulin derivatives of the invention described above may be produced by methods I - XIV presented below.

Method I

Betulin esters of the type IB or IFb described above may be produced by reacting 1 mol of betulin with 0.8 - 1.5 moles, preferably 1 - 1.2 moles of a C ₄ -C ₂₂ alkyl or alkenyl derivative of maleic anhydride in the presence of imidazole (1 - 7 moles, preferably 3 - 5 moles), and a solvent at 0 to 100 ⁰ C, preferably at 20 to 70 °C, for 5 to 100 hours, preferably 10 to 50 h. C ₁₈ alkenyl succinic anhydride (ASA) is preferably used. ' N-methyl-2-pyrrolidon (NMP), N ₁ N- dimethylformamide (DMF), dimethylsulfoxide (DMSO), 1,4-dioxane, diethyl ether, tetrahydrofuran (THF), acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons or mixtures thereof, preferably NMP, may serve as the solvent. After completion of the reaction, the reaction mixture is allowed to cool to room temperature, followed by separation of the product for instance by pouring the

mixture into water, decanting, dissolving in a solvent, and then if necessary, washing the product with a diluted hydrochloric acid solution and water. The solvent is removed e.g. by evaporation to dryness, thus yielding desired betulin ester as the crude product that may be purified by crystallization, chromatography, or prefera- bly by extraction using diethyl ether, tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxy ethane, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons or mixtures thereof as the solvent. Esters corresponding to the structure IFb are obtained as the main product in case an excess of anhydride (1.6 to 5 moles, preferably 2 to 2.5 moles) is used, while the use of 1 to 1.2 moles of the anhydride yields esters corresponding to the structure IB.

Method II

Betulin esters having structures of types IA, IC, ID, IE, IFa, IFc, IFd, and IFe described above may be produced from betulin (1 mol) and carboxylic acids (0.8 to 1.5 moles, preferably 1 to 1.2 moles) in the presence of N,7V~dimethylamino pyridine (DMAP) (0.01 to 1 mol) and dicyclohexyl carbodiimide (DCC) (0.8 to 1.5 moles, preferably 1 to 1.2 moles), or N-(3-dimethylaminopropyl)-iV- ethylcarbodiimide hydrochloride (EDC) (0.8 to 1.5 moles, preferably 1 to 1.2 moles) and a solvent, by agitating at 0 to 60 ⁰ C, preferably at 20 to 40 °C for 2 to 50 hours, preferably for 5 to 25 hours. The carboxylic acid is selected for different compound types as follows: IA: HO(C=O)Rj where Rj = Cu-C ₂₂ linear or branched alkyl or alkenyl group; IC: ornithine, nicotine, JV-acetylanthranilic acid or trimethylglycine; ID: HO(C=O)CR _x (NHR _y ); R _x = alkyl, heteroalkyl, or arylal- kyl group; R _y = H or acyl group; and IE: a carboxymethoxy derivative of verbe- nol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or episedrol; or chrysantliemic acid, cinnamic acid, or retinolic acid. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1 ,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably dichloromethane, may serve as the solvent. After completion of the reaction, the reaction mixture is poured into water, organic layer is sepa-

rated, followed by removing the solvent for instance by evaporation to dryness, thus yielding betulin ester as the crude product that may be purified if necessary by crystallization, chromatography, or extraction, preferably by extraction. Use of 0.8 to 1.5 moles of the carboxylic acid reagent results in compounds having the structures IA, IC, ID, IE or IFd while use of an excess of the carboxylic acid reagent (1.6 to 3 moles, preferably 2 to 2.5 moles) with dicyclohexyl carbodiimide (DCC) (1.6 to 3 moles, preferably 2 to 2.5 moles), or with _V-(3- dimethylaminopropyl)-iV-ethylcarbodiimide hydrochloride (EDC) (1.6 to 3 moles, preferably 2 to 2.5 moles) yields compounds corresponding to structures IFa, IFc, IFd, or IFe. For the production of the compounds of the IE or IFe type, an acetic acid derivative of the alcohol used as starting material is first generated according to method V.

Method III Betulin esters having structures of types IA, IC, IE, IFa, IFc, and IFd described above may be produced from betulin (1 mol) with carboxylic acids (0.8 to 1.5 moles, preferably 1 to 1.2 moles) in the presence of a tetraisopropyl ortho titanate, tetrabutyl ortho titanate, /7-toluenesulfonic acid monohydrate, or pyridine-/>- toluenesulfonate catalyst (0.01 to 1 mol), or sulphuric acid or hydrochloric acid (1 to 6 %, preferably 2 to 4 %) and a solvent, by agitating at 80 to 160 °C, preferably at 100 to 140 ⁰ C for 2 to 50 hours, preferably for 4 to 25 hours. The carboxylic acid is selected for different compound types as follows: IA: HO(C=O)Ri where Ri = C ₁₁ -C ₂₂ linear or branched alkyl or alkenyl group; IC: ornithine, nicotine, N- acetylanthranilic acid or trimethylglycine; IE: a carboxymethoxy derivative of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sed- rol, or episedrol; or chrysanthemic acid, cinnamic acid, or retinolic acid. Hydrocarbons and/or chlorinated hydrocarbons, NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1 ,2-dimethoxy ethane, acetone, ethyl acetate, or mix- tures thereof, preferably toluene or xylene, may serve as the solvent. Water generated in the reaction is separated using a water separator tube, or vacuum. After

completion of the reaction, the reaction mixture is poured into water, organic layer is separated, washed if necessary with a basic aqueous solution, preferably with an aqueous NaHCO ₃ or Na ₂ CO ₃ solution, followed by removing the solvent for instance by evaporation to dryness, thus yielding betulin ester as the crude product that may be purified if necessary by crystallization, chromatography, or extraction, preferably by extraction. Use of 0.8 to 1.5 moles of the carboxylic acid reagent results in compounds having the structures IA, IC, or IE while use of an excess of the carboxylic acid reagent (1.6 to 3 moles, preferably 2 to 2.5 moles) yields compounds corresponding to structures IFa, IFc, or IFe. For the production of the compounds of the IE or IFe type, an acetic acid derivative of the alcohol used as starting material is first generated according to method V.

Method IV

Esters having structures of types IA, IC, ID, IE, IFa, IFc, IFd, and IFe described above may be produced from betulin (1 mol) and carboxylic acids (0.8 to 1.5 moles, preferably 1 to 1.2 moles), first allowed to react with oxalyl chloride or thio- nyl chloride (1 to 10 moles, preferably 1 to 4 moles) without or in the presence of a solvent, by agitating at 0 to 80 ⁰ C, preferably at 20 to 50 ⁰ C for 2 to 50 hours, preferably for 5 to 25 hours. The carboxylic acid is selected for different com- pound types as follows: IA: HO(C=O)R _f where R, = Cn-C ₂₂ linear or branched alkyl or alkenyl group; IC: ornithine, nicotine, iV-acetylanthranilic acid or trimethylglycine; ID: HO(C=O)CR _x (NHRy); R _x = alkyl, heteroalkyl, or arylalkyl group; Ry = H or acyl group; and IE: a carboxymethoxy derivative of verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, bor- neol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, or epis- edrol; or chrysanthemic acid, cinnamic acid, or retinolic acid. Hydrocarbons and/or chlorinated hydrocarbons, NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, or mixtures thereof, preferably dichloromethane, may serve as the solvent. After completion of the reaction, the solvent is removed for instance by evaporation to dryness, if necessary, followed by purification of the desired acid chloride by crystallization, chro-

matography, or extraction, preferably by extraction. The acid chloride (0.8 to 1.5 moles, perferably 1 to 1.2 moles) thus obtained is reacted with betulin (1 mol), base (0.5 to 10 moles, preferably 1 to 5 moles) such as triethyl amine, tripropyl amine, diisopropylethyl amine, preferably triethyl amine in the presence of a sol- vent, or in the presence of the DMAP catalyst (0.001 to 1 mol), pyridine and solvent, or with a base (0.5 to 10 moles, preferably 1 to 5 moles) such as triethyl amine, tripropyl amine, diisopropylethyl amine, preferably triethyl amine, and pyridine by agitating at 0 to 80 °C, preferably at 20 to 50 °C for 2 to 50 hours, preferably for 5 to 25 hours. Hydrocarbons and/or chlorinated hydrocarbons, NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1 ,2-dimethoxy ethane, acetone, ethyl acetate, or mixtures thereof, preferably dichloromethane, may serve as the solvent. After completion of the reaction, betulin amide or betulin ester product is purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary. Use of 0.8 to 1.5 moles of the acid chloride reagent results in compounds having the structures IA, IC, ID, or IE while use of an excess of the acid chloride reagent (1.6 to 3 moles, preferably 2 to 2.5 moles) yields compounds corresponding to structures IFa, IFc, IFd, or IFe. For the production of the compounds of the IE or IFe type, an acetic acid derivative of the alcohol used as starting material is first generated according to method V.

