The term"polycosanols"is intended to indicate linear long- chain primary aliphatic alcohols having from 20 to 36 carbon atoms; of particular interest within the scope of the inven- tion are the compounds having from 26 to 30 carbon atoms.

Polycosanols are known as compounds having pharmacological activity, particularly in the treatment of hypercholesterol- aemia; their use as anti-inflammatory and antithrombotic agents is also known, as is their activity in improving sex- ual activity.

Typically, mixtures of polycosanols are obtained by extrac- tion processes from natural waxes, such as, for example, bees-wax, sugar cane wax and rice wax.

The processes of extraction with a solvent from natural sub- stances result in the obtainment of complex mixtures of poly- cosanols from which it is possible to obtain a single com- pound of interest only after expensive purification opera- tions.

For example, EP-A-0 619 802 describes a mixture of polyco- sanols which is obtained from sugar cane and which contains, as principal components, 1-octacosanol and 1-triacontanol to- gether with smaller amounts of 1-tetracosanol, 1- heptacosanol, 1-dotriacontanol and 1-tetratriacontanol.

Processes for the preparation of polycosanols by reduction of the corresponding n-alkanoic acids or polycosanoic acids ob- tained by synthesis are also known.

US Patent 4 294 770 describes a process for the synthesis of long-chain n-alkanoic acids, which can be used as intermedi- ates for the preparation of the corresponding polycosanols, by reaction of trihalomethane with normal-a-olefins having from 25 to 35 carbon atoms in the presence of a radical ini- tiator and by subsequent alkaline hydrolysis of the tri- haloalkane so obtained. A disadvantage associated with that process resides in the fact that normal-a-olefins having from 25 to 35 carbon atoms are not commercially available in the pure state and therefore the process does not permit the production of polycosanoic acids and corresponding polyco- sanols that are substantially pure, except at the cost of ex- pensive purification operations.

An object of the present invention is to provide an improved process which permits the production of polycosanoic acids, their esters and/or polycosanols, and also the production of corresponding unsaturated compounds with a limited number of synthesis steps starting from commercially available and in- expensive reagents.

Another object of the invention is to provide a process which permits the production of individual polycosanols and polyco- sanoic acids and corresponding mono-or poly-unsaturated com- pounds of high purity.

In view of those objects, the invention relates to a process as defined in the claims which follow.

The key step of the synthesis according to the invention is a <BR> <BR> Wittig olefination reaction (cf. Merck Index, 12a ed. , ONR-99 and bibliographical references mentioned therein) in which a phosphorus ylide RP (Ar) 3, wherein Ar is aryl (phenyl) and R is a saturated or unsaturated hydrocarbon chain, particularly a phosphorus ylide of a linear alkane, alkene, diene, triene or alkyne, is reacted with an n-alkanoic acid, formylated in the terminal position, or with its corresponding alkyl ester (preferably lower alkyl having from 1 to 4 carbon atoms) to give the addition product constituted by the acid or alkyl ester with intermediate ethylenic unsaturation, having the desired chain length.

Alternatively, it is possible to operate in accordance with the Peterson olefination reaction (Merck Index, 12th ed. , ONR-69) which uses, instead of the above-mentioned phosphorus ylide, the a-silylcarbanion of a linear alkane; however, the Peterson reaction is less preferred owing to the greater dif- ficulty of forming the a-silylcarbanions.

The process according to the invention can be used for the preparation of polycosanols and polycosanoic acids, their es- ters and corresponding mono-or poly-unsaturated compounds generally having from 20 to 36 carbon atoms and preferably having from 26 to 30 carbon atoms; the compounds of greatest interest being octacosanol and octacosanoic acid and their C27 homologues.

In general, for the preparation of the desired compounds of formula CH3- (CH2) p-X, wherein: p is an integer, preferably from 22 to 34, or more preferably from 24 to 28, and X is-CH20H, or-COORl wherein R1 denotes hydrogen or Cl-C4 lower alkyl, or of corresponding mono-or poly-unsaturated compounds hav- ing a hydrocarbon chain, it is possible to vary the chain length of both reagents.

