QUINOLIN-4-YLHYDRAZINE DERIVATIVES AS ANTIMALARIAL AGENTS

FIELD OF THE INVENTION

The present invention relates to quinolyl and acridinylhydrazone compounds, which present remarkable biological activity especially against the choloroquine-resistant Plasmodium falciparum strains, useful for the treatment and prevention of malaria infection. BACKGROUND OF THE INVENTION

Malaria is a disease of worldwide implications and almost half of the world's population is currently at risk for malaria infection. Despite significant advances in

understanding the disease and the parasite, malaria still remains one of the leading causes of morbidity and mortality, particularly in malaria-endemic regions

of the world. Over 300 million cases are reported annually and 1.5-2.5 million people die from this disease. Recent trends indicate rapid emergence of drug- resistant and more virulent strains of the parasite to further intensify the problem. Although four species of the genus Plasmodium cause human malaria,

Plasmodium falciparum is the deadliest and has high adaptability by mutation and is resistant to various types of antimalarial drugs. Chloroquine (CQ) and other quinoline antimalarials such as amodiaquine, quinine and mefloquine have been in the mainstays of malaria chemotherapy for the past 40 years. The exact mode of action of these quinoline derivatives remains to be elucidated, but most investigators accept that a crucial step in this process is the binding of the drug to ferriprotoporphyrin IX (FP), a by-product of hemoglobin (Hb) degradation. The Hb degradation pathway and the concomitant detoxification of heme are absolutely

necessary for the uninterrupted growth and proliferation of the parasite. Therefore,

the metabolic functions related to hemoglobin digestion and heme detoxification pathways may be a potential target for new antimalarial drug discovery.

Apart from quinoline-based antimalarials, antifolate and antibiotics, the peroxide artemisinin and its synthetic derivatives are increasingly used and have become very important to combat the disease. However, the current routes for

total chemical synthesis limit their commercial viability. Further, in the absence of substitute, the appearance of artemisinin-resistant malaria would lead to be a potential humanitarian disaster. Unlike parasite-encoded enzymes and transporters that are currently under investigation, the parasite has difficulty in

developing resistance to drugs that bind FP (compare the > 20 years taken for the emergence of CQ resistance with < 1 year for the resistance to pyrimethamine or atovaquone). Because of this and the ease of developing new derivatives that avoid the CQ resistance mechanism, the development of new quinoline derivatives is a valid strategy. However, the efficacy of quinoline-based antimalarials has decreased in the recent years, mainly as a result of the development and rapid spread of drug resistant P. falciparum strains. This has led to critical need to understand the mechanism of action of quinoline antimalarials and the molecular basis of CQ resistance so that novel drugs or drug combinations can be developed to circumvent the development of drug resistance. Although the molecular basis for

CQ resistance is not fully understood, it is clear that the CQ resistant parasites accumulate fewer drugs than sensitive strains. This could in principle arise by (i) alternations in the Na ⁺ /H ⁺ exchanger which results in lower rate of influx, (ii) a higher rate of efflux (by a plasmodial P-glycoproteine (P-gh-1) or by any other protein) , (iii) or a combination of both and would also be influenced by any

reduction in binding affinity of the drug for its ultimate target. While higher rate of efflux was originally proposed to be the major factor, later studies indicated that changes in uptake better explained the observed kinetics.

The presence of a mutant form of a parasite protein refer to as the Plasmodium falciparum CQ resistance transporter (P/CRT), has been shown to be

linked to CQ resistance. The level of CQ resistance is also determined by the expression of mutant forms of the P. falciparum P-glycoprotein homologue-1 (Pgh1 ). The precise roles of these proteins have not been delineated but they may function as CQ transporters that extrude CQ from its site of action in the food vacuole of CQ-resistant parasites. It is nevertheless clear that CQ resistance can not be conferred by Pgh1 alone and requires the presence of mutations in other genes (Pfcg2, Pfcrt).

Unfortunately, resistance to these common antimalarial medications cannot be overcome by increasing their dosage as they have extremely narrow therapeutic window. Thus the development of new, safe and effective antimalarials with novel mechanism of action that prevent transmission, in addition to curing patients, is urgently required towards achieving an effective control of malaria infection. DESCRIPTION OF THE INVENTION In light of the impact of resistant strains of Plasmodium we directed our

efforts toward the design and synthesis of some novel quinolyl and acridinylhydrazones. These compounds present remarkable biological activity especially against the CQ resistant strains, which is promising for the development

of a new antimalarial drug. Furthermore, the synthesis involves few steps from

commercial products with a low cost of production and addresses to the economic burden associated with this orphan disease.

Therefore the main aim of the invention is to provide the compounds for Formula (I) as follows:

(I) where:

Ri is selected from the group comprising phenyl substituted with 3-or 4- pyrrolidinyl-methyl, or 3-hydroxy-4-pyrrolidinyl-methyl, or 4-hydroxy-3-pyrrolidinyl-

methyl, or naphtyl unsubstituted or substituted with a (C1-C4) alkyl or a (C1-C4) alkoxy, 5- 6- 11- or 12-membered heterocyclyl or heteroaryl selected from the group comprising imidazolyl unsubstituted or substituted with a (C1-C4) alkyl or a (C ₁ -C ₄ ) alkoxy, pirazolyl, isoxazolyl, pyrrolyl, pyrrolidinyl, benzodioxolyl;

R2 is hydrogen or (C1-C4) alkoxy;

R3 is hydrogen, halogen or (C1-C4) alkoxy; R4 is hydrogen or (C1-C4) alkoxy R ₅ is hydrogen;

Rβ is hydrogen or taken together with R ₅ it forms a benzofused system substituted with a (CrC ₄ ) alkoxy at 6 position;

with the proviso that when Ri is naphtyl substituted, R3 is a halogen.

Compounds of Formula (I) also comprise tautomers, geometrical isomers, optically active forms as enantiomers, diastereomers and racemate forms, as well as pharmaceutically acceptable salts of the compounds of Formula (I).

Depending on the meanings of the radicals in the compounds of formula (I) one or more chiral centres (on carbon or nitrogen atoms) may be present. For the purposes of the present invention it is pointed out that each of the products of formula (I) can exist both as a racemic mixture R/S, and in the separate isomeric forms R and S.

Preferred pharmaceutically acceptable salts of the Formula (I) are acid addition salts formed with pharmaceutically acceptable acids like hydrobromide, hydrochloride, sulfate or bisulfate, phosphate or hydrogen phosphate, acetate, benzoate, succinate, fumarate, maleate, lactate, citrate, tartrate, gluconate, methanesulfonate, benzenesulfonate, and para-toluenesulfonate salts.

Suitable pharmaceutically acceptable base addition salts for the compound of the present invention include metallic salts made from aluminum, calcium, lithium, magnesium, potassium, sodium and zinc or organic salts made from lysine, N ₁ IST- dibenzylethylenediamine, chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine (N-methylglucamine) and procaine. Sodium salts are particularly preferred.

Within the framework of the present invention, examples of the (C ₁ -C ₄ ) alkyl

group, are understood to include linear or branched groups, such as methyl, ethyl, propyl and butyl as well as their possible isomers, such as, for example, isopropyl,

isobutyl, and ter-butyl. The expression "lower alkyl" is herein used as a synonym of (Ci-C ₄ ) alkyl group.

