WO2002083641A2

WO2002083641A2 - Amino-aza-cyclohexanes for the treatment of malaria

Info

Publication number: WO2002083641A2
Application number: PCT/EP2002/003948
Authority: WO
Inventors: Christoph Boss; Christoph Binkert; Walter Fischli; Solange Meyer; Sylvia Richard-Bildstein; Panja Strickner; Thomas Weller
Original assignee: Actelion Pharmaceuticals Ltd
Current assignee: Actelion Pharmaceuticals Ltd
Priority date: 2001-04-17
Filing date: 2002-04-09
Publication date: 2002-10-24
Anticipated expiration: 2003-10-17
Also published as: AU2002304733A1; WO2002083641A3

Abstract

The invention relates to novel compounds which are substituted amino-aza-cyclohexane derivatives of the general formula I. The invention also concerns related aspects including pharmaceutical compositions containing one or more compounds of the general formula I and their use as medicaments for the treatment of protozoal infections, especially malaria.

Description

NOVEL AMINO-AZA-CYCLOHEXANES

The invention relates to novel compounds which are substituted amino-aza- cyclohexane derivatives of the general formula I. The invention also concerns related aspects including processes for the preparation of the compounds, pharmaceutical compositions containing one or more compounds of the general formula I and especially their use as medicaments to treat or prevent malaria infections or to treat or prevent other protozoal diseases like sleeping sickness, Chagas disease, amebiasis, giardiasis, trichomoniasis, toxoplasmosis, leishmaniasis etc.

Background of the invention:

Numerous serious diseases affecting humans as well as domestic and livestock animals are caused by protozoal organisms such as Kinetoplastida, Apicomplexa, Anaerobic protozoa, Microsporidia and Plasmodium, for example. The best known of these diseases is malaria. Malaria is one of the most serious and complex health problems affecting humanity in the 21^st century. The disease affects about 300 million people worldwide [2], killing 1 to 1.5 million people every year. Malaria is an infectious disease caused by four species of the protozoan parasite Plasmodium, P. falciparum being the most severe of the four. All attempts to develop vaccines against P. falciparum have failed so far. Therefore, therapies and preventive measures against malaria are confined to drugs. Various classes of antimalarial drugs exist. The most widely used are the quinoline derived compounds, e.g. chloroquine which has been an especially effective drug for both prophylaxis and therapy. However, resistance to many of the currently available antimalarial drugs is spreading rapidly, threatening people in areas where malaria is endemic, and new drugs are needed. Reports of multi-drug resistant strains of malaria parasites render the search for new antimalarial agents especially urgent. P. Falciparum enters the human body by way of bites of the female anophelino mosquito (it may also be transmitted by blood transfusion from asymptotic donors; almost all infected blood components including red cells, platelet concentrates, white cells, cryoprecipitates and fresh plasma can transmit malaria). The plasmodium parasite initially populates the liver, and during later stages of the infectious cycle reproduces in red blood cells. During this stage, the parasite degrades hemoglobin and uses the degradation products as nutrients for growth [1]. The limitations of the current antiprotozoal chemotherapeutic arsenal underscore the need for new drugs in this therapeutic area. The present invention relates to the identification of novel low molecular weight, non-peptidic, non-quinoline compounds which are able to kill the malaria parasite plasmodium falciparum to treat and/or prevent malaria.

The present invention provides an array of novel compounds. In preferred embodiements, these compounds may act as inhibitors of protozoal enzymes and are useful pharmaceutical agents for the treatment and prevention of protozoal infections. However, the mode of action could be unrelated to enzyme inhibition. For clarity and simplicity reasons, the following description is principally focused on compounds of the invention that inhibit enzymes relevant to the organism Plasmodium falciparum, the causative agent of malaria. This focus is intended to be illustrative and not limiting. Those skilled in the art will recognize a substantial structural homology and substrate specificity and activity overlap between the enzymes of P. Falciparum and other protozoa. Therefore, the compounds described in the invention are applicable for treatment or prevention of diseases caused by a variety of protozoa.

Plasmodium falciparum in vitro assay (³H-hypoxanthine incorporation):

Standard parasite strain: Plasmodium falciparum, K1 (chloroquine and pyrimethamine resistant).