Method V

For the production of betulin derivatives having structures of the IE and IFe type according to the methods II, III or IV, and betulin derivatives having structures of the Ha and Hb type according to the method IV, an acetic acid derivative of the alcohol is first generated as follows. Acetic acid derivative is produced by mixing an alcohol (1 mol) and chloroacetic acid (0.8 to 1.5 moles, preferably 1 to 1.2 moles) in water for 1 to 7 hours, preferably for 3 to 5 hours, at 100 to 150 ⁰ C,, preferably at 120 - 130 °C, in the presence of lithium, potassium, sodium, or hydrides or hydroxides thereof (1.5 to 3 moles, preferably 1.8 to 2.2 moles), preferably sodium (Na), sodium hydride (NaH), or sodium hydroxide (NaOH). The alcohol is selected from the group consisting of verbenol, terpineol, thymol, carvacrol,

menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, and episedrol. The mixture is allowed to cool to room temperature, made acidic with concentrated hydrochloric acid, and extracter with a solvent. Hydrocarbons and/or chlorinated hydrocarbons, diethyl ether, tetrahydrofuran, 1,4-dioxane, 1 ,2-dimethoxy ethane, ethyl acetate, or mixtures thereof, preferably diethyl ether, may serve as the solvent. If necessary, the organic phase is washed with a basic aqueous solution, preferably with an aqueous NaHCO ₃ or Na ₂ CO ₃ solution. The solvent is removed for instance by evaporation to dryness, thus yielding a carboxymethoxy intermediate that may be puri- fϊed if necessary by crystallization, chromatography, or extraction, preferably by extraction.

Method VI

Derivatives of types IG, IH, II, and IJ described above may be produced from betulonic acid (1 mol) and natural alcohols (0.8 to 1.5 moles, preferably 1 to 1.2 moles), or amino acids (0.8 to 1.5 moles, preferably 1 to 1.2 moles), in the presence of a solvent and DMAP (0.001 to 1 moles) and DCC (0.8 to 1.5 moles, preferably 1 to 1.2 moles), or EDC (0.8 to 1.5 moles, preferably 1 to 1.2 moles), by agitating at 0 to 60 °C, preferably at 20 - 50 ⁰ C for 2 to 50 hours, preferably for 5 to 25 hours. For the different compound types, the alcohol is selected as follows: IH: verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epiglobulol, sedrol, and episedrol. For the different compound types, the amino acid is selected as follows: IG: HO(C=O)R ₁ where R _t = NHCHR _x COOY where Y = H, Na, K, Ca, Mg, Ci-C ₄ -alkyl group or NR _x where R _x = H, C ₁ -C ₄ -alkyl, benzyl, 4-hydroxy- benzyl, -CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4-imidazolyl methyl, 3-indolyl methyl, or CH ₃ SCH ₂ group; preferably dimethyl ester hydrochloride of aspartic acid, methyl ester hydrochloride of L-histidine, dimethyl ester hydrochloride of L-glutaminic acid, or methyl ester dihydrochloride of L-lysine. Hydrocarbons and/or chlorin- ated hydrocarbons, NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, or mixtures thereof, preferably

dichloromethane, may serve as the solvent. After completion of the reaction, the desired betulonic acid amide or ester product (of the type IJa or IJb) may be purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary. The betulonic acid amide or ester thus obtained may be reduced to the corresponding betulinic acid amide or ester product (of the type IG or IH) if desired using sodium borohydride according to US 6,280,778. After completion of the reaction, said betulinic acid amide or ester may be purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary. Betulin derivatives of the Ha and Hb type are obtained by reacting the betulinic acid amide or ester thus obtained as described in the methods II, III or IV.

Method VII

Compounds having structures of the types IG, IH, II, and IJ described above may be produced from betulonic acid (1 mol) by reacting with oxalyl chloride or thio- nyl chloride (1 to 10 moles, preferably 1 to 4 moles) without, or in the presence of a solvent by agitation at 0 to 80 ⁰ C, preferably 20 to 50 ⁰ C ₅ for 2 to 50 hours, preferably for 5 to 25 hours. Hydrocarbons and/or chlorinated hydrocarbons, NMP ₅ DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, or mixtures thereof, preferably dichloromethane, may serve as the solvent. After completion of the reaction, the desired acid chloride may be purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary. Betulonic acid chloride thus obtained from the reaction (1 mol) is reacted with an amino acid (0.8 to 1.5 moles, preferably 1 to 1.2 moles), or an alcohol (0.8 to 1.5 moles, preferably 1 to 1.2 moles), with a base such as triethyl amine, tripropyl amide diisopropyl ethyl amine, pyridine, preferably triethyl amine in the presence of a solvent, or in the presence of the DMAP catalyst (0.001 to 1 mol), pyridine and solvent, or with a base (0.5 to 10 moles, preferably 1 to 5 moles) such as triethyl amine, tripropyl amine, diisopropylethyl amine, preferably triethyl amine, and pyridine by agitating at 0 to 80 °C, preferably at 20 to 50 ⁰ C for 2 to 50 hours, preferably for 5 to 25 hours. For the different compound types, the amino acid is selected as follows: IG: HO(C=O)R _t where R _t =

NHCHR _x COOY where Y = H, Na, K, Ca, Mg ₅ d-C ₄ -alkyl group or NR _x where R _x = H, Ci-C ₄ -aIkyl, benzyl, 4-hydroxybenzyl, -CH ₂ CH ₂ CH ₂ CH ₂ NH ₂ , 4- imidazolyl methyl, 3-indolyl methyl, or CH ₃ SCH ₂ group; preferably dimethyl ester hydrochloride of aspartic acid, methyl ester hydrochloride of L-histidine, dimethyl ester hydrochloride of L-glutaminic acid, and methyl ester dihydro- chloride of L-lysine. For the different compound types, the alcohol is selected as follows: IH: verbenol, terpineol, thymol, carvacrol, menthol, cinnamic alcohol, curcumin, eugenol, borneol, isoborneol, longifolol, isolongifolol, globulol, epi- globulol, sedrol, and episedrol. Hydrocarbons and/or chlorinated hydrocarbons, NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, or mixtures thereof, preferably dichloromethane, may serve as the solvent. After completion of the reaction, the reaction mixture is washed with diluten hydrochloric acid solution and water. The solvent is evaporated to dryness, and the reaction product (of the type IJa or IJb) is purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary. The betulonic acid amide or ester product thus obtained may be reduced to the corresponding betulinic acid amide or ester product (of the type IG or IH) using sodium borohydride according to US 6,280,778. After completion of the reaction, the desired betulinic acid amide or ester is purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary. Betulin derivatives of the II type are obtained by reacting the betulinic acid amide or ester thus obtained as described in the methods II, III or IV.

Method VIII Compounds having structures of the type IK described above may be produced from betulin (1 mol) and aromatic compounds selected to have R _z = C ₆ H _5-0 (OH) _n or C ₆ H _5-n-m (OH)n(OCH ₃ ) _m and n = 0-5, m = 0-5, n + m < 5 (4 to 20 moles) as the phenol residue in the IK group, in the presenc of a polymeric acid catalyst, preferably a sulfonic acid derivative of polystyrene (0.1 to 1.5 g, preferably 0.5 to 1 g, 16 to 50 mesh) and a solvent. The reaction mixture is agitated in an inert atmosphere at 20 to 120 ⁰ C, preferably at 75 to 110 ⁰ C for 1 to 5 hours, preferably for 2

to 4 hours. Water generated in the reaction is suitably separated using water separating tube or vacuum. Hydrocarbons and/or chlorinated hydrocarbons, NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, or mixtures thereof, preferably hydrocarbons and/or chlo- rinated hydrocarbons or ether may serve as the solvent. After completion of the reaction, the mixture is allowed to cool to room temperature, filtered, the filtrate is washed with water, dried, and the solvent is separated. The betulin derivative thus obtained is purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary.

Method IX

Compounds having structures of the type IL described above may be produced from compounds having structures of the type IA or IFa prepared as described in the methods II, III, or IV, and maleic anhydride (0.8 to 10 moles, preferably 1 to 5 moles), in the presence of hydrochinone (0.05 to 0.5 moles, preferably 0.08 to 0.3 moles), and a solvent, or in a melt by heating the reaction mixture at 150 to 220 ⁰ C, preferably at 160 to 180 ⁰ C for 1 to 5 hours, preferably for 2 to 4 hours. As a solvent, hydrocarbons and/or chlorinated hydrocarbons, NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, ace- tone, ethyl acetate or mixtures thereof may be used, preferably a melt is used. After completion of the reaction, the desired product is purified by crystallization, chromatography or extraction, preferably extraction, if necessary. The maleic anhydride derivative of betulin thus obtained may be further converted into an imide or ester compound having the structure of the type IL using known methods.

Method X

Betulin derivatives with structures of the types IM, IN, IO, IP and IQ described above may be produced by reacting betulin (1 mol) in the presence of triphenyl- phosphine (0.8 to 8 moles, preferably 2 to 5 moles), 3,3-dimethylglutaric imide (0.8 to 8 moles, preferably 2 to 5 moles), diethylazo dicarboxylate solution (0.8 to 8 moles, preferably 2 to 5 moles), and a solvent by agitating at 0 to 60 °C, pref-

erably at 20 to 40 °C for 2 to 5 hours, preferably for 5 to 25 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably tetrahydrofuran, may serve as the solvent. After completion of the reaction, the precipitate formed is filtered off. The solvent is removed for instance by evaporation to dryness, thus yielding 3-deoxy-2,3-dihydro betulin as the crude product that may be purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary.

