Alpha-amino-acid compounds

Dipeptidyl peptidase IV is a membrane serine protease that is present in many human tissues and involved in numerous pathologies.

In particular, it has been shown that DPP IV is responsible for the inactivation of GLP-1 (glucagon-like peptide-1). GLP-1 is an important stimulator of the secretion of insulin in the pancreas and accordingly has a direct beneficial effect on the level of glucose in the blood.

Inhibition of DPP IV accordingly constitutes an extremely promising approach in the treatment of glucose intolerance and of disorders associated with hyperglycaemia, such as, for example, non-insulin-dependent diabetes (type II diabetes) or obesity.

DPP IV inhibitors have already been described in the literature, for example amide compounds in Patent Application EP 0 490 379 and in the journal Adv. Exp. Med. Biol. 1997, 421, 157-160, and carbamate compounds in Patent Application DE 19826972.

Moreover, α-amino acid compounds, analogues of arginine, have been described in Patent Application WO 96/27593 as inhibitors of NO-synthase, for use, as such, in the treatment of pathologies of the central and peripheral nervous systems, pathologies of dysfunctions of the gastrointestinal and urinary systems, and pathologies associated with the cardiovascular or bronchopulmonary system.

The compounds of the invention have dipeptidyl peptidase IV-inhibiting properties, which thus makes them especially useful in the treatment of glucose intolerance and disorders associated with hyperglycaemia.

More especially, the present invention relates to compounds of formula (I):

wherein:

represents a 5-membered nitrogen-containing heterocycle optionally substituted by a cyano group,

Ak represents a linear or branched (C 1 -C 6 )alkylene chain,

X represents a single bond or a phenylene group,

R 1 and R 2 , which may be identical or different, each represent a hydrogen atom or a linear or branched (C 1 -C 6 )alkyl group,

Y represents NR 4 or CH—NO 2 ,

R 4 represents a hydrogen atom or a linear or branched (C 1 -C 6 )alkyl group,

R 3 represents:

a group selected from linear or branched (C 1 -C 6 )alkyl, nitro and cyano, when Y represents CH—NO 2 , or

a group selected from nitro and cyano, when Y represents NR 4 ,

their tautomers when they exist, their optical isomers, and addition salts thereof with a pharmaceutically acceptable acid,

with the exclusion of compounds wherein, simultaneously,

represents an unsubstituted 5-membered nitrogen-containing heterocycle, Ak represents the group —(CH 2 ) 3 —, X represents a single bond, Y represents NH and R 3 represents the nitro group.

Among the pharmaceutically acceptable acids, there may be mentioned by way of non-limiting example hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, acetic acid, trifluoroacetic acid, lactic acid, pyruvic acid, malonic acid, succinic acid, glutaric acid, fumaric acid, tartaric acid, maleic acid, citric acid, ascorbic acid, methanesulphonic acid, camphoric acid, oxalic acid, etc.

“5-membered nitrogen-containing heterocycle” is understood to mean a 5-membered saturated monocyclic group containing one, two or three hetero atoms, one of which hetero atoms is the nitrogen atom, and any additional hetero atoms present are selected from the atoms oxygen, nitrogen and sulphur.

The preferred 5-membered nitrogen-containing heterocycles are the groups pyrrolidinyl and thiazolidinyl.

The compounds of formula (I) wherein R 2 represents a hydrogen atom exist in two tautomeric forms represented by the formulae (Ia) and (Ib):

which both form an integral part of the invention.

The compounds of formula (I) wherein R 3 represents a hydrogen atom exist in two tautomeric forms represented by the formulae (Ic) and (Id):

which both form an integral part of the invention.

The preferred compounds of formula (I) are those wherein

represents a 1-pyrrolidinyl group optionally substituted by a cyano group, or a 1,3-thiazolidin-3-yl group optionally substituted by a cyano group.

The preferred compounds of formula (I) are those wherein the configuration α to the amide function is (S).

An advantageous aspect of the invention relates to compounds of formula (I) wherein Ak represents the group (CH 2 ) 4 .