Standard Drug: Artemisinine (Arteannum, Quinghaosu; Sigma 36,159-3) Standard Conditions:

Medium: RPMI 1640 without hypoxanthine supplemented with HEPES (5.94g/l), NaHCO₃ (2.1 g/l), Neomycin (100U/ml) + Albumax^R (5g/l), washed human red cells A+

Plates: Costar™ 96-well microtiter plates Incubation: 37°C; 4% CO₂, 3% O₂, 93% N₂.

Drug Preparation: For the assay, the compounds are diluted from the stock solution in DMSO. The highest concentration is 2 mM, followed by six dilution steps with a dilution factor of 3.

Assay Procedure: - prepare smears of the stocks of the plasmodium falciparum strains and determine the parasitaemia. The starting conditions for the assay are as follows: concentration of red cells: 2.5% (v/v) initial parasitaemia: 0.3%

1 μl of the compounds in DMSO is added to 200 μl of human red blood cells infected with parasite in complete medium. The compounds are tested in monoplicate and the concentration ranges from 10 μM to 10 nM. Six drugs can be tested this way on each plate. For each assay chloroquine and artemisinine are tested as the standards with 200 ng/ml as the highest concentration.

Compounds are tested in two independent assays and results are expressed in mean IC₅o values from the two experiments. Scheme 1 :

A1 - A8: positive control, red cells and parasites

A9 - A12: negative control, red cells only (no parasites)

B1 - H12: serial drug dilutions for 6 compounds in duplicate

- The plates are incubated in an incubation chamber at 37°C in a humidified atmosphere containing the special gas mixture. - After 48 hours 50μl ³H-hypoxanthine (=0.5 μCi) are added to each well of the plate. The plates are incubated for another 24 hours.

- Then the plates are harvested with a Betaplate™ cell harvester (Wallac, Zurich, Switzerland) which transfers the red blood cells onto a glass fiber filter and washes with distilled water. The dried filters are inserted into a plastic foil with 10 ml of scintillation fluid and counted in a BetaplateTM liquid scintillation counter (Wallace, Zurich, Switzerland)

- Data are transferred into a graphic programme (e.g. EXCEL), sigmoidal inhibition curves determined and IC50 values calculated. Table 1 : IC50 values (nM) for selected compounds:

References:

1. D. E. Goldberg, A. F.SIater, R.- Beavis, B. Chait, A. Cerami, G. B. Henderson, Hemoglobin degradation in the human malaria pathogen Plasmodium falciparum: a catabolic pathway initiated by a specific aspartic protease; J. Exp. Med., 1991 , 173, 961 - 969.

2. Gibbons et al.; Science, 256, 1135, 1992.

3. WO 01/14331 A2 (University of California, Berkley).

4. J. J. Edmunds et al., Ann. Rep. Med. Chem., 31 , 51 - 60, 1996. 5. K. Takahashi, Ed.; Aspartic Proteinases Structure, Function, Biology, and Biomedical Implications (Plenum Press, New York, 1995).

6. M. N. G. James, Ed.; Aspartic Proteinases, Retroviral and Cellular Enzymes (Plenum Press, New York, 1998)

7. J. Adams et al., Ann. Rep. Med. Chem., 31, 279 - 288 (1996). 8. J. March, Advanced Organic Chemistry, pp 918-919, and refs. cited therein; 4^thEd John Wiley & Sons, 1992.

9. A. Kubo, N. Saito, N. Kawakami, Y. Matsuyama, T. Miwa, Synthesis, 1987, 824-827.

10. R. K. Castellano, D. M. Rudkevich, J. Rebek, Jr., J. Am. Chem. Soc, 1996, 118, 10002-10003.

11. U. Schδllkopf, Pure Appl. Chem., 1983, 55, 1799-1806 and refs. cited therein; U. Schδllkopf, Top. Curr. Chem., 1983, 109, 65-84 and refs. cited therein; T. Wirth, Angew. Chem. Int. Ed. Engl., 1997, 36, 225-227 and refs. cited therein. 12. T. W. Greene, P. G. M. Wutts, Protective groups in organic synthesis; Wiley-lnterscience, 1991.

13. P. J. Kocienski, Protecting Groups, Thieme, 1994.

14. J. A. Radding, Development of Anti-Malarial Inhibitors of Hemoglobinases, Annual Reports in Medicinal Chemistry, 34, 1999, 159 - 168.