The expression "heterocyclyl", alone or in combination, means saturated or unsaturated (but not aromatic) five-, six- or seven-membered rings containing one or two nitrogen, oxygen or sulfur atoms which may be the same or different and which rings may be substituted with lower alkyl, lower alkenyl, aryl; examples of such rings are morpholinyl, piperazinyl, tetrahydropyranyl, dihydropyranyl, dioxanyl, pyrrolidinyl, tetrahydrofuranyl, dihydropyrrolyl, imidazolidinyl,

dihydropyrazolyl, pyrazolidinyl etc. and substituted derivatives of such type rings with substituents as outlined hereinbefore.

The expression "heteroaryl", alone or in combination, means six-membered

aromatic rings containing one to four nitrogen atoms; benzofused six-membered aromatic rings containing one to three nitrogen atoms; five-membered aromatic rings containing one oxygen, one nitrogen or one sulfur atom; benzo-fused

fivemembred aromatic rings containing one oxygen, one nitrogen or one sulfur atom; five membered aromatic rings containing one oxygen and one nitrogen atom and benzo fused derivatives thereof; five membred aromatic rings containing a sulfur and nitrogen or oxygen atom and benzo fused derivatives thereof; five membered aromatic rings containing three nitrogen atoms and benzo fused derivatives thereof or the tetrazolyl ring; examples of such rings are furanyl, thienyl, pyrrolyl, pyridinyl, indolyl, quinolinyl, isoquinolinyl, dihydroquinolinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, imidazolyl, triazinyl, thiazinyl,

pyridazinyl, oxazolyl, and the like, whereby such ring systems may be mono-, di-or tri-substituted with aryl; aryloxy, aryl-lower alkoxy, lower alkyl; lower alkenyl ; lower alkyl-carbonyl; amino; lower alkyl-amino; bis-(lower-alkyl)-amino; lower alkanoyl-

amino; lower alkylsulfonamido; aryl-sulfonamido, heteroaryl-sulfonamido; lower alkyl-sulfono; arylsulfono-amino-lower alkyl; halogen; hydroxy; carboxyl; lower alkoxy; vinyloxy; allyloxy-hydroxy-lower alkyl; nitro; cyano; amidino; trifluoromethyl; lower alkylsulfonyl.

"Halogen" refers to fluoro, chloro, bromo and iodo atoms.

According to the present invention Ri is preferably imidazolyl, pirazolyl, isoxazolyl, pyrrolyl, thienyl, pyrrolidinyl, benzodioxolyl, or quinolinyl all of them possibly substituted with a (CrC ₄ ) alkyl, preferably methyl.

According to the present invention R ₃ is preferably hydrogen, chlorine, ethoxy

or methoxy.

The group identified as (C _r C ₄ ) alkoxy is preferably methoxy and the group identified as (CrC ₄ ) alkyl is preferably methyl.

Particularly preferred according to the present invention are the following compounds: 2-[(1/-/-imidazol-2-yl)methylene]-1-(7-chloroquinolin-4-yl)h ydrazine (2i);

1 -(7-chloroquinolin-4-yl)-2-[(1 -methyl-1 H-imidazol-2-yl)methylene]hydrazine (2 ₂ ); 2-[(1 H-imidazol-5-yl)methylene]-1 -(7-chloroquinolin-4-yl)hydrazine (2 ₃ ); 1 -(7-chloroquinolin-4-yl)-2-[(1 -methyl-1 H-imidazol-5-yl)methylene]hydrazine (2 ₄ ); 1-(7-chloroquinolin-4-yl)-2-((3-(4-(trifluoromethyl)phenyl)1 /-/-pyrazol-4-yl)methyl) hydrazine (2 ₅ );

2-[(1 H-imidazol-4-yl)methylene]-1 -(7-chloroquinolin-4-yl)hydrazine (2 ₆ ); 1-(7-chloroquinolin-4-yl)-2-[(3,5-dimethylisoxazol-4-yl)meth ylene]hydrazine (2 ₇ ); 2-[(1 H-pyrrol-2-yl)methylene]-1 -(7-chloroquinolin-4-yl)hydrazine (2 ₈ ); 2-(4-[((pyrrolidin-1 -yl)methyl)benzylidene]-1 -(7-chloroquinolin-4-yl)hydrazine (2i 1 );

2-[(3-hydroxy-4-(pyrrolidin-1-yl)methyl)benzylidene]-1-(7 -chloroquinolin-4-

yl)hydrazine (2 ₁₂ );

2-((benzo[d][1 ,3]dioxol-6-yl)methylene)-1 -(7-chloroquinolin-4-yl)hydrazine (2i ₃ ); 2-[(4-diethylamino)methyl]benzylidene-1-(7-chloroquinolin-4- yl)hydrazine (2i ₄ ); 2-(4-pyrrolidin-1-yl)benzylidene-1-(7-chloroquinolin-4-yl)hy drazine (2 ₁₅ ); 2-(4-methoxybenzylidene)-1-(7-chloroquinolin-4-yl)hydrazine (2ie); 2-((benzo[c/][1 ,3]dioxol-5-yl)methylene-1-(7-chloro-2-methylquinolin-4-yl)h ydrazine

(22o);

2-(4-methoxybenzylidene)-1 -(7-ethoxy-2-methylquinolin-4-yl)hydrazine (2 ₂ i ); 2-(4-methoxybenzylidene)-1 -(6-methoxyquinolin-4-yl)hydrazine (2 ₂₆ );

2-[4-(diethylaminomethyl)benzylidene]-1-(6-methoxyquinolin-4 -yl)hydrazine (2 ₂₇ );

2-(4-pyrrolidin-1-yl)benzylidiene-1-(6-methoxyquinolin-4-yl) hydrazine(2 ₂ 8);

2-[4-(diethylamino)benzylidene]-1-(6-methoxyquinolin-4-yl)hy drazine (2 ₂₉ );

2-((benzo[o(][1 ,3]dioxol-6-yl)methylene-1-(6-methoxy-2-methylquinolin-4-

yl)hydrazine (2 ₃₀ );

2-(3-methoxybenzylidene)-1-(6-methoxy-2-methylquinolin-4-yl) hydrazine (2 ₃ i);

2-(2-methoxynaphthalen-1 -ylmethylene)-1 -(7-chloro-quinolin-4-yl)hydrazine (2 ₃₅ );

2-(6-chloro-2-methoxyacridin-9-yl)-1 -(1 /-/-imidazol-2-ylmethylene)hydrazine (4i );

1-(6-chloro-2-methoxyacridin-9-yl)-2-(4-pyrrolidin-1-ylmethy lbenzylidene)hydrazine (4 ₂ );

1/-/-imidazole-2-carboxylic acid λ/'-(7-chloroquinolin-4-yl)hydrazide (5i); and

3/-/-imidazole-4-carboxylic acid λ/'-(7-chloroquinolin-4-yl)hydrazide (5 ₂ ).

The compounds of Formula (I) may be prepared from readily available starting materials using the following general methods and procedures. It will be appreciated that where typical or preferred experimental conditions (i.e. reaction

temperatures, time, moles of reagents, solvents, etc.) are given, other experimental conditions can also be used, unless otherwise stated. Optimum reaction conditions may vary with the particular reactants or solvents used, but such conditions can be determined by one skilled in the art by routine optimisation procedures. Specific reference is made to the methods described in the Examples and to the Schemes 1-3.

According to a preferred embodiment of the invention, a quinolylhydrazine or a acridinylhydrazine is reacted with a carboxyaldehyde and an equimolar amount of sodium acetate in alcohol. A method of treating a mammal suffering from malaria infection or at risk of being infected, comprising administering a therapeutically effective amount of a compound of Formula (I) as described above represents one of the aspects of the present invention. The term "therapeutically effective amount" as used herein refers to an amount of a therapeutic agent needed to treat, ameliorate a targeted disease or condition, or to exhibit a detectable therapeutic effect.