Another advantageous aspect of the invention relates to compounds of formula (I) wherein

represents a 1-pyrrolidinyl group substituted by a cyano group, or a 1,3-thiazolidin-3-yl group substituted by a cyano group, and Ak represents the group (CH 2 ) 3 .

A further advantageous aspect of the invention relates to compounds of formula (I) wherein X represents a single bond.

A further advantageous aspect of the invention relates to compounds of formula (I) wherein Y represents a group NR 4 , wherein R 4 represents a hydrogen atom or a linear or branched (C 1 -C 6 )alkyl group.

A further advantageous aspect of the invention relates to compounds of formula (I) wherein R 3 represents the nitro group.

Among the preferred compounds of the invention, there may be mentioned more especially:

N-{(4S)-4-amino-5-[(2S)-2-cyano-1-pyrrolidinyl]-5-oxopentyl}-N′-nitroguanidine, its tautomers, optical isomers, and addition salts thereof with a pharmaceutically acceptable acid,

N-{(5S)-5-amino-6-[(2S)-2-cyano-1-pyrrolidinyl]-6-oxohexyl}-N′-nitroguanidine, its tautomers, optical isomers, and addition salts thereof with a pharmaceutically acceptable acid, and

N-{(5S)-5-amino-6-(1,3-thiazolidin-3-yl)-6-oxohexyl}-N′-nitroguanidine, its tautomers, optical isomers, and addition salts thereof with a pharmaceutically acceptable acid.

The invention relates also to a process for the preparation of compounds of formula (I), characterised in that a compound of formula (II):

wherein Ak and X are as defined for formula (I), P 1 represents an amino-function-protecting group, and P 2 represents an amino-function-protecting group other than P 1 ,

is reacted with a compound of formula (III):

wherein

is as defined for formula (I),

under conventional peptide coupling conditions, to yield, after deprotection, a compound of formula (IV),

wherein

P 1 , Ak and X are as defined hereinbefore,

which is then converted, by conventional organic chemistry reactions, followed by a deprotection reaction, to a compound of formula (I),

which is purified, if necessary, according to a conventional purification technique, separated, if desired, into its optical isomers according to a conventional separation technique, and converted, if desired, into addition salts thereof with a pharmaceutically acceptable acid.

The compounds of formula (Ie), a particular case of the compounds of formula (I):

wherein

R 1 , Ak and X are as defined for formula (I), can also be obtained starting from the compound of formula (V):

wherein P 1 , Ak and X are as defined hereinbefore, which is reacted with a compound of formula (III), under conventional peptide coupling conditions,

to yield, after deprotection where necessary, a compound of formula (Ie), which is purified, if necessary, according to a conventional purification technique, separated, if desired, into its optical isomers according to a conventional separation technique, and converted, if desired, into addition salts thereof with a pharmaceutically acceptable acid.

The compounds of the present invention, in addition to being new, have pharmacologically valuable properties. They have dipeptidyl peptidase IV-inhibiting properties which make them useful in the treatment of glucose intolerance and of disorders associated with hyperglycaemia, such as type II diabetes or obesity.

The invention relates also to pharmaceutical compositions comprising as active ingredient at least one compound of formula (I) with one or more suitable inert, non-toxic excipients. Among the pharmaceutical compositions according to the invention, there may be mentioned more especially those that are suitable for oral, parenteral (intravenous, intramuscular or subcutaneous) or nasal administration, tablets or dragées, sublingual tablets, gelatin capsules, lozenges, suppositories, injectable preparations, drinkable suspensions, etc.

The useful dosage can be adapted according to the nature and severity of the disorder, the route of administration and the age and weight of the patient and any associated treatments. The dosage varies from 0.5 mg to 2 g per 24 hours in one or more administrations.

The following Examples illustrate the invention and do not limit it in any way.

The starting materials used are known products or are prepared according to known procedures.

The structures of the compounds described in the Examples were determined according to the usual spectrometric techniques (infrared, NMR, mass spectrometry).