15. D. F. Wirth, Malaria: A Third World Disease in Need of First World Drug Development, Annual Reports in Medicinal Chemistry, 34, 1999, 349 - 358. The present invention relates to novel, low molecular weight organic compounds of the general formula I:

General Formula I

wherein

R¹ represents aryl; heteroaryl; aryl-lower alkyl; aryl-lower alkenyl; heteroaryl- lower alkyl; heteroaryl-lower alkenyl;

R² represents -SO₂-R³; -CO-R³; -CO-NH-R³; -(CH₂)_P-R³; or

-(CH₂)_P-CH(R⁴)₂ whereby R⁴ may be the same or different; -CO-N(R⁴)₂ whereby

R⁴ may be the same or different;

R³ represents aryl; aryl-lower alkyl; heteroaryl; heteroaryl-lower alkyl; lower alkyl;

R represents aryl; heteroaryl; cycloalkyl; lower alkyl;

p represents the whole numbers 0, , 2, 3, 4 or 5;

and optically pure enantiomers, mixtures of enantiomers such as for example racemates, optically pure diastereomers, mixtures of diastereomers, diastereomeric racemates, mixtures of diastereomeric racemates and the meso- form and pharmaceutically acceptable salts thereof. In the definitions of the general formula I - if not otherwise stated - the expression lower means straight and branched chain groups with one to seven carbon atoms, preferably 1 to 4 carbon atoms which may optionally be substituted with hydroxy or lower alkoxy. Examples of lower alkyl groups are methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert.-butyl, pentyl, hexyl, heptyl. Examples of lower alkoxy groups are methoxy, ethoxy, propoxy, iso-butoxy, sec.-butoxy and tert.-butoxy. Lower alkylendioxy-groups as substituents of aromatic rings onto two adjacent carbon atoms are preferably methylen-dioxy and ethylen-dioxy. Lower alkylen-oxy groups as substituents of aromatic rings onto two adjacent carbon atoms are preferably ethylen-oxy and propylen-oxy. Examples of lower alkanoyl-groups are acetyl, propanoyl and butanoyl. Lower alkenylen means e.g. vinylen, propenylen and butenylen.

The expression cycloalkyl, alone or in combination, means a saturated cyclic hydrocarbon ring system with 3 to 6 carbon atoms , e.g. cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl which may be substituted with lower alkyl groups.

The expression heterocyclyl, alone or in combination, means saturated or unsaturated (but not aromatic) five-, six- or seven-membered rings containing one or two heteroatoms chosen from nitrogen, oxygen or sulfur which may be the same or different and which rings may be substituted with lower alkyl, lower alkenyl, aryl, aryl-lower alkyloxy, aryl-oxy, amino, bis-(lower alkyl)-amino, alkanoyl-amino, halogen, nitro, hydroxy, lower alkoxy, phenoxy; examples of such rings are morpholinyl, piperazinyl, tetrahydropyranyl, dihydropyranyl, 1 ,4- dioxanyl, pyrrolidinyl, tetrahydrofuranyl, dihydropyrrolyl, imidazolidinyl, dihydropyrazolyl, pyrazolidinyl 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 five- membred aromatic rings containing one oxygen, one nitrogen or one sulfur atom; five membered aromatic rings containig 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, whereby such ring systems may be mono-, di- or tri- substituted with aryl, whereby the aryl-rings may again be substituted; aryloxy, aryl-lower alkyl-oxy, lower alkyl; lower alkenyl; lower alkyl-carbonyl; amino; lower alkyl-amino; bis-(lower-alkyl)-amino; lower alkanoyl-amino; ω-amino-lower alkyl; halogen; hydroxy; carboxyl; lower alkoxy; vinyloxy; allyloxy; ω-hydroxy-lower alkyl; nitro; cyano; amidino; trifluoromethyl; lower alkyl-sulfonyl.

The expression aryl, alone or in combination, means six membered aromatic rings and condensed systems like naphthyl or indenyl and the like whereby such ring systems may be mono-, di- or tri-substituted with aryl, whereby the aryl rings may again be substituted, aryloxy, aryl-lower alkyloxy, aryl-lower alkenyl, lower alkyl, lower alkenylen, lower alkyl-carbonyl, aryl-carbonyl, amino, lower alkyl- amino, aryl-amino, bis-(lower-alkyl)-amino, lower alkanoyl-amino, ω-amino-lower alkyl, halogen, hydroxy, carboxyl, lower alkoxy, vinyloxy, allyloxy, ω-hydroxy- lower alkyl, ω-hydroxy-lower alkoxy, nitro, cyano, amidino, trifluoromethyl, lower alkyl-sulfonyl, heteroaryl, whereby the heteroaryl rings may again be substituted.

