AU2002334229A1

AU2002334229A1 - Novel dipeptidyl peptidase IV (DP-IV) inhibitors as anti-diabetic agents

Info

Publication number: AU2002334229A1
Application number: AU2002334229A
Authority: AU
Inventors: David Michael Evans; Andre Tartar
Original assignee: Ferring BV
Current assignee: Ferring BV
Priority date: 2001-10-23
Filing date: 2002-10-23
Publication date: 2003-05-06

Description

NOVEL DIPEPTIDYL PEPTIDASE IV (DP-IV) INHIBITORS AS ANTI-DIABETIC AGENTS

The present invention relates to novel compounds that are prodrugs of inhibitors of dipeptidyl peptidase IV. The compounds are useful in the treatment of, inter alia, type 2 diabetes and impaired glucose tolerance.

BACKGROUND

The enzyme dipeptidyl peptidase IV, herein abbreviated DP-IV (and elsewhere as DAP-IV or DPP-IV) and also known by the classification EC.3.4.14.5, is a serine protease that cleaves the N-terminal dipeptide from peptides that begin with the sequence H-Xaa-Pro (where Xaa is any amino acid, although preferably a lipophilic one, and Pro is praline). It will also accept as substrates peptides that begin with the sequence H-Xaa-Ala (where Ala is alanine). DP-IV was first identified as a membrane-bound protein. More recently a soluble form has been identified.

Initial interest in DP-IV focussed on its role in the activation of T lymphocytes. DP-IV is identical to the T cell protein CD26. It was proposed that inhibitors of DP-IV would be capable of modulating T cell responsiveness, and so could be developed as novel immunomodulators. It was further suggested that CD26 was a necessary co-receptor for HIV, and thus that DP-IV inhibitors could be useful in the treatment of AIDS.

Attention was given to the role of DP-IV outside the immune system. It was recognised that DP-IV has a key role in the degradation of several peptide hormones, including growth hormone releasing hormone (GHRH) and glucagon-like peptide-1 and -2 (GLP-1 and GLP-2). Since GLP-1 is known to have a potentiating effect on the action of insulin in the control of post-prandial blood glucose levels it is clear that DP-IV inhibitors might also be usefully employed in the treatment of type II diabetes and impaired glucose tolerance. At least two DP-IV inhibitors are currently undergoing clinical trials to explore this possibility.

Several groups have disclosed inhibitors of DP-IV. While some leads have been found from random screening programs, the majority of the work in this field has been directed towards the investigation of substrate analogues. Inhibitors of DP-IV that are substrate analogues are disclosed in, for example, US 5,462,928, US 5,543,396, WO95/15309 (equivalent to US 5,939,560 and EP 0731789), W098/19998 (equivalent to US 6,011 ,155), W099/46272 and WO99/61431. The most potent inhibitors are aminoacyl pyrrolidine boronic acids, but these are unstable and tend to cyclise, while the more stable pyrrolidine and thiazolidine derivatives have a lower affinity for the enzyme and so would require large doses in a clinical situation. Pyrrolidine nitriles appear to offer a good compromise since they have both a high affinity for the enzyme and a reasonably long half-life in solution as the free base. There remains, however, a need for inhibitors of DP-IV with improved properties.

SUMMARY OF THE INVENTION

The present invention relates to a series of prodrugs of inhibitors of DP-IV with improved properties. The compounds can be used for the treatment of a number of human diseases, including impaired glucose tolerance and type II diabetes. Accordingly, the invention further relates to the use of the compounds in the preparation of pharmaceutical compositions, to such compositions per se, and to the use of such compositions in human therapy. The compounds of the invention are described by general formula 1.