For any compound, the therapeutically effective dose can be estimated initially either in cell culture assays, for example, Plasmodium falciparum strains, or in animal models, usually mice, monkeys, rabbits, dogs, or pigs.

The animal model may also be used to determine the appropriate concentration range and route of administration. Such information can then be

used to determine useful doses and routes for administration in humans.

The precise effective amount for a human subject will depend upon the severity of the disease state, general health of the subject, age, weight, and gender of the subject, diet, time and frequency of administration, drug combination

(s), reaction sensitivities, and tolerance/response to therapy. This amount can be

determined by routine experimentation and is within the judgement of the clinician. Generally, an effective dose will be from 0.01 mg/kg to 100 mg/kg, preferably 0.05 mg/kg to 50 mg/kg. Compositions may be administered individually to a patient or may be administered in combination with other agents, drugs or hormones. The medicament may also contain a pharmaceutically acceptable carrier, for administration of a therapeutic agent. Such carriers include antibodies and other polypeptides, genes and other therapeutic agents such as liposomes, provided that the carrier does not itself induce the production of antibodies harmful to the individual receiving the composition, and which may be administered without undue toxicity.

Suitable carriers may be large, slowly metabolised macromolecules such as proteins, polysaccharides, polylactic acids, polyglycolic acids, polymeric amino acids, amino acid copolymers and inactive virus particles.

A thorough discussion of pharmaceutically acceptable carriers is available in Remington's Pharmaceutical Sciences (Mack Pub. Co. , N. J.1991).

Pharmaceutically acceptable carriers in therapeutic compositions may additionally contain liquids such as water, saline, glycerol and ethanol. Additionally, auxiliary substances, such as wetting or emulsifying agents, pH

buffering substances, and the like, may be present in such compositions. Such carriers enable the pharmaceutical compositions to be formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions, and the like, for ingestion by the patient.

Once formulated, the compositions of the invention can be administered directly to the subject. The subjects to be treated can be animals; in particular, human subjects can be treated.

The medicament of this invention may be administered by any number of routes including, but not limited to, oral, intravenous, intramuscular, intra-arterial, intramedullary, intrathecal, intraventricular, transdermal or transcutaneous applications, subcutaneous, intraperitoneal, intranasal, enteral, topical, sublingual, intravaginal, rectal means or locally on the diseased tissue after surgical operation.

Dosage treatment may be a single dose schedule or a multiple dose schedule.

A further object of the present invention are pharmaceutical compositions containing one or more of the compounds of formula (I) described earlier, in combination with excipients and/or pharmacologically acceptable diluents.

The compositions in question may, together with the compounds of formula (I), contain known active principles.

The invention also includes the use of the compounds of Formula (I) for the preparation of drugs useful in the treatment and/or prevention of malaria infection. A further embodiment of the invention is a process for the preparation of

pharmaceutical compositions characterised by mixing one or more compounds of formula (I) with suitable excipients, stabilizers and/or pharmaceutically acceptable diluents.

The invention will now be illustrated in greater detail by means of non- limiting Examples. EXAMPLES Experimental Procedure

The hydrazones 2r2 ₃₅ , 4 ₁₅ 4 ₂ and hydrazides 5i,5 ₂ are reported in Tables 1- 3. The synthesis of every compound is given at the end of each table. The

synthesis of not commercially available starting material is described in the last part of this experimental section.

Example 1 - Synthesis of compounds of Formula (I) according to Scheme 1

H-R

Scheme 1. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ as defined in Table 1

Table 1

Compd R1 R2 R3 R4 R5 Mp ( ⁰ C)

CH ₃ -N H Cl H H 259 />

-N

N-.

H Cl H H 307

General Procedure for the preparation of 4-quinolylhvdrazones (2)

The title compounds were prepared from 4-quinolylhydrazine (0.1 g, 0.516 mmol), appropriate carboxaldehyde (0.516 mmol) and an equimolar amount of NaOAc in boiling EtOH (3 ml_) and refluxed for 2-3 h. After cooling and diluting

with H ₂ O the respective hydrazones precipitated from the reaction mixture, and

were filtered and washed with ice cold ethanol. The purification was carried out by crystallization and/or by flash column chromatography (70-90% yields).

2-[(1H-lmidazol-2-yl)methylene]-1-(7-chloroquinolin-4-yl) hydrazine (2i).

Compound 2i was prepared from 2-imidazolecarbaldehyde (0.0495 g, 0.516 mmol) by following the general procedure. The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 9:1 ) to give the product as yellow

amorphous solid (0.12 g, 87%). ¹ H NMR (DMSO-d ₆ ) δ 12.62 (bs, 1 H), 11.21 (s, 1 H), 8.58 (d, 1 H, J = 4.7 Hz), 8.30 (d, 1 H, J = 8.8 Hz), 8.22 (s, 1 H), 7.89 (s, 1 H),

7.59 -7.52 (m, 2H), 7.27 (s, 1 H), 7.04 (s, 1 H); Mass m/z (M+1 ) ⁺ 271. i^y-Chloroquinolin^-ylJ^-^i-methyl-IH-imidazol^-ylJmethylene lhydrazine

(22).

Compound 22 was prepared from 1-methyl-2-imidazolecarbaldehyde (0.0568 g, 0.516 mmol) by a similar procedure to that described for The crude product was recrystallized from MeOH to afford the product as yellow amorphous solid (0.13 g, 89%). ¹ H NMR (DMSO-d ₆ ) δ 11.19 (bs, 1 H), 8.35-8.27 (m, 3H), 7.87 (s,1 H), 7.50 (d, 1 H, J = 8.6), 7.31 (s, 1 H), 7.11 (d, 1 H, J = 5.5 Hz), 7.01 (s,1 H), 3.97 (s, 3H); ESI MS m/z (M+1) ⁺ 286.

2-[(1H-lmidazol-5-yl)methylene]-1-(7-chloroquinolin-4-yl) hydrazine (23).

Compound 2 ₃ was prepared from 4(5)- imidazolecarbaldehyde (0.0495 g, 0.516 mmol) by a similar procedure to that described for 2-|. The crude product was purified by column chromatography (CH ₂ C^MeOH/ NH ₄ OH 9:1 :0.01) to give

the product as yellow amorphous solid. (0.119 g, 85%). ¹ H NMR (DMSO-d ₆ ) δ 11.75 (s, 1 H), 8.37-8.27 (m, 4H), 7.77- 7.75 (m, 2H), 7.51-7.45 (m, 2H), 7.27 (d, 1 H, J = 5.4 Hz); ESI MS m/z (M+1 ) ⁺ 272.

i^y-Chloroquinolin^-ylJ^-^i-methyl-IH-imidazol-S-ylJmethy lenelhydrazine

(24).

Compound 2_ι was prepared from i-methyl-I H-imidazole-5-carbaldehyde (0.0568 g, 0.516 mmol) by a similar procedure to that described for The crude product was recrystallized from MeOH to afford the product as yellow amorphous solid (0.119 g, 81%) ¹ H NMR (DMSO-d ₆ ) δ 11.00 (bs, 1 H), 8.36 (s,1 H), 8.28 (d, 2H, J = 8.9 Hz), 7.75 (s, 2H), 7.46 (d, 1 H, J = 8.7 Hz), 7.31 (s, 1 H), 7.06 (d, 1 H, J = 5.6 Hz), 3.92 (s, 3H); ESI MS m/z (M+1 ) ⁺ 286. 1-(7-Chloroquinolin-4-yl)-2-((3-(4-(trifluoromethyl)phenyl)1 H-pyrazol-4- yl)methyl)hydrazine (2 ₅ )

Compound 2 ₅ was obtained from 3-[4-(trifluoromethyl)phenyl]-1/-/-pyrazole- 4-carbaldehyde (0.124 g, 0.516 mmol) by a similar procedure as described for 2-ι. The crude product was purified by recrystallization from EtOH to afford the product as yellow amorphous solid (0.19 g, 90%). ¹ H NMR (DMSO-d ₆ ) δ 10.92 (bs, 1 H), 8.44 (s, 2H), 8.25 (d, 2H, J = 8.6 Hz), 7.92-7.83 (m, 5H), 7.49 (s, 1 H), 7.13 (s, 1 H); ESI MS m/z (M+1 ) ⁺ 416 2-[(1H-lmidazol-4-yl)methylene]-1-(7-chloroquinolin-4-yl)hyd razine (2 ₆ ).