It is understood that the substituents outlined relative to the expressions cycloalkyl, heterocyclyl, heteroaryl and aryl have been omitted in the definitions of the general formulae I to V and in claims 1 to 5 for clarity reasons but the definitions in formulae I to V and in claims 1 to 5 should be read as if they are included therein.

The expression pharmaceutically acceptable salts encompasses either salts with inorganic acids or organic acids like hydrochloric or hydrobromic acid; sulfuric acid, phosphoric acid, nitric acid, citric acid, formic acid, acetic acid, maleic acid, tartaric acid, methylsulfonic acid, p- toluolsulfonic acid and the like or in case the compound of formula I is acidic in nature with an inorganic base like an alkali or earth alkali base, e.g. sodium hydroxide, potassium hydroxide, calcium hydroxide and the like.

The compounds of the general formula I can contain one or more asymmetric carbon atoms and may be prepared in form of optically pure enantiomers, mixtures of enantiomers such as for example racemates, optically pure diastereomers, mixtures of diastereomers, diastereomeric racemates, mixtures of diastereomeric racemates and the meso-form.

The present invention encompasses all these forms. Mixtures may be separated in , a manner known per se, i.e. by column chromatography, thin layer chromatography, HPLC, crystallization etc.

The compounds of the general formula I and their pharmaceutically acceptable salts may be used as therapeutics e.g. in form of pharmaceutical compositions. They may especially be used to in prevention or treatment of malaria. These compositions may be administered in enteral or oral form e.g. as tablets, dragees, gelatine capsules, emulsions, solutions or suspensions, in nasal form like sprays or rectally in form of suppositories. These compounds may also be administered in intramuscular, parenteral or intraveneous form, e.g. in form of injectable solutions.

These pharmaceutical compositions may contain the compounds of formula I as well as their pharmaceutically acceptable salts in combination with inorganic and/or organic excipients which are usual in the pharmaceutical industry like lactose, maize or derivatives thereof, talcum, stearinic acid or salts of these materials.

For gelatine capsules vegetable oils, waxes, fats, liquid or half-liquid polyols etc. may be used. For the preparation of solutions and sirups e.g. water, polyols saccharose, glucose etc. are used. Injectables are prepared by using e.g. water, polyols, alcohols, glycerin, vegetable oils, lecithin, liposomes and the like. Suppositories are prepared by using natural or hydrogenated oils, waxes, fatty acids (fats), liquid or half-liquid polyols and the like.

The compositions may contain in addition preservatives, stability improving substances, viscosity improving or regulating substances, solubility improving substances, sweeteners, dyes, taste improving compounds, salts to change the osmotic pressure, buffer, anti-oxidants and the like.

The compounds of formula I may also be used in combination with one or more other therapeutically useful substances e. g. with other antimalarials like quinolines (quinine, chloroquine, amodiaquine, mefloquine, primaquine, tafenoquine), peroxide antimalarials (artemisinin, artemether, artesunate), pyrimethamine-sulfadoxine antimalarials (e.g. Fansidar), hydroxynaphtoquinones (e.g. atovaquone), acroline-type antimalarials (e. g. pyronaridine) and other antiprotozoal agents like ethylstibamine, hydroxystilbamidine, pentamidine, stilbamidine, quinapyramine, puromycine, propamidine, nifurtimox, melarsoprol, nimorazole, nifuroxime, aminitrozole and the like.

The dosage may vary within wide limits but should be adapted to the specific situation. In general the dosage given in oral form should daily be between about 3 mg and about 3 g, peferably between about 10 mg and about 1 g, especially preferred between 5 mg and 300 mg, per adult with a body weight of about 70 kg. The dosage should be administered preferably in 1 to 3 doses per day which are of equal weight. As usual, children should receive lower doses which are adapted to body weight and age.