For example, in the Wittig reaction-for the preparation of saturated or mono-unsaturated compounds-a phosphorus ylide of formula: CH3- (CH2) m-P (Ar) 3 is used in which: m is an integer from 8 to 22 carbon atoms, and Ar is aryl, preferably phenyl, which is reacted with a compound of formula O=CH- (CH2) n-COORl, wherein: n is an integer from 2 to 12 and preferably from 6 to 12, and Ri has the meaning defined above, and wherein: n + m + 1 is equal to p.

Similar considerations apply in relation to the Peterson re- action.

Analogously, for the preparation of poly-unsaturated com- pounds, a phosphorus ylide R3P (Ar) 3 is used wherein R3 is an unsaturated hydrocarbon chain, for example, including from 1 to 4 ethylenic and/or acetylenic unsaturations.

However, in the preferred embodiment, the saturated or un- saturated compounds and particularly the polycosanols and the polycosanoic acids having the desired chain length are pre- pared using 10-oxo-decanoic acid or its alkyl ester, varying the hydrocarbon chain length of the phosphorus ylide.

In this preferred embodiment, the starting reagent used is 10-undecenoic acid which is an inexpensive commercially available product in a highly purified form (purity 99%).

In this embodiment, the 10-undecenoic acid is preferably pro- tected by an esterification reaction and the ester of the un- decylenic acid so obtained is then subjected to oxidation of the terminal unsaturation to aldehyde.

It is, however, possible to proceed directly with oxidation without previous esterification.

For example, the operation is effected in accordance with the following operative stages: 1. Esterification of undecylenic acid with alcohol (methanol) Method a) The reaction is catalysed with acid (preferably p-toluene- sulphonic acid) and heating under reflux is effected in a solvent (preferably toluene) in the presence of methanol; the water is removed using a Dean Stark or Markusson distilling apparatus.

Method b) The reaction is carried out with magnetic agitation at ambi- ent temperature in methanol in the presence of acetyl chlo- ride as the catalyst, with reaction times of the order of 7 hours.

1.1 Oxidative clearage of the terminal alkene to aldehyde Method a) The oxidation is effected with catalytic amounts of osmium tetroxide (for example, 0.01 molar equivalents, 0.2 M solu- tion in toluene) and sodium periodate in an ether/water solu- tion with agitation at ambient temperature with reaction times of approximately 3 hours.

Method b) With catalytic osmium tetroxide (for example, 0.005 molar equivalents, 0.2 M solution in toluene) and sodium periodate in an acetone/water solution with magnetic agitation at ambi- ent temperature and in the presence of N-methylmorpholine N- oxide as the co-oxidant, with reaction times of the order of approximately 90 minutes.

Method c) With potassium permanganate, previously mixed with acid alu- mina, preferably in the ratio 1: 2.5 and an equal amount by weight of water with magnetic agitation in dichloromethane; approximately 10% of the corresponding carboxylic acid is ob- tained together with the aldehyde.

Method d) With potassium permanganate and sodium periodate in water with vigorous agitation at ambient temperature.

Bearing in mind the cost of osmium tetroxide (OS04) or the equivalent potassium osmate (K2OsO4. 2H2O), method b) mentioned above, which permits the use of small catalytic amounts of osmium in the presence of a cooxidant, such as N- methylmorpholine N-oxide, is clearly preferred.

The following scheme summarises the reaction conditions indi- cated above, according to the preferred embodiment which uses 10-undecylenic acid. Methanol 10 eq ... PTSA u I OH PTSA N. OCH3 Toluene reflux Dean Stark 93% Cat. OsO4/NMO OCH3) p OCH3 Na104 0 f H20/acetone ggy 86/o NMO: N-methylmorpholine N-oxide The n-alkane phosphorus ylide used in the Wittig reaction is prepared by reacting the corresponding halogen derivative (where halogen is preferably bromine or chlorine) with triph- enylphosphine, preferably in a high-boiling solvent (toluene) while heating under reflux; at the end of the reaction, the solution is concentrated and the phosphonium salt is precipi- tated, preferably with ether.

For the preparation of octacosanol and octacosanoic acid, 1- bromooctadecane is a reagent which is widely commercially available, with a high degree of purity (at least 96%), and inexpensive.

The following scheme illustrates the preparation of the phos- phonium salt of 1-bromooctadecane.