The expression “compound of configuration (2α) or (2β)” is understood to mean a compound selected from the compounds of absolute configurations (2R) and (2S), it being understood that when compound (2α) represents the compound of absolute configuration (2R), then compound (2β) represents the compound (2S).

N-{(4S)-4-Amino5-[(2S)-2-cyano-1-pyrrolidinyl]-5-oxopentyl}-N′-nitroguanidine Hydrochloride

Step A: N-{(4S)-4-[(Tert-butyloxycarbonyl)-amino]-5-[(2S)-2-cyano-1-pyrrolidinyl]-5-oxopentyl}-N′-nitroguanidine

10 mmol of(2S)-2-cyano-pyrrolidine, 10 mmol of 1-hydroxybenzotriazole and 10 mmol of dicyclohexylcarbodiimide are added to 10 mmol of N 2 -(tert-butyloxycarbonyl)-N 5 -[(imino)-(nitroamino)-methyl]-ornithine dissolved in dimethylformamide. After stirring overnight at room temperature, the dicyclohexylurea that has formed is filtered off and then the dimethylformamide is removed by evaporation. The resulting residue is purified by chromatography over silica (eluant: dichloromethane/ethanol 95/5) to yield the expected product.

A 4N solution of hydrochloric acid in dioxane is added to 10 mmol of the compound obtained in the preceding Step dissolved in dioxane. After stirring for 24 hours at room temperature, the solvent is removed by evaporation, water is added and the solution is lyophilised to yield the expected product.

N-[(4S)-4-Amino-5-(1-pyrrolidinyl)-5-oxopentyl]-N′-cyanoguanidine sesquihydrochloride

The expected product is obtained according to the process described in Step A of Example 1 starting from (S)-N 5 -(benzyloxycarbonyl)-N 2 -(tert-butyloxycarbonyl)-ornithine and pyrrolidine.

10 mmol of the compound obtained in the preceding Step dissolved in ethanol are hydrogenated in the presence of 10% palladium-on-carbon, at room temperature and ambient pressure, for 6 hours. The reaction mixture is then filtered and evaporated and then, after the addition of water, lyophilised to yield the expected product.

The expected product is obtained according to the process described in Synthesis 1975, 332, starting from the compound obtained in the preceding Step and NaN(CN) 2 .

The expected product is obtained according to the process described in Step B of Example 1 starting from the compound obtained in the preceding Step.

N-[(4S)-4-Amino-5-(1,3-thiazolidin-3-yl)-5oxopentyl]-N′-cyanoguanidine

Step A: 3-{(S)-N 5 -(Tert-butyloxycarbonyl)-N 2 -[(9H-fluoren-9-yl-methoxy)-carbonyl]-ornithyl}-1,3-thiazolidine

The expected product is obtained in accordance with the process described in Step A of Example 1 starting from (S)-N 5 -(tert-butyloxycarbonyl)-N 2 -(9H-fluoren-9-yl-methoxy)-carbonyl]-ornithine and 1,3-thiazolidine.

The expected product is obtained according to the process described in Step B of Example 1 starting from the compound obtained in the preceding Step.

The expected product is obtained according to the process described in Synthesis 1975, 332, starting from the compound obtained in the preceding Step and NaN(CN) 2 .

N-[(5S)-5-Amino-6-(1-pyrrolidinyl)-6-oxohexyl]-N′-cyanoguanidine hydrochloride

The expected product is obtained according to the process described in Example 2, replacing (S)-N 5 -(benzyloxycarbonyl)-N 2 -(tert-butyloxycarbonyl)-ornithine by (S)-N 6 -(benzyloxy-carbonyl)-N 2 -(tert-butyloxycarbonyl)-lysine.

N 1 -[(4S)-4-Amino-5-(1-pyrrolidinyl)-5-oxopentyl]-N 2 -methyl-2-nitro-1,1-ethylenediamine dihydrochloride

The expected product is obtained according to the process described in Step A of Example 1 starting from (S)-N 5 -(benzyloxycarbonyl)-N 2 -(tert-butyloxycarbonyl)-ornithine and pyrrolidine.