Method XI

Betulin derivatives having structures of the types IN and IO described above may be produced by reacting betulin (1 mol) with a Diels-Alder adduct (0.8 to 5 moles, preferably 1 to 2 moles), diphenylphosphoryl azide (DPPA) (0.8 to 5 moles, preferably 1 to 2 moles), and with a base, triethyl amine, tripropyl amine, diisopro- pylethyl amine, preferably triethyl amine (TEA) (0.8 to 5 moles, preferably 1 to 2 moles), in the presence of a solvent, by agitating at 0 to 150 °C, preferably 60 to 120 °C for 1 to 48 hours, preferably for 2 to 24 hours. NMP, DMF, DMSO, 1,4- dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons or mixtures thereof, prefera- bly toluene, may serve as the solvent. After completion of the reaction, the reaction mixture is washed with diluted aqueous basic solution, diluted acidic solution, water, if necessary, followed by removal of the solvent for instance by evaporating to dryness. 28-O-Diels-Alder adduct of betulin is obtained as the crude product that may be purified by crystallization, chromatography, or extrac- tion, preferably by crystallization, if necessary. Use of an excess of the Diels- Alder adduct, diphenylphosphoryl azide (DPPA) and triethyl amine (1.5 to 3 moles, preferably 2 to 2.2 moles) results in 3,28-O-Diels-Alder diadduct of betulin.

Diels-Alder adducts may be produced from a C ₅ -C ₂₂ diene acid (1 mol) that may be linear, branched, cyclic or heterocyclic comprising ο, N or S as a hetero atom,

preferably by reacting 2,4-pentadiene acid, sorbic acid, 2-furanoic acid or anthra- cene-9-carboxylic acid with a dienophile, preferably with 4-substituted triazolin- edion, maleic anhydride, N-substituted maleimide, diethylazodicarboxylate, or dimethylacetylene dicarboxylate (0.5 to 5 moles, preferably 0.8 to 2 moles) in the presence of a solvent while agitating at 0 to 150 °C, preferably at 20 to 120 ⁰ C for 1 to 48 hours, preferably for 2 to 24 hours. NMP, DMF, DMSO ₅ 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons or mixtures thereof, preferably toluene, may serve as the solvent. After completion of the reaction, the reaction mixture is washed with water, if necessary, followed by removal of the solvent by e.g. evaporation to dryness. A Diels- Alder adduct is obtained as the crude product that may be purified by crystallization, chromatography, or extraction, preferably by crystallization, if necessary.

Method XII

Betulin derivatives having structures of the types IN and IO described above may be produced by protecting the C28 hydroxyl group of betulin (1 mol) with a substituted methyl ether, substituted ethyl ether, substituted phenyl ether, silyl ether, ester, carbonate, or sulfonate using known methods, preferably with dihydropyran (DHP) (0.8 to 8 moles, preferably 1 to 2 moles), in the presence of pyridinium-p- toluene sulfonate (PPTS) (0.01 to 2 moles, preferably 0.05 to 5 moles) and a solvent while mixing at 0 to 60 °C, preferably at 20 to 40 °C for 5 to 100 hours, preferably for 12 to 48 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably dichloromethane, may serve as the solvent. After completion of the reaction, the organic phase is washed with saturated aqueous solution of a base, and with water. The solvent is e.g. removed by evaporation to dryness yielding a betulin derivative as crude product having the C28 hydroxyl group protected with substituted methyl ether, substi- tuted ethyl ether, substituted phenyl ether, silyl ether, ester, carbonate, or sulfonate, preferably with dihydropyran. The crude product, preferably betulin 28-

tetrahydropyran ether may be purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary.

Betulin derivative having the C28 hydroxyl group protected with substituted met- hyl ether, substituted ethyl ether, substituted phenyl ether, silyl ether, ester, carbonate, or sulfonate, preferably with dihydropyran (betulin 28-tetrahydropyran ether) (1 mol) and a Diels-Alder adduct (0.8 to 5 moles, preferably 1 to 2 moles) produced according to the method XI, diphenylphosphoryl azide (DPPA) (0.8 to 5 moles, preferably 1 to 2 moles), and a base, triethyl amine, tripropyl amine, diiso- propyl ethyl amine, preferably triethyl amide (TEA) (0.8 to 5 moles, preferably 1 to 2 moles) are reacted in the presence of a solvent while mixing at 0 to 150 °C, preferably at 60 to 120 °C for 1 to 48 hours, preferably 2 to 24 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, Hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably toluene, may serve as the solvent. After completion of the reaction, the reaction mixture is washed with a diluten basic solution, diluted acid solution, water, if necessary, followed by removal of the solvent e.g. by evaporation to dryness. As crude product, betulin derivative having the C28 hydroxyl group protected with substituted methyl ether, substituted ethyl ether, substituted phenyl ether, silyl ether, ester, carbonate, or sulfonate, preferably with dihydropyran, and having at C3 hydroxyl group a Diels-Alder adduct, preferably a Diels-Alder adduct of 2,4-pentadiene acid with 4-phenyl-l,2,4-triazolin-3,5-dion, is obtained. The crude product, preferably 3-O-Diels-Alder adduct of betulin 28- tetrahydropyran ether may be purified by crystallization, chromatography, or ex- traction, preferably by crystallization, if necessary.

C28 hydroxyl group of the betulin derivative having the C28 hydroxyl group protected with substituted methyl ether, substituted ethyl ether, substituted phenyl ether, silyl ether, ester, carbonate, or sulfonate, is deprotected using known meth- ods, preferably the protecting group, tetrahydropyran, of the C28 hydroxyl of the 3-O-Diels-Alder adduct of 28-tetrahydropyran ether (1 mol) is cleaved using pyri-

dinium-jc-toluene sulfonate (PPTS) (0.02 to 1 mol, preferably 0.05 to 0.5 mol) by allowing said PPTS to react while agitating at 0 to 80 ⁰ C, preferably at 20 to 40 °C for 24 to 240 hours, preferably 48 to 120 hours. NMP, DMF, DMSO ₅ 1,4- dioxane, methanol, ethanol, 1-propanol, 2-propanol, diethyl ether, tetrahydrofu- ran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably methanol or ethanol, may serve as the solvent. After completion of the reaction, the reaction mixture is diluted with an organic solvent, washed with a diluted aqueous solution of a base, diluted acidic solution, water, if necessary, followed by removal of the solvent for instance by evaporation to dryness. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetra- hydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably ethyl acetate, may serve as the solvent. Betulin 3-O-Diels-Alder adduct is obtained as crude product that may be purified by crystallization, chromatography, or extraction if necessary, preferably by crystallization.

Method XIII

Heterocyclic betulin derivatives of the types IP and IQ described above may be produced by reacting betulin (1 mol) in the presence of an anhydride (1.6 to 5 moles, preferably 2 to 2.5 moles), pyridine (DMAP) (0,01 to 1 mol), a base, pyridine, triethyl amine, tripropyl amide, diisopropylethyl amine, preferably pyridine (1 to 100 moles, preferably 20 to 50 moles), and a solvent at 0 to 100 ⁰ C, preferably at 20 to 50 °C for 5 to 100 hours, preferably 10 to 50 hours. The anhydride is preferably acetic anhydride, however, also other carboxylic an- hydrides such as propionic anhydride, phthalic anhydride, or benzoic anhydride may be used. iV-rnethyl-2-pyrrolidon (NMP), (DMF), dimethylsulfoxide (DMSO), 1,4-dioxane, diethyl ether, tetrahydrofuran (THF), acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons or mixtures thereof, preferably dichloromethane, may serve as the solvent. After completion of the reaction, the reaction mixture is washed, if necessary, with diluted hydrochloric acid solution, aqueous basic solution, and with water. Solvent is for in-

stance removed by evaporation to dryness, giving 3,28-diester of betulin, preferably 3,28-diacetate of betulin as the crude product that may be purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary.

The 3,28-diester of betulin (1 mol), preferably the 3,28-diacetate of betulin, may be isomerized to give 3/?,28-diacetoxylup-l 8-ene in the presence of hydrochloric or hydrobromic, preferably hydrobromic acid (5 to 25 %, preferably 10 to 15 %), acetic acid (25 to 60 %, preferably 35 to 50 %), acetic anhydride (5 to 30 %, preferably 10 to 20 %), and a solvent at 0 to 60 ⁰ C, preferably at 20 to 40 °C for 4 to 1200 hours, preferably for 10 to 24 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably toluene, may serve as the solvent. After completion of the reaction, the reaction mixture is washed, if necessary, with a basic aqueous solution and water, followed by re- moval of the solvent for instance by evaporation to dryness. 3/?,28-diacetoxylup- 18-ene is obtained as crude product that may be purified by crystallization, chromatography, or extraction, preferably by crystallization, if necessary.