2. Preparation of the phosphonium salt of 1-bromooctadecane Heating is effected under reflux with triphenylphosphine in toluene for 24 hours; the solution is concentrated and the phosphonium salt is precipitated with ether. Triphenylphosphine Bu duo C1gHg7Br Toluene under reflux 80% ! ! J Br I 15 3. Wittig reaction The Wittig reaction can be carried out using n-alkanoic acid, formylated in the terminal position, or the corresponding al- kyl ester, preferably methyl ester, operating in accordance with the following reaction conditions.

A) Reaction carried out on the alkyl ester: the phosphonium salt (preferably bromide) of n-alkane is converted into phos- phorus ylide by reaction with a strong base (preferably butyl lithium) in an ethereal solvent, preferably tetrahydrofuran; the conversion is characterized by the colour change from yellow to intense orange. The aldehyde solution, preferably in tetrahydrofuran, prepared in point 1 above, is then added dropwise to give the cis-trans mixture of C1-C4 alkyl poly- cosenoate.

B) On the acid: 1. The phosphorus ylide is prepared by reacting the n-alkane phosphonium salt (bromide) with a strong base; the preferred conditions provide for the use of at least two molar equiva- lents of butyl lithium in THF in order to salify the carbox- ylic function present in the formyl acid, the solution of which (preferably in tetrahydrofuran) is subsequently added dropwise to give the cis-trans mixture of the desired poly- cosenoic acid.

2. First of all the sodium salt of n-alkanoic acid, which is formylated in the terminal position using sodium hydride in tetrahydrofuran, is prepared; the solvent is evaporated and then the procedure is as in point A indicated above.

The Wittig reaction, relating to the preparation of cis-trans methyl octacosenoate using methyl 10-oxo-decanoate, is illus- trated in the following scheme. w p@4 BuLi, THF OCH3 + O oc3 ° r 90% (cis, trans) 0 C2gHs602 (cis, transJ o The (C-10) mono-unsaturated C1-C4 alkyl esters (alcoholic com- ponent) having from 20 to 36 carbon atoms (acid component) constitute novel synthetic intermediates, forming the sub- ject-matter of the present invention.

4. The above-mentioned mono-unsaturated alkyl ester or the corresponding acid is then subjected to catalytic hydrogena- tion of the double bond, for example, operating with palla- dium on carbon, to obtain the corresponding saturated com- pound. The catalytic hydrogenation conditions are known per se and do not require further explanation.

When the Wittig reaction is carried out using the above- mentioned alkyl ester, the desired polycosanol can be ob- tained by reduction of the saturated ester (after catalytic hydrogenation of the olefin), for example, using lithium alu- minium hydride in tetrahydrofuran, for 3 hours at ambient temperature with agitation.

Alternatively, the saturated ester obtained by catalytic hy- drogenation is converted into polycosanoic acid by alkaline hydrolysis.

By way of example, the hydrolysis of the ester can be carried out in accordance with the following methods: a) hydrolysis of the ester with aqueous NaOH, heating at 90OC for 2 hours; b) hydrolysis of the ester to acid with caustic potash in hydroalcoholic solution; c) hydrolysis of the ester with LiOH in hydroalcoholic solu- tion.

As indicated above, the catalytic hydrogenation reaction is preferably carried out directly on the unsaturated alkyl es- ter in view of the greater solubility of the ester in a hy- droalcoholic solvent.

The following scheme illustrates the reaction stages for the conversion of cis-trans methyl octacosenoate into octacosanol and octacosanoic acid. OCH3 97% H2 Pd/C O + MeOH Saturated ester LiAIH Aq. NaOH 90°C 95% THF 90% ou "OH OCTACOSANOL OH on OCTACOSANOIC ACID C H O zs ss 2 OCTACOSANOIC ACID C28Hs602 The scheme for the synthesis of octacosanoic acid, without protecting the undecylenic acid, is illustrated in the fol- lowing scheme. Os04 cat. OH Nô- Na104 86% 0 C, 1 H2002 0 H20/acetone PPh3 + gr BuLi 2, 1 eq, THF 0 PPh3 OH O+ d 97% >v OH OH 0 NMO: N-methylmorpholine N-oxide It will be appreciated that, in this reaction scheme, the n- alkanoic acids obtained directly can, if desired, be con- verted into corresponding alcohols by known reduction reac- tions.

On the other hand, the polycosanoic acids and particularly octacosanoic acid and the corresponding C1-C4 alkylene esters are compounds which are useful per se in view of their power- ful activity in the treatment of hypercholesterolaemia and also their powerful antithrombotic and anti-inflammatory ac- tivity.