Preferred compounds are compounds of the formula II

wherein R¹ is as defined in general formula I above

and optically pure enantiomers, mixtures of enantiomers such as for example racemates, optically pure diastereomers, mixtures of diastereomers, diastereomeric racemates, mixtures of diastereomeric racemates and the meso- form and pharmaceutically acceptable salts thereof.

Also preferred compounds are compounds of formula III

Formula III wherein

R⁵ represents aryl; heteroaryl; cycloalkyl;

and optically pure enantiomers, mixtures of enantiomers such as for example racemates, optically pure diastereomers, mixtures of diastereomers, diastereomeric racemates, mixtures of diastereomeric racemates and the meso- form and pharmaceutically acceptable salts thereof. Also preferred compounds are compounds of the formula IV

Formula IV

Also preferred compounds are compounds of the formula V

heteroaryl

Formula V

and optically pure enantiomers, mixtures of enantiomers such as for example racemates, optically pure diastereomers, mixtures of diastereomers, diastereomeric racemates, mixtures of diastereomeric racemates and the meso- form and pharmaceutically acceptable salts thereof. Especially preferred compounds are those depicted in Table 2:

Table 2:

The compounds of the general formula I of the present invention may be prepared according to the general sequences of reactions outlined below, wherein R¹, R², R³, R⁴ and p are as defined in general formula I above (for simplicity and clarity reasons, only parts of the synthetic possibilities which lead to compounds of formulae I to V are described). For general methods of certain steps see also pages 15 - 19 and 20 - 34. Scheme 2: Preparation of substituted 4-amino-N-benzyl-piperidines:

1

Typical procedure for the reductive amination (Synthesis of compounds 2):

The amine (1) and the aldehyde {R¹-CHO} (1.5 eq.) are mixed in anhydrous methanol and stirred for 6 h. The mixture is then treated with sodium borohydride (1.5 eq.) and stirred for 2 h. Purified Amberlyst 15 or another suitable scavenger is added and the suspension is shaken for 12 h. The resin is then separated by filtration and washed with methanol. The secondary amine 2 is removed from the resin by adding a 2 M methanolic ammonia solution. The resin is drained after 30 min and washed with methanol. The filtrate is evaporated to yield the pure secondary amine 2.

The N-Boc protected 4-amino-piperidine 3 can be prepared in a two step procedure starting by reacting 4-hydroxy-N-Boc-piperidine, with methanesulfonylchloride in an inert solvent like DCM in the presence of a base like TEA to generate 4-mesyloxy-N-Boc-piperidine. The mesyloxy group is substituted with sodium azide followed by reduction of the azide functionality to the amino group to give 3. In accordance to this procedure, the N-Boc protected 3-amino-piperidine 4 can also be prepared in the same way. Scheme 3: Synthesis of N-Boc-4-aminopiperidine (3) and N-Boc-3- aminopiperidine (4):

3

a) Methanesulfonylchloride, CH₂CI₂, NEt₃, Rt, 12 h; b) Sodium azide, DMF, 70°C, 6 - 8 h; c) Ethylacetate, Pd/C (10%), H₂, rflx, 12 h.

Scheme 4: Preparation of substituted 4-amino-N-(lower alkyl-aryl)-piperidines:

13

The amine 3 is transformed to the secondary amine 5 via the typical procedure for the reductive amination described above. Subsequent protection with the Cbz-group to 6 is achieved via typical procedures described in the literature [12- 13]. Boc-deprotection is achieved either with hydrochloric acid in a solvent like diethylether or dioxane or with TFA in DCM. The second reductive amination step of the intermediate 7 to the compounds 8 again can be performed according to the typical procedure described above. Compound 7 can also be transformed with acylating reagents like isocyanates, acid chlorides or sulfonyl chlorides to yield products with an urea-, amide- (12) or sulfonamide (10) functionality instead of the amine functionality at the ring nitrogen atom. Removal of the Cbz-group to form the secondary exocyclic amino functionality (final compounds 9, 11 and 13) is performed according to typical procedures described in the literature [12-13].

Compounds based on the 3-amino-piperidine template (see Scheme 3) can be prepared by using 3-amino-N-Boc-piperidine as starting material. All other chemical transformations can be performed as described above in scheme 4.

An equally suitable method for the preparation of compounds according to general fromula I is depicted in scheme 5 below:

Scheme 5:

Scheme 5 only shows parts of the synthetic possibilities available, starting from piperidine-4-on (14). All chemical transformations can be performed according to procedures published in the literature.