3/?,28-diacetoxylup-l 8-ene (1 mol) may be epoxylated using hydrogen peroxide or a peracid, preferably m-chloroperbenzoic acid (mCPBA) (0.8 to 3 moles, preferably 1 to 1.5 moles) in the presence of sodium carbonate, sodium hydrogen carbonate, sodium hydrogen phosphate, potassium carbonate, potassium hydrogen carbonate, potassium hydrogen phosphate, preferably sodium carbonate (1 to 15 moles, preferably 3 to 8 moles) and a solvent while agitating at 0 to 60 °C, pref- erably at 20 to 40 ⁰ C for 0.5 to 10 hours, preferably 1 to 4 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably chloroform, may serve as the solvent. After completion of the reaction, the reaction mixture is washed, if necessary, with a basic aqueous solu- tion and water, followed by removal of the solvent for instance by evaporation to

dryness. 3y#,28-diacetoxylup-18£,19£-epoxylupane is obtained as crude product that may be purified by crystallization, chromatography, or extraction, preferably by crystallization, if necessary.

3/?,28-diacetoxyrup-18£,19£-epoxylupane (1 mol) reacts to give 3/?,28- diacetoxylupa-12,18-diene and 3/?,28-diacetoxylupa-18,21-diene in the presence of /7-toluenesulfonic acid (0.1 to 3 moles, preferably 0.3 to 1 moles) and acetic anhydride (0.5 to 5 moles, preferably 1 to 3 moles) and a solvent while agitating at 50 to 150 °C, preferably at 90 to 130 ⁰ C, for 0.5 to 12 hours, preferably for 2 to 5 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2- dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably toluene, may serve as the solvent. After completion of the reaction, the reaction mixture is washed, if necessary, with a basic aqueous solution and water, followed by removal of the solvent for instance by evaporation to dryness. 3/?,28-diacetoxylupa-12,18-diene and 3/?,28- diacetoxylupa-18,21-diene are obtained as crude product that may be purified by crystallization, chromatography, or extraction, preferably by crystallization, if necessary.

A heterocyclic Diels-Alder adduct may be produced from a mixture (1 mol) of 3/?,28-diacetoxylupa-12,18-diene and 3/?,28-diacetoxylupa-18,21-diene by reacting said mixture with a dienophile, preferably with 4-substituted triazolindion, maleic anhydrode, iV-substituted maleimide, diethylazodicarboxylate, or dimethy- lacetylene dicarboxylate (0.5 to 5 moles, preferably 0.8 to 2 moles) in the pres- ence of a solvnt while agitating at 0 to 150 °C, preferably at 20 to 120 ⁰ C, for 1 to 48 hours, preferably for 2 to 24 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1 ,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably toluene, may serve as the solvent. After completion of the reaction, the reaction mixture is washed, if necessary, with water, followed by removal of the solvent for instance

by evaporation to dryness. Heterocyclic Diels-Alder adduct of betulin is obtained as crude product that may be purified if necessary by crystallization, chromatography, or extraction, preferably by crystallization.

Method XIV

Substances having structures of the types IP described above may be produced by adding isocyanate (0.5 to 5 moles, preferably 0.8 to 1.5 moles) to ethylhydrazine (1 mol) in the presence of a solvent. The isocyanate R-N=C=O is selected from the group where R = H ₃ C ₁ -C ₆ linear or branched alkyl or alkenyl group or aro- matic group ZZ of the formula

where R5, R6 and/or R7 may represent H, C ₁ -C ₆ linear or branched alkyl or alkenyl group or C ₁ -C ₆ linear or branched alkyl or alkenyl ether, R5-R6 forms a cyclic C ₂ -C ₆ -alkyl or alkenyl group, halogen (fiuoro, chloro, bromo, iodo), nitro, carboxy, carboxyl, acetyl, R5-R6 forms a cyclic methylene dioxide group, sulfate, cyano, hydroxy, or trifluoromethyl. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably toluene, may serve as the solvent. The reaction mixture is agitated at 0 to 60 ⁰ C, preferably at 0 to 40 ⁰ C, for 0.5 to 12 hours, preferably for 1 to 5 hours, and 40 to 120 ⁰ C, preferably at 60 to 100 ⁰ C, for 0.5 to 12 hours, preferably for 1 to 5 hours. After completion of the reaction, the crude product formed is filtered and dried. The crude product, 4-substituted 1-carbethoxy semicarbazide may be purified by crystallization, chromatography, or extraction, preferably by extraction, if necessary.

Said 4-substituted 1-carbethoxy semicarbazide (1 mol) may be cyclized to give 4- substituted urazole by heating in an aqueous NaOH or KOH solution, preferably in aqueous KOH solution (1 to 10 M, preferably 2 to 6 M) at 40 to 100 °C, pref-

erably 50 to 80 °C, for 0.5 to 6 hours, preferably 1 to 3 hours. The reaction mixture is filtered, followed by precipitation of the crude product with concentrated HCl solution, filtered and dried for instance in an oven or desiccator. The crude material, 4-substituted urazole, may be purified by crystallization, chromatogra- phy, or extraction, preferably by crystallization, if necessary.

Said 4-substituted urazole (1 mol) is oxidized using iodobenzene diacetate (0.5 to 6 moles, preferably 0.8 to 1.5 moles) in the presence of a solvent while agitating at 0 to 80 °C, prferably at 20 to 40 ⁰ C for 0.1 to 4 hours, preferably 0.2 to 1 hours. NMP, DMF, DMSO, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxy ethane, acetone, ethyl acetate, hydrocarbons and/or chlorinated hydrocarbons, or mixtures thereof, preferably tetrahydrofuran or dichloromethane, may serve as the solvent. A mixture of 3/?,28-diacetoxylupa-12,18-diene and 3/?,28-diacetoxylupa- 18,21-diene produced according to the method XIII (0.2 to 2 moles, preferably 0.8 to 1.2 moles) is added to the reaction mixture, followed by agitating said reaction mixture at 0 to 60 ⁰ C, preferably at 0 to 40 ⁰ C, for 1 to 48 hours, preferably for 2 - to 24 hours, and then, the solvent is removed e.g. by evaporation to dryness. The crude product, a Diels-Alder adduct of the 4-substituted urazole, may be purified by crystallization, chromatography, or extraction, preferably by crystalli- zation.

The invention is now illustrated by the following examples without wishing to limit the scope thereof.

EXAMPLES

Example 1

Preparation of the 28-C ₁₈ alkylene succinic ester of betulin

Imidazole (38.8 mmol) and C ₁₈ alkylene succinic anhydride (ASA) 4 (11.6 mmol) were agitated in NMP (25 ml). Betulin 1 (9.7 mmol) was added, followed by further agitation at room temperature for 3 days. The organic phase was poured into water, decanted, dissolved in dichloromethane, and washed. The solvent was evaporated, thus yielding 28-C ₁₈ alkylene succinic ester of betulin 5 (yield: 73 %).

Example 2

Preparation of the 3,28-C ₁₈ alkylene succinic diester of betulin

Imidazole (54.2 mmol) and C ₁₈ alkylene succinic anhydride (ASA) 4 (32.5 mmol) were agitated in NMP (30 ml). Betulin 7 (13.5 mmol) was added, followed by further agitation of the mixture at room temperature for 3 days. The organic phase was poured into water, decanted, dissolved in dichloromethane, and washed. The solvent was evaporated, thus yielding 3,28-Cig alkylene succinic diester of betulin 6 (yield: 40 %).

Example 3

Preparation of the 28-carboxymethoxy mentholester of betulin

Betulin 1 (11.7 mmol) and menthoxyacetic acid 7 (11.7 mmol) were weighed in a flask, followed by the addition of toluene (120 ml). The mixture was heated to 120 ⁰ C, and added with isopropyl titanate (1.4 mmol). The reaction mixture was refluxed for 3 h untill water was separated by the water separation tube. The mixture was cooled to room temperature and the precipitate formed was filtered. The organic phase was washed and the solvent was evaporated, yielding 28- carboxymethoxy mentholester of betulin 8 (yield: 60 %).

Example 4

Preparation of the 28-carboxymethoxy carvacrolester of betulin

NaOH beads (66.6 mmol), dissolved in water, were added to a mixture of carvac- rol 9 (33.3 mmol), chloroacetic acid 10 (33.3 mmol) and water (50 ml). The mixture was refluxed at 120 °C for 3 h. The mixture was cooled to room temperature and acidified with hydrochloric acid. The crude product was extracted with di-

ethyl ether and washed with water. The solvent was evaporated, thus giving car- vacrol oxyacetic acid 11 (yield: 83 %). The crude product was purified by dissolving in diethyl ether, followed by extraction with water and NaHCO ₃ solution. Aqueous phases were pooled, acidified with hydrochloric acid and extracted with diethyl ether. The ether phase was dried, followed by evaporation of the solvent to dryness, thus giving carvacrol acetic acid 11 (yield: 45 %). Betulin 1 (7.2 mmol) and carvacrol oxyacetic acid 11 (7.2 mmol) were weighed into a flask, and toluene (80 ml) was added. The bath was heated to 160 ⁰ C, and then isopropyl titanate (1.4 mmol) was added. The reaction mixture was refluxed for 6 h untill all water was separated by the water separation tube. The mixture was cooled to room temperature and the precipitate formed was filtered. The organic phase was washed with NaHCO ₃ solution and the solvent was evaporated. The crude product was recrystallized from boiling solution of cyclohexane and toluene. The solvent was evaporated to dryness, thus isolating 28-carboxymethoxy carvacrolester of betulin 12 (yield: 55 %) as the reaction product.