Compound 2e was obtained from 1H-imidazole-4-carbaldehyde (0.0495 g, 0.516 mmol) by a similar procedure as described for The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 8:2) to give the product as

yellow amorphous solid (0.098 g, 70%). ¹ H NMR (DMSO-d ₆ ) δ 10.99 (bs, 1 H), 8.33 (bs, 1 H), 8.31-8.26 (m, 3H), 7.76 (s, 1 H), 7.72 (s, 1 H), 7.49 (s, 1 H), 7.46 (d, 1 H, J = 9.3 Hz), 7.44 (s, 1 H), 7.26 (d, 1 H, J = 5.4 Hz); ESI MS m/z (M+1 ) ⁺ 272.

i^y-Chloroquinolin^-ylJ^-^S.S-dimethylisoxazol^-ylJmethyl enelhydrazine

(2 ₇ ).

Compound 2 ₇ was obtained from 3,5-dimethyl-4-isoxazolecarbaldehyde (0.0645 g, 0.516 mmol) by a similar procedure as described for The crude product was purified by recrystallization from EtOH to give the product as yellow

amorphous solid (0.124 g, 80%). ¹ H NMR (DMSO-d ₆ ) δ 11.05 (bs, 1 H), 8.50-8.23 (m, 3H), 7.75 (s, 1 H), 7.48 (d, 1 H, J = 9.1 Hz), 7.06 (d, 1 H, J = 5.5 Hz), 2.52 (s, 3H), 2.46 (s, 3H); ESI MS m/z (M+1 ) ⁺ 301.

2-[(1H-Pyrrol-2-yl)methylene]-1-(7-chloroquinolin-4-yl)hydra zine (2s). Compound 2 ₈ was obtained from 1 H-pyrrole-2-carbaldehyde (0.049 g,

0.516 mmol) by a similar procedure as described for 2< _\ . The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 9:0.05) to give the product as

yellow amorphous solid (0.10 g, 72%). ¹ H NMR (DMSO-d ₆ ): δ 11.11 (bs,1 H), 8.30- 8.24 (m, 4H), 7.78 (s, 2H), 7.47 (d, 1 H, J = 7.99 Hz), 7.16 (s, 1 H), 6.86 (d, 1 H, J = 3.41 Hz), 6.61 (d, 1 H, J = 1.78 Hz); ESI MS m/z (M+1 ) ⁺ 271.

2-(4-[((Pyrrolidin-1-yl)methyl)benzylidene]-1-(7-chloroqu inolin-4-yl)hydrazine

(2ii).

Compound 2-n was obtained from 4-(tetrahydro-1 H-1 pyrrolylmethyl)

benzaldehyde (0.0975 g, 0.516 mmol) by a similar procedure as described for The crude product was purified by recrystallization from ethanol to afford the product as yellow amorphous solid (0.145 g, 77%). ¹ H NMR (DMSO-d ₆ ): δ 11.12 (s, 1 H), 8.35-8.31 (m, 3H), 7.79 (s, 1 H), 7.69 (d, 2H, J = 7.94 Hz), 7.49 (d, 1 H, J = 8.5 Hz), 7.36-7.27 (m, 3H), 3.56 (s, 2H), 2.50-2.31 (m, 4H), 1.75-1.66 (m, 4H); ESI

MS m/z (M+1 ) ⁺ 365.

2-[(3-Hydroxy-4-(pyrrolidin-1-yl)methyl)benzylidene]-1-(7 -chloroquinolin-4-

yl)hydrazine (2i ₂ ).

Compound 2i2 was obtained from 3-hydroxy-4-(tetrahydro-1 H-1- pyrrolylmethyl) benzaldehyde (0.106 g, 0.516 mmol) by a similar procedure as described for 2-|. The crude product was purified by column chromatography

(EtOAc/MeOH 9:0.05) to afford the product as yellow amorphous solid (0.141g, 72%). ¹ H NMR (CD ₃ OD): δ 8.44 (d, 1 H, J = 5.4 Hz), 8.22 (s, 1 H), 8.17-8.15 (m, 2H), 7.67 (d, 1 H, J = 1.7 Hz), 7.47-7.41 (m, 2H), 7.18 (s, 1 H), 7.12 (s, 1 H), 3.87 (s,

2H), 2.71-2.61 (m, 4H), 1.98-1.86 (m, 4H); ESI MS m/z (M+ 1) ⁺ 381. 2-((Benzo[d][1 ,3]dioxol-6-yl)methylene)-1 -(7-chloroquinolin-4-yl)hydrazine

Compound 2i3 was obtained from 1 ,3-benzodioxole-5-carbaldehyde (0.077 g, 0.516 mmol) by a similar procedure as described for The crude product was recrystallized from ethanol to afford the product as yellow amorphous solid (0.116 g, 70%). ¹ H NMR (DMSO-d ₆ ): δ 11.80 (bs, 1 H), 8.34-8.23 (m, 2H), 7.85 (s, 1 H), 7.48 (d, 1 H, J = 8.4 Hz), 7.39 (s, 1 H), 7.27 (bs, 1 H), 7.17 (d, 2H, J = 8.3 Hz), 6.96 (d, 1 H, J = 8.0 Hz), 6.06 (s, 2H); ESI MS m/z (M+1 ) ⁺ 326.1. 2-[(4-Diethylamino)methyl]benzylidene-1-(7-chloroquinolin-4- yl)hydrazine

(214). Compound 2 ₁₄ was obtained from 4-[(diethylamino)methyl] benzaldehyde

(0.098 g, 0.516 mmol) by a similar procedure as described for 2-ι. The crude product was purified by column chromatography (CH ₂ Cl ₂ /MeOH 97:3) to afford the product as yellow amorphous solid (0.14g, 75%). ¹ H NMR (CDCI ₃ ): δ 8.54 (d, 1 H, J = 5.3 Hz), 8.12 (s, 1 H), 7.95 (d, 2H, J = 8.9 Hz), 7.62 (d, 2H, J = 7.9 Hz), 7.40-

7.34 (m, 4H), 4.69 (bs, 1 H), 3.6 (s, 2H), 2.57 (q, 4H, J = 7.1 Hz), 1.07 (t, 6H, J = 7.0 Hz); ESI MS m/z (M+1 ) ⁺ 367.1. 2-(4-Pyrrolidin-1-yl)benzylidene-1 -(7-chloroquinolin-4-yl)hydrazine (2i ₅ ).

Compound 2-ι ₅ was obtained from 4-tetrahydro-1 H-1-pyrrolyl benzaldehyde (0.0903 g, 0.516 mmol) by a similar procedure as described for 2-|. The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 90:10) to afford

the product as yellow amorphous solid (0.144 g, 80%). ¹ H NMR (DMSO-d ₆ ): δ 10.85 (bs, 1 H), 8.49 (d, 1 H, J = 4.9 Hz), 8.31 (d, 1 H, J = 8.9 Hz), 8.23 (s, 1 H), 7.82 (s, 1 H), 7.57-7.48 (m, 3H), 7.26 (d, 1 H, J = 5.0 Hz), 6.56 (d, 2H, J = 8.3 Hz), 3.27- 3.25 (m, 4H), 2.46-1.96 (m, 4H); ESI MS m/z (M+1) ⁺ 351.