In general, all chemical transformations can be performed according to well known standard methodologies as described in the literature or as described in the typical procedure above.

The following examples illustrate the invention but do not limit the scope thereof. All temperatures are stated in °C.

List of abbreviations:

Boc or boc tert.-butyloxycarbonyl

Cbz benzyloxycarbonyl

DBU 1 ,8-diazabicyclo[5.4.0]undec-7-ene(1 ,5-5)

DCM dichloromethane

DMF dimethylformamide

DMSO dimethylsulfoxide

EtOAc ethyl acetate

TEA triethylamine

TFA trifluoroacetic acid

THF tetrahydrofuran

General Procedures and Examples:

The following compounds were prepared according to the procedures described for the synthesis of compounds encompassed by the general formulae hereinbefore. All compounds were characterized by ¹ H-NMR (300MHz) and occasionally by ¹³C-NMR (75MHz) (Varian Oxford, 300MHz; chemical shifts are given in ppm relative to the solvent used; multiplicities: s = singlet, d = doublet, t = triplet; m = multiplet), by LC-MS (Waters Micromass; ZMD-platform with ESI- probe with Alliance 2790 HT; Colum: 2x30mm, Gromsil ODS4, 3μm, 120A; Gradient: 0 - 100% acetonitril in water, 6 min, with 0.05% formic acid, flow: 0.45ml/min; t_r is given in minutes.), by TLC (TLC-plates from Merck, Silica gel 60 F₂5₄) and occasionally by melting point.

a) General Procedure:

Typical procedure A) for the reductive amination:

The amine and the aldehyde (1.5 eq.) (which are used as starting materials, are known compounds or the synthesis is described in the relative example), are mixed in anhydrous methanol and stirred for 6 h. The mixture is then treated with sodium borohydride (1.5 eq.) and stirred for 2 h. Purified Amberlyst 15 or another suitable scavenger is added and the suspension is shaken for 12 h. The resin is then separated by filtration and washed with methanol. The secondary amine is removed from the resin by adding a 2 M methanolic ammonia solution. The resin is drained after 30 min and washed with methanol. The filtrate is evaporated to yield the pure secondary amine. Typical procedure B) for the acylation:

To a solution of the amine in anhydrous ethyl acetate is added vacuum dried Amberlyst 21 or another suitable scavenger followed by the addition of the carboxylic acid chloride (1.5 eq.). After shaking the suspension for 2 h, an aliquot of water is added in order to hydrolyze the excess of the carboxylic acid chloride and shaking is continued for 1 h. The resin is then removed by filtration, washed with EtOAc and the solution is evaporated to yield the pure amide.

Typical Procedure C for the reductive amination of a ketone:

The amine hydrochloride (1 eq) is dissolved in DCM (6 ml / mmol) and TEA (1 eq) is added, followed by the addition of the ketone (1.5 eq) and sodium triacetoxy borohydride (1.5 eq) and acetic acid (1 eq). The mixture is stirred for 12 h. Amberlyst 15 is added and the mixture is shaken for 2 h followed by filtration. The resin is washed with methanol and the solvents are evaporated.

b) Examples:

Example 1 :

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 2'-chloro-biphenyl-4-carbaldehyde to give (1-benzyl- piperidin-4-yl)-(2'-chloro-biphenyl-4-ylmethyl)-amine. LC-MS: t_R = 3.00; ES+: 391.24.

Example 2:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 4'-fluoro-biphenyl-4-carbaldehyde to give (1-benzyl- piperidin-4-yl)-(4'-fluoro-biphenyl-4-ylmethyl)-amine. LC-MS: t_R = 2.89; ES+: 375.23.

Example 3:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 3,4-dibenzyloxy-benzaldehyde to give (1-benzyl- piperidin-4-yl)-(3,4-bis-benzyloxy-benzyl)-amine. LC-MS: t_R = 3.44; ES+: 493.52.

Example 4:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 2-hydroxy-4-benzyloxy-benzaldehyde to give 5- benzyloxy-2-[(1-benzyl-piperidin-4-ylamino)-methyl]-phenol. LC-MS: t_R = 2.80; ES+: 403.24.

Example 5:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 4-Pyrimidin-5-yl-benzaldehyde to give (1-benzyl- piperidin-4-yl)-(4-pyrimidin-5-yl-benzyl)-amine. LC-MS: t_R = 2.34; ES+: 359.27.