Example 5

Preparation of the 28-chmamon alcohol acetic acid ester of betulin

A mixture of sodium hydride (8.2 mmol) and tetrahydrofuran was added with cinnamon alcohon 13 (7.5 mmol), and agitation was continued for 1 h. Methyl- chloroacetate (7.5 mmol) was added to the reaction flask, and agitation was continued for 24 hours. The reaction mixture was diluted with diethyl ether, and then

the organic phase was washed with water and dried. The solvent was evaporated to dryness, and the precipitate was dissolved in a solution of methanol and tetra- hydrofuran. Sodium hydroxide solution (10.9 mmol) was added, and the reaction mixture was refluxed for 4 hours. The solvent was evaporated. Water was added to the flask, acidified with hydrochloric acid, and extracted with diethyl ether. The organic phase was washed with water, and the solvent was evaporated, thus giving cinnamic acid 15 (yield: 23 %). Betulin 1 (0.9 mmol) and cinnamic acid 15 (0.9 mmol) were weighed into a flask, and toluene (40 ml) was added as the solvent. The bath was heated to 160 ⁰ C, and then isopropyl titanate (0.2 mmol) was added to the reaction mixture. The reaction mixture was refluxed for 4.5 h untill all water was separated by the water separation tube. The mixture was cooled to room temperature and the precipitate formed was filtered. The organic phase was washed with NaHCO ₃ solution and the solvent was evaporated. The crude product was recrystallized from boiling solution of cyclohexane and toluene. After the mixture was cooled, the crystallized precipitate was filtered. The solvent was evaporated to dryness, thus giving 28-cinnamon alcohol acetic acid ester of betulin 16 (yield: 14 %) as the reaction product.

Example 6

Preparation of 28-eugenolester of betulonic acid

A mixture of betulonic acid chloride 17 (1.4 mmol) (prepared as described in example 12), eugenol 18 (1.1 mmol), DMAP (1.1 mmol), and pyridine was heated for 48 hours at 40 ⁰ C. After completion of the reaction, the reaction mixture was diluted with toluene, washed with diluted hydrochloric acid solution, and water and then dried over sodium sulfate. The solvent was evaporated, thus giving 28- eugenol ester of betulonic acid 19 (yield: 81 %).

Example 7

Preparation of 28-carboxymethoxythymoI ester of betulin

l

23

NaOH beads (66.6 mmol), dissolved in water, were added to a mixture of thymol 20 (33.3 mmol), chloroacetic acid 21 (33.3 mmol) and water. The mixture was refluxed at 120 ⁰ C for 3 h. The mixture was cooled to room temperature, acidified, extracted with diethyl ether and washed. The solvent was evaporated thus giving precipitated thymolacetic acid 22 with a yield of 29 %. Betulin 1 (7.2 mmol), thymolacetic acid 22 (7.2 mmol), and toluene (80 ml) were heated to 160 ⁰ C, followed by the addition of isopropyl titanate (1.4 mmol). The reaction mixture was refluxed for 4.5 h untill all water was separated by the water separation tube. The mixture was cooled to room temperature and the precipitate formed was filtered. The organic phase was washed and the solvent was evaporated. The crude product was recrystallized from boiling solution of cyclohexane and toluene (3.5:1), thus giving 28-carboxymethoxythymol ester of betulin 23 (yield: 61 %) as the reaction product.

Example 8

Preparation of 28-chrysanthemate of betulin

Ethyl chrysanthemate 24 (23.3 mmol) was mixed to a THF/MeOH solution (1 :2) under an inert atmosphere. 2 M NaOH solution (93 ml) was slowly added to the mixture and the reaction mixture was heated at 80 °C for 4 hours until no starting material was detected by TLC (hexane: ethyl acetate 6:1, 5 % by volume of acetic acid). The solvent was evaporated, the crude product was dissolved in water (400 ml) and extracted with diethyl ether. The aqueous phase was acidified with hydrochloric acid and extrcted with diethyl ether. The ether phase was washed and the solvent was evaporated in vacuum, giving chrysanthemic acid 25 (yield: 90 %).

Chrysanthemic acid 25 (5.9 mmol) in anhydrous dichloromethane (30 ml) was added with oxalyl chloride (11.8 mmol) at room temperature under inert atmosphere. After six hours, the solvent was evaporated, and then the evaporation residue was taken up in dry dichloromethane, which was again evaporated. The procedure was repeated three times, thus giving chrysanthemic acid chloride 26 (yield: 81 %).

Betulin 1 (0.9 mmol), chrysanthemic acid chloride 26 (1.1 mmol) and DMAP (0.9 mmol) were agitated in pyridine at 40 ⁰ C under inert atmosphere for 48 hours. EtOAc (100 ml) was added, organic phase was washed with water, the solvent was evaporated, and the residue was recrystallized in cyclohexane. 28- chrysanthemate of betulin 27 were obtained with a yield of 63 %.

Example 9

Preparation of 28-cinnamic acid ester of betulin

Cinnamic acid 28 (18.06 mmol) and thionyl chloride (180.6 mmol) were mixed under inert argon atmosphere at 40 ⁰ C for 24 hours. Solvent was evaporated under vacuum, followed by dissolving the evaporation residue twice in dichloromethane and evaporation, thus giving cinnamic acid chloride 29 (yield: 99 %).

Betulin 1 (5.4 mmol) and cinnamic acid chloride 29 (5.6 mmol) were agitated in dry pyridine (80 ml) in the presence of DMAP (5.6 mmol) under inert argon atmosphere at 40 ⁰ C for 24 hours. Toluene (100 ml) was added, and the organic phase was washed. Solvent was evaporated, followed by purification of the crude product by recrystallization in a cyclohexane/toluene solvent. 28-cinnamic acid ester of betulin 30 was obtained with a yield of 67 %.

Example 10

Preparation of fatty acid esters of betulin

Betulin 1 (5 mmol) and' a fatty acid (5 mmol) were weighed in a flask equipped with a water separation tube. Toluene and a catalytic amount of isopropyl titanate

orp-toluenesulphonic acic were added, followed by refluxing the reaction mixture in an oil bath for about 5 hours. The reaction mixture was allowed to cool to room temperature, the organic layer was washed with sodium hydrogen carbonate solution, separated, dried over sodium sulfate, and then the solvent was evaporated to dryness. The crude product obtained, betulin monoester, was purified by chromatography, if necessary. In case more than 2 equivalents of the fatty acid and 1 equivalent of betuline were used, also betulin diesters were obtained as the product as shown in table 1. Table 1 shows yields of the esterification reactions of betulin with fatty acids, and degrees of esterification.

Table 1

Example 11 Preparation of 28-amide derivatives of betulin

Betulinic acid 3 was prepared by oxidizing betulin 1 according to the document US 6,280,778. Betulinic acid 3 (5 mmol) and aminoacid methyl ester hydrochloride 31 (5 mmol) were weighed in a flask and dissolved in dichoromethane. The flask was purged with argon, dichloromethane (5 mmol) and DMAP (2.5 mmol) were added and mixing was continued for 20 hours. The reaction mixture was diluted with ethyl acetate, washed with water, dried over sodium sulfate, and the solvent was evaporated to dryness. The betulinic acid amide 32 crude product may be purified by chromatography, if necessary. Reaction conditions and crude yields of the products are shown in Table 2.

Table 2

Example 12

Preparation of 28-aspartateamide dimethyl ester of betulonic acid

35

Betulonic acid 2 (8.8 mmol) was dissolved in dichloromethane under inert atmosphere, followed by the addition of oxalyl chloride (18.6 mmol). The reaction mixture was agitated at room temperature for 20 hours. After completion of the reaction, the solvent was evaporated to dryness, the residue was redissolved in dichloromethane, which was once more evaporated to dryness. The crude product obtained was washed with diethyl ether. The yield was 7.5 mmol (85 %) of betulonic acid chloride 33. Betulonic acid chloride 33 (4.2 mmol) and L-aspartic acid dimethyl ester hydrochloride 34 (5.5 mmol) were dissolved in dichloromethane, and triethyl amine (11 mmol) was added. The reaction mixture was agitated at room temperature for 20 hours. The reaction mixture was washed with diluted hydrochloric acid solution, water and dried over sodium sulfate. The solvent was evaporated to dryness, followed by purification of the crude product by chromatography, if necessary. Yield was 1.8 mmol (43 %) of the 28-aspartateamide dimethyl ester of betulonic acid 35.