2-(4-Methoxybenzylidene)-1-(7-chloroquinolin-4-yl)hydrazi ne (2iε).

Compound 2i6 was obtained from 4-methoxy benzaldehyde (0.070 g, 0.516 mmol) by a similar procedure as described for The crude product was recrystallized from ethanol to afford the product as yellow amorphous solid (0.124 g, 78%). ¹ H NMR (DMSO-d ₆ ): δ 11.0 (bs, 1 H), 8.52 (bs, 1 H), 8.34-8.31 (m, 3H), 7.84 (s, 1 H), 7.70 (d, 2H, J = 8.6 Hz), 7.52 (d, 1 H, J = 6.84 Hz), 6.98 (d, 2H, J = 8.6 Hz), 3.78 (s, 3H); ESI MS m/z (M+1 ) ⁺ 312.0.

2-((Benzo[c/][1,3]dioxol-5-yl)methylene-1-(7-chloro-2-met hylquinolin-4-

yl)hydrazine (2 ₂₀ ). Compound 2 ₂ o was obtained from 1 ,3-benzodioxole-5-carbaldehyde (0.077 g, 0.516 mmol) by a similar procedure as described for 2-ι. The crude product was recrystallized from ethanol to afford the product as yellow amorphous solid (0.127 g, 73%). ¹ H NMR (DMSO-d ₆ ): δ 11.0 (bs, 1 H), 8.27 (s, 2H), 7.77 (s, 1 H), 7.47 (d, 1 H, J = 8.2 Hz), 7.44 (d, 1 H, J = 1.0 Hz), 7.28 (s, 1 H), 7.18 (d, 1 H, J = 7.8 Hz), 6.98 (d, 1 H, J = 7.9 Hz), 6.08 (s, 2H), 2.54 (s, 3H); ESI MS m/z (M+1 ) ⁺ 340.2.

2-(4-Methoxybenzylidene)-1-(7-ethoxy-2-methylquinolin-4-yl)h ydrazine (2 ₂ i).

Compound 2 ₂ i was obtained from 4-methoxy benzaldehyde (0.070 g, 0.516 mmol) by a similar procedure as described for 2-ι. The crude product was recrystallized from ethanol to afford the product as yellow amorphous solid (0.132 g, 77%). ¹ H NMR (DMSO-d ₆ ): δ 11.52 (bs, 1 H), 8.65 (s, 1 H), 8.57 (d, 1 H, J = 8.9 Hz), 7.77 (d, 2H, J = 7.9 Hz), 7.37-7.12 (m, 3H), 7.02 (d, 2H, J = 8.0 Hz), 4.16 (q, 2H, J = 6.7 Hz), 3.81 (s, 3H), 2.63 (s, 3H), 1.39 (t, 3H, J = 6.6 Hz); ESI MS m/z (M+1 ) ⁺ 336. 2-(4-Methoxybenzylidene)-1-(6-methoxyquinolin-4-yl)hydrazine (2 ₂ e). Compound 2 ₂ e was obtained from 4-methoxy benzaldehyde (0.070 g, 0.516 mmol) by a similar procedure as described for 2< _\ . The crude product was purified by column chromatography (CH ₂ C^MeOH 90:10) to afford the product as yellow

amorphous solid (0.134 g, 85%). ¹ H NMR (DMSO-d ₆ ): δ 10.74 (bs, 1 H), 8.32-8.59 (bs, 2H), 7.76-7.62 (m, 4H), 7.32-7.28 (m, 2H), 7.0 (d, 2H, J = 8.1 Hz), 3.90 (s,

3H), 3.79 (s, 3H); ESI MS m/z (M+1 ) ⁺ 308.

2-[4-(Diethylaminomethyl)benzylidene]-1-(6-methoxyquinoli n-4-yl)hydrazine

(2 ₂₇ ).

Compound 2 ₂₇ was obtained from 4-[(diethylamino)methyl] benzaldehyde (0.091 g, 0.516 mmol) by a similar procedure as described for The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 90:10) to afford

the product as yellow amorphous solid (0.147g, 79%). ¹ H NMR (CDCI ₃ ): δ 8.55 (d, 1 H, J = 4.8 Hz), 8.07 (s, 1 H), 7.93 (d, 1 H, J = 9.0 Hz), 7.66 (d, 2H, J = 7.6 Hz), 7.47-7.25 (m, 3H), 7.16 (d, 2H, J = 12.0 Hz), 5.23 (bs, 1 H), 3.88 (s, 3H), 3.58 (s, 2H), 2.53 (q, 4H, J = 6.9 Hz), 1.05 (t, 6H, J = 7.0 Hz); ESI MS m/z (M+1 ) ⁺ 363.

2-(4-Pyrrolidin-1-yl)benzylidiene-1-(6-methoxyquinolin-4- yl)hydrazine(228)-

Compound 2 ₂ β was obtained from 4-tetrahydro-1 H-1-pyrrolyl benzaldehyde (0.09 g, 0.516 mmol) by a similar procedure as described for 2i. The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 90:10) to afford the product as yellow amorphous solid (0.144 g, 81 %). ¹ H NMR (DMSO-d ₆ ): δ 11.25 (bs, 1 H), 8.28 (bs, 2H), 7.75-7.65 (m, 3H), 7.57 (d, 1 H, J = 8.5 Hz), 7.34-7.22 (m, 2H), 6.58 (d, 2H, J = 8.4 Hz), 3.90 (s, 3H), 3.29-3.25 (m, 4H), 2.04-1.95 (m, 4H); ESI MS m/z (M+1 ) ⁺ 348. 2-[4-(Diethylamino)benzylidene]-1-(6-methoxyquinolin-4-yl)hy drazine (2 ₂ g).

Compound 2 ₂ g was obtained from 4-(diethylamino) benzaldehyde (0.091 g,

0.516 mmol, lequiv) by a similar procedure as described for 2-|. The crude product was purified by column chromatography (CH ₂ C^MeOH 90:10) to afford the product as yellow amorphous solid (0.135 g, 76%). ¹ H NMR (DMSO-d ₆ ): δ 11.20 (bs, 1 H), 8.45 (s, 1 H), 8.38-8.33 (m, 1 H), 7.85-7.81 (m, 2H), 7.56 (d, 2H, J = 8.5 Hz), 7.36 (d, 1 H, J = 2.0 Hz), 7.31-7.26 (m, 1 H), 6.70 (d, 2H, J = 8.4 Hz), 3.93 (s, 3H), 3.37 (q, 4H, J = 6.7 Hz), 1.10 (t, 6H, J = 6.5 Hz); ESI MS m/z (M+1 ) ⁺ 349. 2-((Benzo[d][1,3]dioxol-6-yl)methylene-1-(6-methoxy-2-methyl quinolin-4-

yl)hydrazine (2 ₃₀ )

Compound 2 ₃₀ was obtained from 1 ,3-benzodioxole-5-carbaldehyde (0.077 g, 0.516 mmol) by a similar procedure as described for 2-|. The crude product was recrystallized from ethanol to afford the product as yellow amorphous solid (0.134 g, 78%). ¹ H NMR (DMSO-d ₆ ): δ 12.50 (bs, 1 H), 8.82 (s, 1 H), 8.17 (d, 1 H, J = 2.1 Hz), 7.89 (d, 1 H, J = 9.13 Hz), 7.56 (d, 1 H, J = 2.4 Hz), 7.48 (d, 2H, J = 13.5 Hz),

7.20 (d, 1 H, J = 7.8 Hz), 6.99 (d, 1 H, J = 8.1 Hz), 6.10 (s, 2H), 3.96 (s, 3H), 2.69 (s, 3H); ESI MS m/z (M+1 ) ⁺ 336.