HPLC analysis, NMR, mass spectrometry (EI-MS and CI-MS) and gas chromatographic analysis of the products obtained con- firmed the absolute purity of the samples.

In the reaction schemes given in the present description, the reaction conditions are to be understood as being by way of non-limiting example.

The preparation of octacosanoic acid and octacosanol is de- scribed further in the specific working Examples which fol- low.

Example 1-Methyl ester of undecylenic acid In a two-necked 100 ml flask, 7 ml of methanol and a spatula tip of p-toluenesulphonic acid are added to 15 g of unde- cylenic acid (81.4 mmol) dissolved in 35 ml of anhydrous toluene. The whole is heated under reflux for 8 hours with a Dean Stark or Markusson distilling apparatus separating the water of esterification. All of the glassware used has been dried beforehand in an oven at 120°C. The progress of the re- action is monitored by TLC (silica gel plates), eluant hex- ane/EtOAc 7: 3. Rf ester = 0.64.

Work-up: the product is diluted with EtOAc, washed twice with a mixture of NaHCO3/H2O 1: 1, then with H20 and saturated NaCl solution and dried over Na2SO4. 15 g (73.0 mmol) are ob- tained, (yield 93%). Any traces of starting acid can be re- moved by filtration over a bed of alumina.

Example 2-methyl 10-oxo-decanoate In a 500 ml flask, 2.5 ml of a 0.2 M solution of Os04 in toluene (0.005 eq ; 1.03 mmol) and 24.13 g of N-methyl- morpholine-N-oxide (1 eq) are added to 40.86 g of the methyl ester of undecylenic acid (0.206 mmol) dissolved in 100 ml of a 1: 1 H2O/acetone mixture. The whole is left under agitation for 15 minutes at 0°C in ice. 79.31 g of Nazi04 (1.8 eq ; 0.37 mmol) are then added in small portions over a period of 40 minutes at ambient temperature. The reaction is followed by TLC (silica gel plates), eluant hexane/EtOAc 7: 3 Rf product = 0.5.

Work-up : the product is filtered on a funnel having a sin- tered porous baffle, diluted with EtOAc, washed with a satu- rated NaCl solution and dried over Na2SO4. The product is then purified on a chromatographic column of silica gel (CC) eluant hexane/EtOAc 9: 1.35. 3 g of methyl 10-oxo-decanoate (176.6 mmol) are obtained. (Yield 86%).

Example 3-Phosphonium salt of 1-bromooctadecane In a 250 ml flask, 1 eq of triphenylphosphine (24.6 g) is added to 30 g of 1-bromooctadecane (0.09 mmol) dissolved in 80 ml of anhydrous toluene. The whole is heated under reflux in a heating jacket for 24 hours. It is then cooled in a bath of water and ice for approximately 10 minutes and then ap- proximately 15 ml of diethyl ether are added. The phosphonium salt precipitates in abundance, is filtered on a funnel hav- ing a sintered porous baffle and is washed with approximately 50 ml of ether. 41 g of a pearly pink solid (71.2 mmol) are obtained. (Yield 80%).

Example 4-Methyl ester of 10-octacosenoic acid In a 1 t two-necked flask, 32 g of phosphonium salt (56.0 mmol) are dissolved in 350 ml of anhydrous THF with magnetic agitation in a nitrogen atmosphere. All of the glassware used has been dried beforehand in an oven at 120°C. 1.05 eq of a solution of BuLi (1.6 M in hexane) (34 ml) are slowly added dropwise; the reaction mixture turns progressively orange- red, which indicates the formation of the ylide. After ap- proximately 20 minutes, 5 ml of a solution containing 10.08 g of methyl 10-oxo-decanoate (0.9 eq; 50.4 mmol) are slowly added dropwise; during the addition of the aldehyde, the col- our of the solution becomes yellow-orange. The whole is left under magnetic agitation overnight. The reaction is monitored by TLC (silica gel plates), eluant hexane/EtOAc 9: 1. Rf prod- uct = 0.65.

Work-up: the product is diluted with a 0. 1N HCl solution and extracted with EtOAc; washing is effected with a saturated NaCl solution and the whole is dried over Na2SO4. 19. 2 g of product (45.1 mmol) are obtained. (Yield 90%).