Example 13

Preparation of 28-iV-acetylanthranilic acid ester of betulin

38

A mixture of iV-acetylanthranilic acid 36 (25.0 mmol) and oxalyl chloride (250 mmol) was mixed for 16 hours at 40 °C. Excessive oxalyl chloride was removed by evaporating the reaction mixture to dryness. The residue was twice dissolved in dichloromethane, which was evaporated to dryness. iV-acetylanthranilic acid

chloride 37 was thus obtained with a quantitative yield. A mixture of betulin 1 (11.29 mmol), DMAP (11.29 mmol), iV-acetylanthranilic acid chloride 37 and pyridine (80 ml) was agitated for 24 hours at 40 °C. After completion of the reaction, the reaction mixture was diluted with ethyl acetate and washed with diluted hydrochloric acid solution, and water and dried over sodium sulfate. The solvent was evaporated, followed by purification of the crude product by chromatography, thus giving 28-JV-acetylanthranilic acid ester of betulin 38 with a yield of 25 %.

Example 14 Preparation of 28-nicotinic acid ester of betulin (comparative)

A mixture of nicotinic acid 39 (25.0 mmol) and thionyl chloride (250 mmol) was mixed for 24 hours at 40 ⁰ C. Excessive thionyl chloride was removed by evaporating the reaction mixture to dryness. The residue was twice dissolved in di- chloromethane, which was evaporated to dryness. Nicotinic acid chloride 40 was thus obtained. A mixture of betulin 1 (2.26 mmol), DMAP (2.26 mmol), nicotinic acid chloride 40 (2.71 mmol) and pyridine (10 ml) was agitated for 24 hours at 40 ⁰ C. After completion of the reaction, the reaction mixture was diluted with ethyl acetate and washed with diluted hydrochloric acid solution, and water and dried over sodium sulfate. The solvent was evaporated, followed by purification of the crude product by recrystallization in cyclohexane, thus giving 28-nicotinic acid ester of betulin 41 with a yield of 88 %.

Example 15

Preparation 3,28-diacetoxy-19,20-ene-29-succinic anhydride of betulin

1 42 43 a) Acetic anhydride (19.2 ml, 203 mmol) was added to a mixture of betulin 1 (15.0 g, 33.88 mmol), DMAP (0.41 g, 3.39 mmol), pyridine (25 ml, 309 mmol), and dichloromethane (150 ml). The reaction mixture was agitated at room temperature for 17 hours. The organic phase was washed with 10 % hydrochloric acid solution (200 ml), saturated NaHCO ₃ solution (400 ml), water (100 ml), and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum, thus giving 3,28-diacetoxy betulin 42 with a yield of 97 %.

b) A mixture of 3,28-diacetoxy betulin 42 (4.57 g, 8.68 mmol) and hydrochinone (96 mg, 0.87 mmol) was heated at 200 °C, followed by the addition of succinic anhydride (2.50 g, 25.02 mmol) during 2 hours to the reaction flask. After completion of the reaction, as the crude product, 3,28-diacetoxy- 19,20-ene-29- succinic anhydride of betulin 43 was obtained with a yield of 100 % (5.41 g, 8,65 mmol).

Example 16

Perparation of 3-deoxy-2,3-dihydrobetulin (comparative)

1 44

A solution of diethylazo dicarboxylate (DEAE, 20.71 ml, 45.18 mmol) in dry THF (100 ml) was added dropwise unden a nitrogen atmosphere to a mixture of

betulin 1 (5.00 g, 11.29 mmol), triphenyl phosphine (PPh ₃ , 11.85 g, 45.18 πunol), and 3,3-dimethyl glutarimide (6.38 g, 45.18 mmol) in an ice bath. The reaction mixture was allowed to warm to room temperature, and agitating was continued for 24 hours. The precipitate formed was separated by filtering, followed by evaporating the solvent in vacuum. The crude product was purified by chromatography, thus giving 3-deoxy-2,3-dihydrobetulin 44 (1.47 g, 3.45 mmol, 31 %).

Example 17

Preparation of 3-0-Diels-Alder adduct of betulin

45 46 47 48

2,4-pentadiene acid 45 (196 mg, 2.0 mmol) and 4-phenyl-l,2,4-triazoIin-3,5-dion 46 (350 mg, 2.0 mmol) were dissolved in a mixture of hexane and toluene. The reaction mixture was agitated under inert atmosphere at room temperature for 3 days. After completion of the reaction, the solvent was evaporated, thus giving the Diels-Alder adduct 47 (493 mg, 1.80 mmol, 90 %).

Pyridinium-/?-toluenesulfonate (PPTS) (0.68 g, 2.71 mmol) and dihydropyran (DHP) (2.09 g, 24.9 mmol) were added to betulin 1 (10.0 g, 22.6 mmol) in di- chloromethane (330 ml) under inert atmosphere, and then the reaction mixture was agitated at room temperature for 5 days. After completion of the reaction, the organic phase was washed with saturated NaHCO ₃ solution (150 ml) and water (150 ml), followed by drying over Na ₂ SO ₄ . The solvent was evaporated in vacuum, and the crude product obtained was purified by chromatography, thus giving the 28-tetrahydropyran ether of betulin 48 (3.46 g, 6.55 mmol, 29 %).

28-tetrahydropyran ether of betulin 48 (116 mg, 0.22 mmol) and the Diels-Alder adduct 47 (60 mg, 0.22 mmol) were dissolved in a mixture of hexane and toluene. Diphenylphosphoryl azide (DPPA) and triethylamine (TEA) were added to the reaction mixture, which was refluxed for 24 hours. After completion of the reaction, the reaction mixture was diluted with ethyl acetate, the organic phase was washed with water, NaHCO ₃ solution, diluted hydrochloric acid solution and water, followed by drying over Na ₂ SO ₄ . The solvent was evaporated in vacuum, thus giving crude product (419 mg) that was purified by chromatography, thus giving the 3-O-Diels-Alder adduct of the 28-tetrahydropyran ether of betulin 49 (yield: 50 %).

A mixture of the 3-O-Diels-Alder adduct of the 28-tetrahydropyran ether of betulin 49 (50 mg, 0.063 mmol), pyridinium-p-toluene sulfonate (PPTS) (3 mg, 0.013 mmol), and methanol (10 ml) was agitated at room temperature under an inert atmosphere for two weeks. After completion of the reaction, NaHCO ₃ solution (10 ml) was added to the reaction mixture. The aqueous phase was extracted with ethyl acetate (40 ml), which was washed with water (80 ml), dried over Na ₂ SO ₄ , followed by evaporation of the solvent in vacuum. The crude product was purified by chromatography, 3-O-Diels-Alder adduct of betulin 50 was thus obtained (yield: 50 %).

Example 18

Preparation of the Diels-AIder-adduct of 4-methylurazole with betulin

54 55

toluene

To a mixture of betulin 1 (15.0 g, 33.88 mmol), λζiV-dimethylamino pyridine (DMAP, 0.41 g, 3.39 mmol), pyridine (25 ml, 309 mmol), and dichloromethane (150 ml), acetic anhydride (19.2 ml, 203 mmol) was added. The reaction mixture was mixed at room temperature for 17 hours. Organic phase was washed with 10 % hydrochloric acid solution (200 ml), saturated NaHCO ₃ solution (400 ml), and water (100 ml) and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum, thus giving betulin 3,28-diacetate 51 (yield: 97 %).

To a mixture of hydrobromic acid (HBr) (47 %, 250 g), acetic anhydride (100 g), and acetic acid (300 g), betulin 3,28-diacetate 51 (17.41 g, 33.05 mmol) dissolved in toluene (200 ml) was added. The reaction mixture was allowed to stand at room

temperature for 3 weeks. The reaction mixture was diluted with water (400 ml). The aqueous phase was separated and extracted with toluene (400 ml). Pooled organic phases were washed with water (30 ml), saturated NaHCO ₃ solution (600 ml), dried over Na ₂ SO ₄ , and the solvent was evaporated in vacuum. The crude product was purified by chromatography giving 3/?,28-diacetoxylup-18-ene 52 (7.36 g, 13.97 mmol, 42 %).

To a mixture of 3/?,28-diacetoxylup-18-ene 52 (4.91 g, 9.33 mmol) and Na ₂ CO ₃ (4.94 g, 46.65 mmol) in chloroform (120 ml), m-chloroperbenzoic acid (mCPBA, 3.69 g, 14.92 mmol) was added, and the mixture was agitated at RT for 2 hours. The organic phase was washed with water (150 ml), saturated NaHSO ₃ solution (150 ml), saturated NaHCO ₃ solution (150 ml), dried over Na ₂ SO ₄ , and the solvent was evaporated in vacuum. The crude product was recrystallized in ethanol giving 3/?,28-diacetoxylup-18£19£-epoxyluρane 53 (3.31 g, 6.09 mmol, 65 %).

3/?,28-diacetoxylup-18£19£-epoxylupane 53 (2.00 g, 3.68 mmol) and p- toluenesulfonic acid (0.42 g, 2.21 mmol) were dissolved in toluene (80 ml), and then acetic anhydride (0.56 ml, 5.90 mmol) was added. The reaction mixture was refluxed for four hours. Organic phase was washed with saturated NaHCO ₃ solu- tion (150 ml), and water (100 ml), dried over Na ₂ SO ₄ , and the solvent was evaporated in vacuum. The crude product was purified by chromatography and crystallized in ethanol, thus giving a mixture of 3/?,28-diacetoxylupa-12,18-diene 54 and 3/?,28-diacetoxyluρa-18,21-diene 55 (4:1) (1.31 g, 2.50 mmol, 68 %).