2-(3-Methoxybenzylidene)-1-(6-methoxy-2-methylquinolin-4- yl)hydrazine

Compound 231 was obtained from 4-methoxy benzaldehyde (0.07 g, 0.516 mmol) by a similar procedure as described for The crude product was purified by column chromatography (CH ₂ CI ₂ /Me0H 90:10) to afford the product as yellow

amorphous solid (0.133 g, 81 %). ¹ H NMR (DMSO-d ₆ ): δ 12.20 (bs, 1 H), 8.81 (s, 1 H), 8.12 (d, J=2.4 Hz, 1 H), 7.87 (d, 2H, J = 9.0 Hz), 7.78 (d, 2H, J = 8.7 Hz), 7.52 (dd, J ₁ = 2.5 Hz, J ₂ = 9.5 Hz, 1 H), 7.37 (s, 1 H), 7.03 (d, 1 H, J = 8.6 Hz), 3.96 (s, 3H), 3.81 (s, 3H), 2.66 (s, 3H); ESI MS m/z (M+1 ) ⁺ 322.

2-(2-Methoxynaphthalen-1-ylmethylene)-1-(7-chloro-quinoli n-4-yl)hydrazine

(2 ₃₅ ).

Compound 234 was obtained from 2-methoxynaphthalene-1-carbaldehyde (0.480 g, 2.58 mmol) by a similar procedure as described for The crude product was recrystallized from ethanol to afford the product as yellow solid (0.697 g, 75%). ¹ H NMR (DMSO-d ₆ ): δ 11.23 (s, 1 H), 9.30 (d, 1 H, J= 8.6 Hz), 9.13 (s, 1 H), 8.54 (s, 1 H), 8.43 (d, 1 H, J= 8.9 Hz), 8.01-7.83 (m, 2H), 7.67-7.37 (m, 4H), 7.27 (s, 1 H), 4.00 (s, 3H); ESI MS m/z (M+1 ) ⁺ 362.

Example 2 - Synthesis of compounds of Formula (I) according to Scheme 2

Scheme 2. R as defined in Table 2.

Table 2.

Compd Mp ( ⁰ C)

General Procedure for the preparation of 9-acridinylhydrazones (4).

The title compounds were prepared following the general procedure described for compound (2).

2-(6-Chloro-2-methoxyacridin-9-yl)-1-(1H-imidazol-2-ylmet hylene)hydrazine

(4i).

Compound 4ι was obtained from 2-imidazole carbaldehyde (0.035 g, 0.365 mmol) by following the general procedure. The crude product was purified by column chromatography (Hexane/EtOAc 1 :1 ) to give the product as an orange amorphous solid (0.114 g, 89%). ¹ H NMR (DMSO-d ₆ ): δ 12.72 (bs, 1 H), 10.81 (d,

1 H, J = 19.6 Hz), 9.14 (d, 1 H, J = 9.1 Hz), 8.51 (d, 1 H, J = 1 .7 Hz), 8.33-8.28 (m,

1 H), 8.22 (s, 1 H), 7.85 (s, 1 H), 7.30-6.94 (m, 4H), 3.98 (s, 3H); ESI MS m/z (M+1 ) ⁺ 352. i-fβ-Chloro^-methoxyacridin-θ-yl^-^-pyrrolidin-i- ylmethylbenzylidene)hydrazine (4 ₂ ) Compound 4 ₂ was obtained from 4-(tetrahydro-1 H-1-pyrrolylmethyl)

benzaldehyde (0.0689 g, 0.365 mmol) by a similar procedure as described for 4|. The crude product was purified by column chromatography (CH ₂ C^MeOH 9:1) to give the product as an orange amorphous solid (0.139 g, 87%). ¹ H NMR (CDCI ₃ ): 5 8.51 (s, 1 H), 7.81 (d, 2H, J = 7.8 Hz), 7.42 (d, 2H, J = 7.8 Hz), 7.10-6.92 (m, 7H),

3.86 (s, 3H), 3.56 (s, 2H), 2.56-2.53 (m, 4H), 1.82-1.81 (m, 4H); ESI MS m/z (M+1 ) ⁺ 445 Example 3 - Synthesis of compounds of Formula (I) according to Scheme 3

Table 3.

Compd R1 Mp ( ⁰ C)

General Procedure for the preparation of 4-quinolylhvdrazides (5).

To a stirred solution of compound 1 (0.8 g, 4.13 mmol) in 2 ml_ of dry DMF was added the appropriate carboxylic acid (0.462 g, 4.13 mmol) and the resulting solution was cooled to O ⁰ C. HOBt (0.558 g, 4.13 mmol) was added and the reaction was allowed to stir at 0 ⁰ C for 30 min.

Thereafter, λ/-methylmorpholine (.915 ml_, 8.262 mmol) was added at the above temperature and the stirring was continued for 1 h. EDCI (3.168 g, 16.525 mmol) was added to the above mixture while maintaining the temperature at 0 ⁰ C, the reaction was allowed to stir for 1 h and thereafter for 14h at room temperature.

Water (25 ml_) was added to quench the reaction and the resulting solution

was extracted with 3 x 20 m L of EtOAc.

The organic layers were mixed and dried over Na ₂ SO ₄ , the solvent was evaporated and the residue was purified by column chromatography to yield the desired product. IH-lmidazole-2-carboxylic acid /V'-(7-chloroquinolin-4-yl)hydrazide (5i).

Compound 5i was obtained from I H-2-imidazolecarboxylic acid (0.462 g,

4.13 mmol, 1 equiv) by following the general procedure for 4-quinolylhydrazides. The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 8:2) to

afford the solid product (1.02 g, 86%). ¹ H NMR (DMSO-d ₆ ): δ 13.18 (bs, 1 H), 10.65 (bs, 1 H), 9.42 (bs, 1 H), 8.39 (bs, 1 H), 8.27 (d, 1 H, J = 8.9 Hz), 7.49 (d, 2H, J = 8.1 Hz), 7.33 (bs, 2H), 6.50 (bs, 1 H); ESI MS m/z (M+1 ) ⁺ 288.

3H-lmidazole-4-carboxylic acid /V'-(7-chloroquinolin-4-yl)hydrazide (5 ₂ ). Compound 5 ₂ was obtained from IH-5-imidazolecarboxylic acid (0.462 g,

4.13 mmol) by a similar procedure as described for 5-ι. The crude product was purified by column chromatography (CH ₂ CI ₂ /MeOH 8:2) to afford the solid product (1.0 g, 85%). ¹ H NMR (DMSO-d ₆ ): δ 12.56 (bs, 1 H), 10.24 (bs, 1 H), 9.61 (bs, 1 H), 8.41 (bs, 1 H), 8.28 (d, 1 H, J = 8.8 Hz), 7.79-7.76 (m, 3H) 7.48 (d, 1 H, J = 8.0 Hz), 6.51 (bs, 1 H); ESI MS m/z (M+1 ) ⁺ 288.