Example 5-10-octacosenoic acid In a 100 ml flask, 5 g of the methyl ester of 10-octacosenoic acid (11.8 mmol) in admixture with an aqueous 3.5N NaOH solu- tion (30 ml) are heated at 90°C for 3 hours. The reaction is monitored by TLC (silica gel plates), eluant hexane/EtOAc 8: 2. Rf product = 0.31.

Work-up: the mixture is acidified with 1N HC1 and extracted with CH2Cl2. The organic phase is washed with saturated NaCl solution and dried over Na2SO4. 4.48 g of 10-octacosenoic acid (10.6 mmol) are obtained. (Yield 90%).

Example 6-Octacosanoic acid 4.48 g of 10-octacosenoic acid (10.6 mmol) dissolved in 30 ml of methanol are subjected to catalytic hydrogenation with palladium on carbon in a Parr hydrogenator at 25 atm. and at approximately 45°C (6 hours). The whole is filtered over a bed of celite in a funnel having a sintered porous baffle and the solvent is evaporated under vacuum. TLC (silica gel plates) eluant hexane/EtOAc 8: 2. Rf product = 0. 30.4. 32 g (10.2 mmol) are obtained. (Yield 96%).

Example 7-10-octacosenol There are introduced into a 100 ml flask 8 g of the methyl ester of 10-octacosenoic acid (19.0 mmol) dissolved in 30 ml of anhydrous THF, and 1.44 g of LiAlH4 (2 eq) subdivided into two portions (the second after 2 hours). The whole is left under magnetic agitation in an N2 atmosphere for 4 hours. The reaction is monitored by TLC (silica gel plates), eluant hex- ane/EtOAc 9: 1. Rf product = 0.58.

Work-up : the mixture is acidified with 0.2N H2SO4 and ex- tracted with CH2C12. The organic phase is washed with a satu- rated NaCl solution and dried over Na2SO4. 7.36 g of product (18.0 mmol) are obtained. (Yield 95%).

Example 8-Octacosanol 7.36 g of octacosenol (18 mmol) dissolved in 30 ml of metha- nol are subjected to catalytic hydrogenation with palladium on carbon in a Parr hydrogenator at 25 atm. (6 hours). The whole is filtered over a bed of celite in a funnel having a sintered porous baffle and the solvent is evaporated under vacuum. 7.14 g (17.5 mmol) are obtained. (Yield 97%). TLC (silica gel plates) eluant hexane/EtOAc 9: 1. Rf product = 0.57.

Similarly to the Examples given above, it is possible to pre- pare the corresponding polyunsaturated compounds using-in- stead of 1-bromo-octadecane-corresponding unsaturated com- pounds, for example, cis-1-bromo-9-octadecene, 1-brom-9, 12- octadecadiene or 1-brom-9, 12,15-octadecatriene.

The unsaturated compounds have, in general, a better activity compared with the corresponding polycosanols and polycosanoic acids and can therefore be used advantageously in the pharma- ceutical, cosmetic and nutritional field (particularly for dietetic nutrition integrators), in which the polycosanols and polycosanoic acids are typically used.

These compounds have a high degree of antioxidant activity and a high degree of activity in the capture of free radi- cals, which enables them to be used both in cosmetic and nu- tritional compositions as antioxidants, in order to prevent the oxidative deterioration of those compositions, and in cosmetic and dermatological compositions for topical use, for the prevention and treatment of skin damage caused by free radicals, such as, in particular, for the treatment and pre- vention of inflammatory and ageing effects of the skin.

The unsaturated compounds are also characterized by a higher hypocholesterolaemic and/or hypolipidaemic activity in addi- tion to a favourable effect on the lipoprotein picture (in- crease in HDL) compared with the corresponding polycosanols; they are therefore suitable for use in the preparation of me- dicaments and pharmaceutical compositions that can be used for the treatment and prevention of pathologies related to hypercholesterolaemia and hyperlipidaemia, such as, for exam- ple, cardiovascular diseases of the ischaemic or atheroscle- rotic type and peripheral vascular diseases, and also for the prevention and cure of pathologies associated with an in- creased ability of blood platelets to aggregate and with a reduced oxygenation and nourishing of tissue, such as, for example, peripheral neuropathies and, in particular, diabetic peripheral neuropathy.