3/?,28-diacetoxylupa-12,18-diene 54, 3/?,28-diacetoxylupa-18,21-diene 55 (total amount of 100 mg, 0.19 mmol), and 4-methyl-l,2,4-triazolin-3,5-dion (32 mg, 0.29 mmol) were dissolved in toluene (5 ml), and then the reaction mixture was agitated at room temperature for 24 hours. The solvent was evaporated in vacuum and the crude product was purified by chromatography, thus giving Diels-Alder- adduct of 4-methylurazole with betulin 56 (60 mg, 0.09 mmol, 49 %).

Example 19

Preparation of Diels- Alder adduct of /j-acetyl-4-phenylurazole with betulin

61

To ethylhydrazin 57 (2.64 mmol) in toluene (5 ml), 4-acetylphenyl isocyanate 58 (2.64 mmol) dissolved in 5 ml of toluene was added dropwise under an inert atmosphere. Agitation was continued for 2 hours at room temperature, and at 80 ⁰ C for 2 hours. Filtering of the precipitate formed and drying thereof in the oven gave ^-acetyl-4-phenyl-l-carbethoxy semicarbazide 59 (yield: 90 %).

This p-acetyl-4-phenyl-l-carbethoxy semicarbazide 59 (1.13 mmol) was heated at 70 °C in an aqueous 4M KOH solution (2.26 mmol) for 1.5 hours. The precipitate was filtered off, followed by acidification of the cooled filtrate with concentrated HCL solution. The precipitate formed was filtered and dried in a desiccator, thus giving p-acetyl-4-phenylurazole 60 (yield: 65 %).

A mixture of /?-acetyl-4-phenylurazole 60 (50 mg, 0.229 mmol), and iodobenzene diacetate ((PhI(OAc) ₂ , 74 mg, 0.229 mmol) was agitated under an inert atmos-

phere in an anhydrous THFiCH ₂ Cl ₂ mixture (4 ml, 1 :1) for 15 minutes yielding a red colour. 3/?,28-diacetoxylupa-12 ₅ 18-diene 54 (100 mg, 0.191 mmol) was dissolved in a THF:CH ₂ Cl ₂ mixture (4 ml, 1:1) and added to the reaction flask, and agitation was continued for 24 hours at room temperature. The solvent was evaporated in vacuum. Purification of the crude product by chromatography gave a Di- els-Alder adduct of betulin with p-acetyl-4-phenylurazole 61 (yield: 30 %). Table 3 below shows the percent yields of the Diels-Alder adducts of betulin with ura- zole for different groups R:

O^ ?N _V O

F N-N

Table 3 H H

R Yield (%) R Yield (%)

Example 20

Preparation of betulin 3-acetoxy-28-l',2',3'-triazoles and betulin 3-acetoxy-

28-tetrazoles

62

63

To betulin 1 (10.0 g, 22.6 mmol) in dichloromethane (330 ml), pyridinium-p- toluenesulfonate (PPTS) (0.68 g, 2.71 mmol), and dihydropyrane (DHP) (2.09 g, 24.9 mmol) were added under inert atmosphere, followed by agitation of the reaction mixture at room temperature for 5 days. After completion of the reaction, the organic phase was washed with saturated NaHCO ₃ solution (150 ml) and water

(150 ml), then dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum, and then the crude product was purified by chromatography, thus giving betulin 28- tetrahydropyrane ether 48 (3.46 g, 6.55 mmol, 29 %).

To a mixture of betulin 28-tetrahydropyrane ether 48 (5.00 g, 9.49 mmol), N,N- dimethylamino pyridine (DMAP, 0.12 g, 0.95 mmol), pyridine (10 ml, 124 mmol), and dichloromethane (50 ml), acetic anhydride (5.4 ml, 57 mmol) was added. The reaction mixture was agitated at room temperature for 20 hours. The organic phase was washed with 10 % hydrochloric acid aolution (300 ml), satu- rated NaHCO ₃ solution (400 ml), water (100 ml), and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum, thus giving betulin 3-acetoxy-28- tetrahydropyrane ether 62 (yield: 95 %).

A mixture of betulin 3-acetoxy-28-tetrahydropyrane ether 62 (3.00 g, 5.27 mmol), pyridinium-p-toluenesulfonate (PPTS) (226 mg, 1.06 mmol), and methanol (100 ml) was agitated at room temperature under an inert atmosphere for 2 weeks. After completion of the reaction, NaHCO ₃ solution (100 ml) was added to the reaction mixture. The aqueous phase was extracted with ethyl acetate (400 ml), followed by washing with water (800 ml), dried over Na ₂ SO ₄ , the solvent was evaporated in vacuum, thus giving betulin 3-acetate 63 (yield: 94 %).

To a mixture of betulin 3-acetate 63 (100 mg, 0.21 mmol) and diethyl ether (10 ml), pyridine (163 mg, 2.1 mmol) and phosphorus tribromide (PBr ₃ ) (280 mg, 1.0 mmol) were added at -5 ⁰ C under an inert atmosphere. The reaction mixture was allowed to warm to room temperature while continuing mixing for 24 hours. After completion of the reaction, the organic phase was washed with water (100 ml), NaHCO ₃ solution (80 ml) and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum, thus giving betulin 3-acetoxy-28-bromide 64 (yield: 63 %).

A mixture of betulin 3-acetoxy-28-bromide 64 (200 mg,0.36 mmol), NaN ₃ (230 mg, 3.6 mmol), and DMF (20 ml) was heated at 100 °C under an inert atmosphere

for 24 hours. After completion of the reaction, the solvent was evaporated in vacuum and the residue was taken up in ehtyl acetate (100 ml). The organic phase was washed with water (225 ml), dried over Na ₂ SO ₄ and the solvent was evaporated in vacuum, thus giving 149 mg of the crude product comprising 20 % of betulin 3-acetoxy-28-azide 65.

Using known methods, betulin 3-acetoxy-28-azide 65 may be reacted with arylni- triles, giving betulin 3-acetoxy-28-tetrazoles 66, or with a functional alkyne in the presence of CuSO ₄ -5H ₂ O and sodium ascorbate in an aqueous butanol solution, giving betulin 3-acetoxy-28-l',2',3'-triazoles 67.

Example 21

Preparation of betulin 3,28-dibetaine ester

Betulin 1 (7.0 g, 16 mmol) and betaine 68 (3.8 g, 32 mmol) were dissolved in toluene (150 ml) while heating. Thereafter, isopropyl titanate Ti(OCHMe ₂ ) ₄ catalyst (0.85 g, 3 mmol) was added, and the mixture was refluxed for 3 hours. The solid final product was separated by filtration. Tetrahydrofurane was added to remove by-products, and filtering was repeated. Yield of the final product 69 (betulin 3,28-dibetaine ester) was 2.7 g (4.1 mmol, 26 %).

Example 22

Preparation of 28-acetate of betulonic alcohol

a) To a mixture of betulin 1 (8.00 g, 18.1 mmol) and 4-dimethylamino pyridine (DMAP) (0.8 g, 6.55 mmol) in dichloromethane (72 ml), pyridine (72 m) and acetic anhydride (1.8 ml, 19,1 mmol) were added, and the reaction mixture was agitated at room temperature for 22 hours. The organic layer was washed with 10 % hydrochloric acid solution, water, saturated NaHCO ₃ solution, and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum, followed by purification of the crude product obtained by chromatography, thus giving 28-acetoxybetulin 70 (3.80 g, 45 %).

b) A mixture of betulin 28-acetate (590 mg, 1.23 mmol) and pyridinium chloro- chromate (PCC) (1.32 g, 3.14 mmol) in dichloromethane (60 ml) was agitated at room temperature for 24 hours. The reaction mixture was diluted with diethyl ether (30 ml), agitated for 10 minutes, and the precipitate was filtered off. The filtrate was evaporated in vacuum and the crude product was purified by chromatography, thus giving 28-acetate of betulonic alcohol 71 (330 mg, 57 %).

Example 23

Preparation of betulonic and betulinic acids (comparative)

a) To a solution of betulin 1 (50 g, 113 mmol) in acetone (1500 ml), a Jones reagent was added during 1 hour in an ice bath. The reaction mixture was allowed to warm to room temperature, and agitation was continued for 21 hours. Methanol (700 ml) and water (1000 ml) were added to the reaction mixture. The precipitate was filtered, dried in vacuum, taken up in diethyl ether (600 ml) and washed with water, 7.5 % hydrochloric acid, water, saturated NaHCO ₃ solution, and again with water. Half of the diethyl ether was evaporated in vacuum and the residue was treated with 10 % NaOH solution. The precipitate was filtered, dried in vacuum, and dissolved in boiling methanol, followed by the addition of acetic acid (10 ml) thereto. The product was precipitated with water, filtered and dried in vacuum, thus giving betulonic acid 2 (22.3 g, 44 %).

b) To betulonic acid 2 (10 g, 22 mmol) in 2-propanol (400 ml), NaBH ₄ (1.76 g, 44.2 mmol) was added, and the reaction mixture was agitated at room temperature for 2 hours. 10 % hydrochloric acid solution (600 ml) was added, the precipitate was filtered, washed with water and dried in vacuum. The crude product obtained was cyrstallized in ethanol, thus giving betulinic acid 3 (8.25 g, 18 mmol).