Preparation of not Commercially Available Aldehydes Reported for the Synthesis of Compounds 2r2 ₃₅ and 4|

R = a) — N J] b) -NEt ₂

Scheme 4. (i) Pyrrolidine or diethylamine, K ₂ CO ₃ , 18-crown-6, acetone, 55-60 ⁰ C, 4h; (ii) LAH, THF, O ⁰ C to r.t., 1.5h; (iii) MnO ₂ , dioxane, 8O ⁰ C, 1 h

Methyl 4-(tetrahydro-1H-1 pyrrolylmethyl) benzoate (7a).

To a solution of freshly distilled pyrrolidine (0.403 g, 5.67 mmol) in dry acetone (10 ml_) anhydrous K ₂ CO ₃ (1.8 g, 13.1 mmol) and 18-crown-6 (catalytic amount) were added, and the mixture was stirred at 55-60 ⁰ C for 2h. Thereafter, a

solution of 6 (1.0 g, 4.36 mmol) in dry acetone (10 ml_) was added dropwise and the mixture was stirred at the same temperature for 2h. The reaction mixture was filtered and dried in vacuo. The resulting residue was dissolved in EtOAc and the solution was washed with H ₂ O, the organic layer was dried on Na ₂ SO ₄ and concentrated in vacuo, the crude product was purified by flash chromatography (EtOAc/Hexane 3:1 ) to afford 7a as an oil (0.81 g, 85%); ¹ H NMR (CDCI ₃ ): δ 7.97 (d, 2H, J = 8.1 Hz), 7.41 (d, 2H, J = 7.9 Hz), 3.88 (s, 3H), 3.68 (s, 2H), 2.65-2.45 (m, 4H), 1.90-1.79 (m, 4H); ESI MS m/z (M+1 ) ⁺ 220. Methyl 4-[(diethylamino)methyl] benzoate (7b).

This was prepared from 6 (1.0 g, 4.36 mmol) using freshly distilled diethylamine(0.142 g, 5.676 mmol) by a similar procedure as described for 7a. Yield (0.848 g, 87%); ¹ H NMR (CDCI ₃ ): δ 7.93 (d, 2H, J = 8.0 Hz), 7.36 (d, 2H, J = 8.1 Hz), 3.85 (s, 3H), 3.55 (s, 2H), 2.46 (q, 4H, J = 7.2 Hz), 0.97 (t, 6H, J = 7.1 Hz); ESI MS m/z (M+1 ) ⁺ 222.

4-(Tetrahydro-1H-1-pyrrolylmethyl)phenyl]methanol (8a).

To a stirred solution of LAH (0.5 g, 14.21 mmol) in dry THF (10 ml_) at 0 ⁰ C was added dropwise solution of 7a (1.55 g, 7.105 mmol) in 5 ml_ dry THF. The mixture was stirred at room temperature for 1.5 h and then cooled to 0 ⁰ C. The solution was then quenched by adding cold water (4 ml_) and the resulting suspension was stirred for 30 min, diluted with ether, filtered through celite and concentrated under reduced pressure. The residue was dissolved in EtOAc and the solution was washed with H ₂ O, organic layer was dried over Na ₂ SO ₄ and concentrated in vacuo. The crude material was purified by column chromatography (CH ₂ CI ₂ /MeOH/NH ₄ OH 9:1 :0.01 ) to give 8a as an oil (1.1 g, 84%);

¹ H NMR (CDCI ₃ ): δ 7.33-7.24 (m, 4H), 4.63 (s, 2H), 3.59 (s, 2H), 2.52-2.46 (m,

5H), 1.79-1.72 (m, 4H); ESI MS m/z (M+1) ⁺ 192.

{4-[(Diethylamino)methyl]phenyl}methanol (8b).

This was prepared from 7b (0.80 g, 3.62 mmol) by a similar procedure as described for 8a. Yield (0.72 g, 83%); ¹ H NMR (CDCI ₃ ): δ 7.29-7.15 (m, 4H), 4.57

(s, 2H), 3.56 (s, 2H), 2.45 (q, 4H, J = 7.1 Hz), 1.05 (t, 6H, J = 7.0 Hz); ESI MS m/z

(M+1 ) ⁺ 194.

4-(Tetrahydro-1H-1-pyrrolylmethyl)benzaldehyde (9a).

A solution of 8a (0.325 g, 1.70 mmol) and manganese dioxide (1.48 g, 17.01 mmol) in dioxane (1.5 ml_) was stirred at 80 ⁰ C for 1 h. The reaction mixture was diluted with CH ₂ CI ₂ (50 ml_) and filtered over celite. The filtrate was concentrated to afford 9a as an oil (0.275 g, 85%). This aldehyde was used without further purification. ¹ H NMR (CDCI ₃ ): δ 9.98 (s, 1 H), 7.82 (d, 2H, J = 7.8

Hz), 7.50 (d, 2H, J = 7.9 Hz), 3.68 (s, 2H), 2.54-2.48 (m, 4H), 1.78-1.76 (m, 4H); ESI MS m/z (M+1 ) ⁺ 190

4-[(Diethylamino)methyl]benzaldehyde (9b).

This was prepared from 9b (0.70 g, 3.62 mmol) by a similar procedure as described for 9a and was used immediately without further purification. Yield (0.58 g, 84%); ¹ H NMR (CDCI ₃ ): δ 9.92 (s, 1 H), 7.76 (d, 2H, J = 8.1 Hz), 7.43 (d, 2H, J = 8.0 Hz), 3.52 (s, 2H), 2.43 (q, 4H, J = 6.9 Hz), 0.96 (t, 6H, J = 6.9 Hz); ESI MS m/z

(M+1 ) ⁺ 192.

Scheme 5. (i) H ₂ SO ₄ , MeOH, 6O ⁰ C, 3h; (ii) Ac ₂ O, pyridine, r.t, 2h; (iii) NBS, AIBN, CCI ₄ , reflux, 3.5h; (iv) Pyrrolidine, K ₂ CO _3, 18-crown-6, 55-60 ⁰ C, 3h;(v) LAH, THF, O ⁰ C to r.t, 1.5h; (vi) MnO ₂ , dioxane, 8O ⁰ C, 1 h,

Methyl 3-hydroxy-4-methylbenzoate (11). To a solution of 10 (2.0 g, 13.15 mmol) in MeOH (20 ml_) was added drop wise cone. H ₂ SO ₄ (1.5 ml_). The solution was stirred at 60 ⁰ C for 3 h. Thereafter, the solvent was removed under reduced pressure and the residue was dissolved in EtOAc, washed with saturated solution of NaHCO3, H ₂ O, dried over Na ₂ SO ₄ and concentrated in vacuo to afford 11 as an oil (1.6 g, 76%); ¹ H NMR (CDCI ₃ ): δ 7.58 (s, 1 H), 7.57-7.46 (m, 1 H), 7.24-7.12 (m, 1 H), 6.10 (s, 1 H), 3.88 (s, 3H), 2.88(s, 3H).

Methyl 3-acetyloxy-4-methylbenzoate (12).

A solution of 11 (0.25 g, 1.50 mmol) in pyridine (1 ml_) was treated with acetic anhydride (0.64 ml_, 6.77 mmol). The resulting solution was stirred for 2 h at room temperature. The pyridine and Ac ₂ O were removed under reduced pressure to afford an oily residue. The mixture was dissolved in EtOAc and the solution was

washed with H ₂ O, organic layer was dried over Na ₂ SO ₄ and concentrated in vacuo. The product 12 was obtained as an oil (0.28 g, 90%); ¹ H NMR (CDCI ₃ ): δ 7.81-7.65 (m, 2H), 7.26 (d, 1 H, J = 8.0 Hz), 3.79 (s, 3H), 2.23 (s, 3H), 2.12 (s, 3H); ESI MS m/z (M+1 ) ⁺ 209. Methyl 3-acetyloxy-4-(bromomethyl)benzoate (13).