10 mmol of the compound obtained in the preceding Step dissolved in ethanol are hydrogenated in the presence of 10% palladium-on-carbon, at room temperature and ambient pressure, for 6 hours. The reaction mixture is then filtered and evaporated and then, after the addition of water, lyophilised to yield the expected product.

Step C: N 1 -{(4S)-4-[(Tert-butyloxycarbonyl)-amino]-5-(1-pyrrolidinyl)-5-oxopentyl}-N 2 -methyl-2-nitro-1,1-ethylenediamine

The expected product is obtained according to the process described in Bioorg. Med. Chem. 1997, 7 (23), 3045-3048, starting from the compound obtained in the preceding Step and N-methyl-1-methylthio-2-nitro-ethyleneamine.

Step D: N1-[(4S)-4-Amino-5-(1-pyrrolidinyl)-5-oxopentyl]-N2-methyl-2-nitro-1,1-ethylenediamine dihydrochloride

The expected product is obtained according to the process described in Step B of Example 1 starting from the compound obtained in the preceding Step.

N-[(4S)-4-Amino-5-(1-pyrrolidinyl)-5-oxopentyl]-N″-cyano-N′-methylguanidine hydrochloride

The expected product is obtained according to the process described in Step A of Example 1, starting from (S)-N 5 -(benzyloxycarbonyl)-N 2 -(tert-butyloxycarbonyl)-omithine and pyrrolidine.

10 mmol of the compound obtained in the preceding Step dissolved in ethanol are hydrogenated in the presence of 10% palladium-on-carbon, at room temperature and ambient pressure, for 6 hours. The reaction mixture is then filtered and evaporated and then, after the addition of water, lyophilised to yield the expected product.

Step C: N-{(4S)-4-[(Tert-butyloxycarbonyl)-amino]-5-(1-pyrrolidinyl)-5-oxopentyl}-N″-cyano-N′-methylguanidine

The expected product is obtained according to the process described in Chem. Pharm. Bull. 1997, 45 (1), 53-61, starting from the compound obtained in the preceding Step, N-cyanoimido-S,S-dimethyldithiocarbonate and methylamine.

The expected product is obtained according to the process described in Step B of Example 1, starting from the compound obtained in the preceding Step.

Mass spectrometry: [M+H]+=267; [M+Cl]+=301; [M−H]−=265.

The expected product is obtained according to the process described in Step A of Example 1, starting from (2S)-2-[(tert-butyloxycarbonyl)-amino]-3-(4-aminophenyl)-propanoic acid and pyrrolidine.

Step B: N-{4-[(2S)-2-[(Tert-butyloxycarbonyl)-amino]-3-oxo-3-(1-pyrrolidinyl)-propyl]-phenyl}-N′-nitroguanidine

The expected product is obtained by reacting the compound obtained in the preceding Step with N-methyl-N′-2-dioxohydrazinecarboximidohydrazide-2-oxide, according to the process described in J. Am. Chem. Soc. 1949, 71, 1968-1970.

The expected product is obtained according to the process described in Step B of Example 1, starting from the compound obtained in the preceding Step B.

In vitro Inhibition of Dipeptidyl Peptidase IV

The effect of the compounds on the in vitro enzymatic activity of DPPIV is evaluated as follows. The enzyme, from pig kidney, is assayed using a chromogenic substrate, glycyl-prolyl-p-nitroanilide 1.4 mM, which is hydrolysed to release p-nitroaniline, which absorbs at 405 nm. The activity of the enzyme is determined by absorbance, in the presence of variable concentrations of the compound being evaluated (mostly from 10 −4 to 10 −9 M). The data obtained allow the effective dose for 50% inhibition of the control activity (IC 50 ) to be determined. The compounds of the invention have an IC 50 of from 1 nM to 10 μM.

Pharmaceutical Composition