Example 6:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 3-methoxy-4-benzyloxy-benzaidehyde to give (4- benzyloxy-3-methoxy-benzyl)-(1-benzyl-piperidin-4-yl)-amine. LC-MS: t_R = 2.81; ES+: 417.40.

Example 7:

According to typical procedure C), commercially available 1-benzyl-piperidin-4- one, is reacted with 2-(3,4-bis-benzyloxy-phenyl)-ethylamine to give (1-benzyl- piperidin-4-yl)-[2-(3,4-bis-benzyloxy-phenyI)-ethyl]-amine. LC-MS: t_R = 3.44; ES+: 507.42.

Example 8:

According to typical procedure A), commercially available 1 -benzyl-piperidin-4- ylamine, is reacted with 4'-formyl-biphenyl-4-carbonitrile to give 4'-[(1-benzyl- piperidin-4-ylamino)-methyl]-biphenyl-4-carbonitrile. LC-MS: t_R = 2.82; ES+: 382.32.

Example 9:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 4-styryl-benzaldehyde to give (1-benzyl-piperidin-4-yl)- (4-styryl-benzyl)-amine. LC-MS: t_R = 3.13; ES+: 453.36.

Example 10:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 2-pentyl-3-phenyl-propenal to give (1-benzyl-piperidin-4- yl)-(2-pentyl-3-phenyl-allyl)-amine. LC-MS: t_R = 3.17; ES+: 377.48.

Example 11 :

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 3-phenyl-propionaldehyde to give (1-benzyl-piperidin-4- yl)-(3-phenyl-propyl)-amine. LC-MS: t_R = 2.34; ES+: 309.35.

Example 12:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 3-benzyloxy-4-methoxy-benzaldehyde to give (3- benzyloxy-4-methoxy-benzyl)-(1-benzyl-piperidin-4-yl)-amine. LC-MS: t = 2.72; ES+: 417.39.

Example 13:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 4-benzyloxy-benzaldehyde to give (4-benzyloxy-benzyl)- (1-benzyl-piperidin-4-yl)-amine. LC-MS: t_R = 2.73; ES+: 387.41.

Example 14:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with biphenyl-3-carbaldehyde to give (1-benzyl-piperidin-4- yl)-biphenyl-3-ylmethyl-amine. LC-MS: t_R = 2.81; ES+: 357.19.

Example 15:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 3-(4-chloro-phenoxy)-benzaldehyde to give (1-benzyl- piperidin-4-yl)-[3-(4-chloro-phenoxy)-benzyl]-amine. LC-MS: t_R = 2.86; ES+: 407.37.

Example 16:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 4'-dimethylamino-biphenyl-4-carbaldehyde to give (1- benzyl-piperidin-4-yl)-(4'-dimethylamino-biphenyl-4-ylmethyl)-amine. LC-MS: t_R = 2.61 ; ES+: 400.30.

Example 17:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 2'-fluoro-biphenyl-4-carbaldehyde to give (1-benzyl- piperidin-4-yl)-(2'-fluoro-biphenyl-4-ylmethyl)-amine. LC-MS: t_R = 2.88; ES+: 375.29.

Example 18:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 4-pyridin-2-yl-benzaldehyde to give (1-benzyl-piperidin- 4-yl)-(4-pyridin-2-yl-benzyl)-amine. LC-MS: t_R = 2.35; ES+: 358.29.

Example 19:

According to typical procedure A), commercially available 1-benzyl-piperidin-4- ylamine, is reacted with 4-dibutylamino-benzaldehyde to give (1-benzyl-piperidin- 4-yl)-(4-dibutylamino-benzyl)-amine. LC-MS: t_R = 2.96; ES+: 408.53.

Non-commercially available biphenylaldehyde derivatives could be prepared according to the procedure described below:

Typical procedure D) for the Suzuki coupling:

To a solution of an aryl bromide in toluene is added the boronic acid derivative (1.1 eq.) in isopropanol and a 2M aqueous solution of potassium carbonate (5 eq.). The mixture is purged with nitrogen for 10 min and tetrakis(triphenylphosphine) palladium (0.03 eq.) is added. After heating under reflux for 6 h, water is added to the cooled reaction mixture and the product is extracted with EtOAc. The organic phase is washed with brine and dried over sodium sulfate. The solvent is evaporated to give the crude aldehyde, which is purified by flash chromatography (EtOAc/heptane gradient).