To a solution of compound 11 (0.30 g, 1.45 mmol) dissolved in dry CCI ₄ (7 ml_) was added NBS (0.258 g, 1.45 mmol) and AIBN (catalytic amount). The solution was refluxed for 3.5 h. After the succinimide was filtered off, the solvent was evaporated to afford 13 (0.39 g, 94%) as a semisolid product. ¹ H NMR (CDCI ₃ ): δ 7.90-7.82 (m, 2H), 7.75-7.43 (m, 1 H), 4.38 (s, 2H), 3.87 (s, 3H), 2.36 (s, 3H); ESI MS m/z (M+1 ) ⁺ 288.

Methyl 3-hydroxy-4-(tetrahydro-1H-1-pyrrolylmethyl)benzoate (14).

This compound was prepared from 13 (0.35 g, 1.22 mmol) by a similar procedure to that described for 7a. The crude material was purified by column chromatography (EtOAc/Hexane 3:2 ) to give 14 as an oil (0.11 g, 40%); ¹ H NMR (CDCI ₃ ): δ 9.87 (bs, 1 H), 7.44-7.39 (m, 2H), 7.25-6.98 (m, 1 H), 3.85 (s, 3H), 2.70- 2.55 (m, 2H), 1.90-1.76 (m, 2H); ESI MS m/z (M+1 ) ⁺ 236.1. 5-(Hydroxymethyl)-2-(tetrahydro-1 H- 1 pyrrolylmethyl)phenol (15).

This compound was prepared from 14 (0.11 g, 0.468 mmol) by a similar procedure to that described for 8. The crude material was purified by column chromatography (CH ₂ CI ₂ /MeOH/NH ₄ OH 9:1 :0.05 ) to give 15 as an oil (0.73 g,

75%); ¹ H NMR (CDCI ₃ ): δ 6.97-6.90 (m, 1 H), 6.80-6.59 (m, 2H), 6.32 (bs, 1 H), 4.55 (s, 2H), 3.75 (s, 2H), 2.70-2.52 (m, 5H), 1.92-1.73 (m, 4H); ESI MS m/z

(M+1 ) ⁺ 208.

3-Hydroxy-4-(tetrahydro-1H-1-pyrrolylmethyl)benzaldehyde (16).

This aldehyde was prepared from 15 (0.07 g, 0.338 mmol) by a similar procedure to that described for 9 and was used immediately for the next step without further purification.

17 18

Scheme 6. (i) Pyrrolidine, Pd ₂ (dba) ₃ , BINAP, NaO ¹ Bu, dry toluene, 7O ⁰ C, 1 h

4-Tetrahydro-1 H-1 -pyrrolylbenzaldehyde (18).

To a freshly dried two neck round bottom flask was charged a mixture of 4- bromobenzaldehyde (17) (1.0 g, 5.4 mmol), pyrrolidine (0.383 g, 5.4 mmol), Tris(dibenzylideneacetone)dipalladium(0) (0.098 g, 0.108 mmol), (±)-BINAP (0.134 g, 0.216 mmol) and NaO-f-Bu (0.78 g, 8.10 mmol). The flask was degased and flushed with argon. Dry toluene (10 ml_) was added and the reaction mixture was stirred at 7O ⁰ C for 1 h, when the TLC showed the disappearence of the starting aldehyde. The solvent was removed under reduced pressure to afford the oily residue, which was purified by flash chromotography ( EtOAc/Hexane 3:5 ) to yield 18 as an oil (0.66 g, 70%). ¹ H NMR (CDCI ₃ ): δ 9.75 (s, 1 H), 7.70 (d, 2H, J = 8.1 Hz), 6.55 (d, 2H, J = 7.9 Hz), 3.47-3.32 (m, 4H), 2.15-2.02 (m, 4H); ESI MS m/z (M+1 ) ⁺ 176.

Example 4 - Pharmacological results

The hydrazones 2r2 ₃₄ , 4 ₁₅ 4 ₂ and hydrazides 5i,5 ₂ were tested in vitro against four different strains of P. falciparum. D10 and 3D7 are cloroquine-

sensitive (CQ-S) strains, while W2 and K1 are cloroquine-resistant (CQ-R) strains. The pharmacological results are displayed in tables 4. In this table the values for chloroquine (CQ) are also described.

The results show that almost all the tested compounds of Formula (I) exhibited a lower IC50 in cloroquine-resistant (CQ-R) strains than CQ itself. Moreover a lot of the tested compounds also showed a lower IC50 than CQ also on at least one of cloroquine-sensitive strains tested.

Table 4

Compd DIO(CQ-S) W2(CQ-R) 3D7(CQ-S) K1 (CQ-R) N° IC501SD IC501SD ED50 ED50 (nM) (nM) (nM) (nM)

2i 65.22± 4.68 23.73114.76 5.9 31.6

2 ₂ 196.58±73.11 86.93±6.19 61.5 270.1

2 ₃ 452.95±197.91 140.53±54.23 152.3 625.6

2 ₄ 174.29±17.77 248.59±79.69 48.9 384.9

2 ₅ 186.41162.19 258.461153.31 5.0 39.6

2 ₆ 340.81 ±66.35 163.96±54.06 227.0 581.5

2 ₇ 347.27±90.51 508.57±160.4 125.3 2128.0

2 ₈ 210.14±137.8 256.20±99.03 25.8 53.1

2i i 28.8515.97 58.29112.44 19.1 16.4

2i2 21.37115.91 18.9116.38 0.9 39.6

2i3 184.27±32.68 203.04±7.40 400.2 30.7

2i4 48.32111.09 57.6718.99 2.7 27.2

2i5 189.48±16.24 190.37±3.93 855.1 427.5

2i6 275.94±23.46 236.13±23.70 224.5 3528.2

220 122.56±5.06 281.82±106.48

2 ₂ 1 211.92±73.82 232.60±87.41 805.0 536.6

2 ₂ 6 99.44±24.69 128.39±57.71 65.1

2 ₂ 7 142.14±44.16 166.57±37.07 22.9 172.1

228 115.37±22.28 185.26±6.81 404.1 461.8

2 ₂ 9 142.14±44.16 166.57±37.07 22.9 172.1

230 131.61 ±35.49 184.08±17.64 507.4 149.2

2 ₃ 1 103.48110.21 150.09123.20 31.11 62.3

2 ₃ 5 144.97138.53 169.05159.58 31.8 63.7

4i 157.25165.15 37.72116.68 1.0 4.5

4 ₂ 96.8512.20 136.76120.53 0.38 4.49

CQ 39.33120.18 279.98186.95 10.1 257.6

In vivo activity of selected compounds

Compounds 2n and 2-ι ₂ were tested in vivo (single dose administration) against Plasmodium berghei (P.berghei) ANKA and CQ was used as reference drug. The results are shown in Table 5. All compounds were administered peros.

In vivo antimalarial activity was determined against the CQ-S strains (P.berghei) ANKA in CD1 mice according to a modified version of the 4-day suppressive test of Peters. Mice were inoculated with parasitized red blood cells. Thereafter, the drugs were administered to the animals once daily p.o. Drug treatments were initiated 24 h after parasite inoculation, for 4 consecutive days at the dose of 50 mg/Kg. Parasitemia levels were determined on the day following the last treatment.

These data show that the 70-80 % of parasetemia reduction is achieved by using 30 mg/kg dose of the claimed compounds. Even though the tested compounds are less potent than chloroquine, they are highly active in vitro against CQ-R strains (W2 and K1 ), as shown before.

Table 5