Example 24 Preparation of betulonic aldehyde (comparative)

1 72

A mixture of betulin 1 (3.0 g, 6,8 mmol), pyridinium chlorochromate (PCC) (8.8 g, 41 mmol) and dichloromethane was agitated at room temperature for 1 hour. The reaction mixture was dissolved with diethyl ether and filtered through alu- mina. The filtrate was washed with water, 5 % hydrochloric acid, again with water and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum and the crude

product was crystallized in a mixture of hexane and ethyl acetate, thus giving betulonic aldehyde 72 (2.4 g, 82 %).

Example 25

Preparation of 28-methyl ester of betulinic acid

3 ⁷³

To a mixture of betulinic acid 3 (100 mg, 0.22 mmol), methanol (1 ml) and toluene (1.5 ml), a 2M solution of trimethylsilyl diazomethane in diethyl ether (0.17 ml, 0.33 ml) was added and the reaction mixture was agitated at room temperature for 40 minutes. The solvent was evaporated in vacuum, thus giving 28-methyl ester of betulinic acid 73 (68 mg, 66 %).

Example 26

Preparation of betulin aldehyde, betulin 28-oxime and betulin 3,28-dioxime

74 ⁷² a) A mixture of betulin 1 (8.0 g, 18 mmol) and pyridinium chlorochromate (PCC) (7.0 g, 33 mmol) in dichloromethane (800 ml) was agitated at RT for 40 min. The reaction mixture was diluted with diethyl ether (200 ml) and filtered through alu-

minium oxide. The solvent was evaporated in vacuum and the crude product was purified by chromatography, thus giving betulin aldehyde 74 (0.36 g, 18 %).

b) To a mixture of betulonic aldehyde 72, betulinic aldehyde 74, pyridine (40 ml) and ethanol (120 ml), hydroxylamine hydrochloride (10 g, 144 mmol) was added, followed by refluxing the reaction mixture for 18 hours. The solvent was evaporated in vacuum and the mixture of betulin 28-oxime 75 and betulin 3,28-dioxime 76 obtained was purified by chromatography, thus giving betulin 28-oxime 75 (0.97 g, 2.1 mmol) and betulin 3,28-dioxime 76 (0.32 g, 0.7 mmol).

Example 27

Preparation of betulonic alcohol

A mixture of betulonic 28-acetate 70 (15 mg, 0.032 mmol), methanol (0.3 ml), tetrahydrofurane (0.45 ml) and 1 M NaOH solution (0.16 ml) was agitated at RT for 20 hours. Water (4 ml) was added and the reaction mixture was made acidic with diluted HCl. The aqueous phase was extracted with ethyl acetate, which was dried over Na ₂ SO ₄ and evaporated in vacuum, thus giving 77 (7.0, 50 %).

Example 28

Preparation of betulin 3~acetoxyoxime-28-nitriIe

76

A mixture of betulin 3,28 dioxime 76 (100 mg, 0.2 mmol) and acetic anhydride (2.5 ml) was agitated at 120 °C for 2 hours. The reaction mixture was diluted with water and the precipitate was filtered. The precipitate was taken up in chloroform, washed with water, saturated NaHCO ₃ solution, water and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum and the crude product was purified by chromatography, giving betulin 3-acetoxyoxime-28-nitrile 78 (37 mg, 34 %).

Example 29

Preparation of betulin 28-acetic acid methyl ester

1 79 80

A mixture of betulin 1 (1.0 g, 2.3 mmol) and potassium tert-butoxide (2.5 g, 23 mmol) in tetrahydrofurane (50 ml) was agitated at 75 °C, followed by the addition of methylbromoacetate 79 (2.1 ml, 23 mmol). The reaction mixture was agitated for 10 minutes, allowed to cool and then diluted with water. The precipitate was filtered and the crude product was purified by chromatography, thus giving betulin 28-acetic acid methyl ester 80 (0.2 g, 15 %).

Example 30

Preparation of 20,29-dihydrobetulin and 20,29-dihydrobetulonic acid

Jones oxidation acetone

81 82 a) To a mixture of betulin 1 (2.0 g, 4.5 mmol), tetrahydrofurane (40 ml) and methanol (80 ml), 5 % Pd/C (0.2 g) was added, followed by agitating the reaction mixture under hydrogen atmosphere for 22 hours. The reaction mixture was fil-

tered, and the filtrate was evaporated in vacuum, thus giving 20,29-dihydrobetulin 81 (2.0 g, 99 %).

b) To a mixture of 20,29-dihydrobetulin 81 (1.0 g, 2.3 mmol) and acetone (75 ml), Jones reagent was added. The reaction mixture was agitated for 20 hours. Methanol (20 ml) and water (40 ml) were added to the reaction mixture. The organic solvent was evaporated in vacuum and the aqueous phase was extracted with ethyl acetate, which was washed with water and dried over Na ₂ SO ₄ . The solvent was evaporated in vacuum and the crude product was purified by chromatography, thus giving 20,29-dihydrobetulonic acid 82 (320 mg, 31 %).

Example 31

Preparation of a Diels-Alder adduct of 4-methylurazoIe

A mixture of Diels-Alder adduct of 4-methylurazole 56 (50 mg, 0.07 mmol), methanol (0.5 ml), tetrahydrofurane (0.8 ml) and 1 M aqueous NaOH solution (0.3 ml) was agitated at room temperature for 20 hours. The product was precipitated with water, the precipitate was filtered and dried, thus giving the Diels-Alder adduct of 4-methylurazole 83 (40 mg, 91 %).

Example 32

Cytotoxicity tests of the betulin derived compounds

Caco-2 cells (cell line used as a model for human intestine) were introduced in a 96 well plate in an amount of 35 000 cells (for LDH method), 45 000 cells (for

WST-I method), or 25 000 cells (for ATP method) per well. After proliferation

for 24 hours, the cells were exposed to the compounds being tested for 24 hours by adding said compounds to the cultivation medium to give a concentration of 500 μM (as stock solutions in DMSO).

The influence of the compounds on the viability of the cells was measured by three different methods. Polymyxin B was used as the control. Lactate dehydrogenase (LDH) is an enzyme found in cells, and accordingly, increased amounts thereof outside cells result from cell membrane damage. The amount of LDH in the sample due to exposure was quantified by means of an enzymatic reaction using the INT (iodonitrotetrazolium) colour reagent wherein the coloured reaction product formed was determined photometrically at 490 nm. In the WST-I method, the metabolic activity of the cells after exposure was measured using the WST-I reagent. Metabolic activity of a cell results in the generation of a coloured product from the reagent, said product being then used to evaluate the viability of the cells by photometric measurements (absorbance at 440 nm). In the ATP method, the amount of ATP within cells decreasing rapidly due to cellular damage was measured. In the method, ATP was luminometrically quantified by means of the ATP dependent luciferase-luciferin reaction.

Appended figure 1 shows effects on the viability of Caco-2 cells (%) after exposure for 24 hour as measured by three methods for the determination of cellular viability (LDH, WSR-I and ATP methods). Compounds exceeding the limit value, i.e. 80 % viability, are considered to have no significant negative effect on the viability of cells is virto. The compounds of the Table 4 were used for testing.

Table 4

Example 33

Determination of the antiviral activity of betulin derived compounds

Antiviral properties of betulins were studied using a method measuring the replication of Semliki Forest virus wherein BHK cells growing in wells of a microliter plate are infected with the Semliki Forest virus, followed by determination of the luciferase enzyme introduced into the viral genome 14 hours after the start of the virus exposure. The test samples added at the same time with the virus are solu- tions in dimethyl sulfoxide diluted with test buffer (MEM + 0.2 % BSA) to a final concentration of the sample of 50 μM, the final dimethyl sulfoxide concentration being 1 %. Activities of samples inhibiting replication of SFV on another alphavi- rus, Sindbis virus (SIN) were determinated using uridine labeling assay where BHK cells are also infected with diluted viruses. ³ H-labeled uridine was added to cell cultivation in 13 hours after the start of the virus exposure, followed by washing of the cultivations in 1 hour, disrupting with 1 % SDS solution, and determining radioactivities bound to samples by trichloroacetic acid precipitation method. Binding of the radioactive label to the host cells is inhibited by the addition of

actinomycin D inhibiting RNA synthesis in mammal cells. The amount of the residual luciferase activity or the radioactivity in % indicative of the virus replication in comparison to the negative control used in the experiment (1 % dimethyl sulfoxide alone) are presented as the results. 3'-amino-3'-deoxyadenosine (25 μM) with activity against SFV and SIN viruses already known from previous tests was used as the positive control.

Table 5 shows results indicative of the antiviral activities of compounds derived from betulin, obtained from tests for inhibition of the Semliki Forest virus (SFV). In the table, Prim. Screen (% left) refers to the amount of replication of the viruses

_* left in case betulinderived compound is used at a concentration of 50 μM. IC ₅₀ is the concentration of the compound tested sufficient to inhibit 50 % of the virus replication.

Table 5