Referential Example 1 :

According to typical procedure D), 4-formyibenzeneboronic acid is coupled with 2-(4-bromophenoxy) ethanol to give

4'-(2-Hydroxy-ethoxy)-biphenyl-4-carbaldehyde

Referential Example 2:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 1 -bromo-2-fluorobenzene to give

2'-Fluoro-biphenyl-4-carbaldehyde

Referential Example 3:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 3-bromobenzotrifluoride to give

3'-Trifluoromethyl-biphenyl-4-carbaldehyde

Referential Example 4:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 1-bromo-2-chlorobenzene o give

2'-Chloro-biphenyl-4-carbaldehyde Referential Example 5:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 5-bromopyrimidine to give

4-Pyrimidin-5-yl-benzaldehyde

Referential Example 6:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 1-bromo-3-(trifluoromethoxy)benzene to give

3'-Trifluoromethoxy-biphenyl-4-carbaldehyde

Referential Example 7:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 1-bromo-4-fluorobenzene to give

4'-fluoro-biphenyl-4-carbaldehyde Referential Example 8:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 4-bromo-benzonitrile to give

4'-formyl-biphenyl-4-carbonitrile

Referential Example 9:

According to typical procedure D), 3-formylbenzeneboronic acid is coupled with 4-bromo-benzene to give

Biphenyl-3-carbaldehyde

Referential Example 10:

According to typical procedure D), 4-formylbenzeneboronic acid is coupled with 4-bromo-N,N-dimethylaminobenzene to give

4'-dimethylamino-biphenyl-4-carbaldehyde

Claims

Claims:

1. Compounds of the general formula I

HN- 1

General Formula I

wherein

R² represents -SO₂-R³; -CO-R³; -CO-NH-R³; -(CH₂)_P-R³; or

R⁴ may be the same or different;

R represents aryl; aryl-lower alkyl; heteroaryl; heteroaryl-lower alkyl; lower alkyl;

R >4 represents aryl; heteroaryl; cycloalkyl; lower alkyl;

p represents the whole numbers 0, 1 , 2, 3, 4 or 5;

2. Compounds of formula II

Formula II wherein

R¹ is as defined in general formula I above

3. Compounds of formula III

Formula III

wherein

R⁵ represents aryl; heteroaryl; cycloalkyl; and optically pure enantiomers, mixtures of enantiomers such as for example racemates, optically pure diastereomers, mixtures of diastereomers, diastereomeric racemates, mixtures of diastereomeric racemates and the meso- form and pharmaceutically acceptable salts thereof.

4. Compounds of formula IV

Formula IV

5. Compounds of formula V

Formula V

6. A compound according to any one of the claims 1 to 5, having a structure selected from the group consisting of:

7. A compound as described as end-product in any of the examples 1 to 19.

8. Pharmaceutical compositions containing one or more compounds as claimed in any one of claims 1 to 7 and inert excipients.

9. Pharmaceutical compositions according to claim 8 for treatment or prevention of diseases demanding the inhibition of protozoal enzymes like serine-, cysteine- or aspartyl- or metalloproteases or digestive enzymes and combinations thereof.

10. Pharmaceutical compositions according to claim 8 for treatment or prevention of diseases demanding the interruption of the reproductive cycle of a protozoa.

11. Pharmaceutical compositions according to claim 8 for treatment or prevention of malaria.

12. Pharmaceutical compositions according to claim 8 for treatment or prevention of protozoal infections.

13. Pharmaceutical compositions according to claim 8, which contain aside of one or more compounds of the general formula I at least one known HIV protease inhibitor or at least one known HIV reverse transcriptase inhibitor or at least one known antimalarial agent or at least one known antiprotozoal agent or at least one known cathepsin D or E inhibitor or combinations thereof.

14. A process for the preparation of a pharmaceutical composition according to any one of claims 8 to 13, characterized by mixing one or more active ingredients according to any one of claims 1 to 7 with inert excipients in a manner known per se.

15. Use of at least one of the compounds of the general formula I for the treatment or prevention of diseases by administering the compound in a suitable method and formulation and in a therapeutically effective dose to cure protozoal infections.