In this general formula R¹ is H or CN; R² is selected from CH₂R⁵, CH₂CH₂R⁵ and C(R³)(R⁴)-X²-(CH₂)_aR^s; R³ and R⁴ are each independently selected from H and Me; R⁵ is selected from CON(R⁶)(R⁷), N(R⁸)C(=0)R⁹, N(R⁸)C(=S)R⁹, N(R⁸)S0₂R¹⁰ and N(R⁸)R¹⁰; R⁶ and R⁷ are each independently R¹¹(CH₂)_b or together they are -(CH₂)₂-Z-(CH₂)₂- or -CH₂-o-C₆H4-Z-CH₂-; R⁸ is H or Me; R⁹ is selected from R¹¹(CH₂)_b, R¹¹(CH₂)_bO and N(R⁶)(R⁷); R¹⁰ is R¹¹(CH₂)_b; R¹¹ is selected from H, alkyl, optionally substituted aryl, optionally substituted aroyl, optionally substituted arylsulphonyl and optionally substituted heteroaryl; R¹² is selected from H₂NCH(R¹³)CO, H₂NCH(R¹⁴)CONHCH(R¹⁵)CO, C(R¹⁶)=C(R¹⁷)COR¹⁸ and R¹⁹OCO; R¹³, R¹⁴ and R¹⁵ are selected from the side chains of the proteinaceous amino acids; R¹⁶ is selected from H, lower alkyl (d - C₆) and phenyl; R¹⁷ is selected from H and lower alkyl (d - C₆); R¹⁸ is selected from H, lower alkyl (d - C₆), OH, 0-(lower alkyl (d - C₆)) and phenyl; R¹⁹ is selected from lower alkyl (d - C₆), optionally substituted phenyl and R²⁰C(=O)OC(R²¹)(R²²); R²⁰, R²¹ and R²² are each independently selected from H and lower alkyl (d - C₆); Z is selected from a covalent bond, -(CH₂)_C-, -0-, -SO_d- and - N(R¹⁰)-; X¹ is S or CH₂; X² is O, S or CH₂; a is 1 , 2 or 3; b is 0 - 3; c is 1 or 2; and d is 0, 1 or 2.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect, the present invention relates to a series of novel compounds that are prodrugs of inhibitors of DP-IV with improved properties. The compounds of the invention are described by general formula 1.

In this general formula R¹ is either a hydrogen atom (H) or a nitrile group (-CN) and X¹ is either a sulphur atom (S) or CH₂. In one preferred embodiment of the invention, R is H. In another preferred embodiment, R¹ is CN.

R² is selected from a group according to CH₂R⁵, a group according to CH₂CH₂R⁵ and a group according to C(R³)(R⁴)-X²-(CH₂)_aR⁵, where R³ and R⁴ are each independently selected from H and a methyl group (Me), X² is O, S or CH₂ and a is 1 , 2 or 3. Preferably R² is selected from a group according to CH₂CH₂R^S and a group according to C(R³)(R⁴)-X²-(CH₂)_aR⁵. More preferably R² is selected from a group according to CH₂CH₂R⁵ and a group according to C(R³)(R⁴)-X²-(CH₂)_aR⁵ where R³ and R⁴ are both H, X² is CH₂ and a is 1 or 2. Most preferably R² is selected from a group according to CH₂CH₂CH₂R⁵ and a group according to CH₂CH₂CH₂CH₂R⁵.

R⁵ is selected from a group according to CON(R⁶)(R⁷), a group according to N(R⁸)C(=0)R⁹, a group according to N(R⁸)C(=S)R⁹, a group according to N(R⁸)S0₂R¹° and a group according to N(R⁸)R¹⁰. In one preferred embodiment of the invention, R⁵ is a group according to CON(R⁶)(R⁷). In another preferred embodiment, R⁵ is selected from a group according to N(R⁸)C(=O)R⁹, a group according to N(R⁸)C(=S)R⁹, a group according to N(R⁸)SO₂R¹⁰ and a group according to N(R⁸)R¹⁰. R⁶ and R⁷ may each independently a group according to R¹¹(CH₂)_b, where b is 0 - 3. Alternatively they may together be a chain -(CH₂)₂-Z-(CH₂)₂- or -CH₂-o-C₆H₄-Z-CH₂-, where Z is selected from a covalent bond, -(CH₂)_C-, -O-, -SO_d- and -N(R¹⁰)-, c is 1 or 2; and d is 0, 1 or 2, such that, together with the nitrogen atom to which they are attached, they form a five-, six- or seven-membered ring.

R⁸ is H or Me.

R⁹ is selected from a group according to R¹¹(CH₂) , a group according to R¹¹(CH₂)_bO and a group according to N(R⁶)(R⁷).

R¹⁰ is a group according to R¹¹(CH₂)_b.

R¹¹ is selected from H, alkyl, optionally substituted aryl, optionally substituted aroyl, optionally substituted arylsulphonyl and optionally substituted heteroaryl.

The term alkyl, as used herein, denotes saturated hydrocarbon groups with between 1 and 10 carbon atoms, including straight-chain, branched and mono- and polycycloalkyl groups, such as methyl, ethyl, propyl, isopropyl, π-butyl, fe -butyl, cyclopentyl, cyclohexyl, cyclohexylmethyl, 2-cyclohexyl-2-propyl, bicyclo[2.2.2]octyl and the like.

The term aryl, as used herein, denotes monocyclic and fused bicyclic aromatic groups, including carbocyclic groups, such as phenyl and naphthyl, and heteroaryl groups with up to three heteroatoms selected from nitrogen, oxygen and sulphur, such as pyrrolyl, furyl, thienyl, pyrazolyl, imidazolyl, oxazolyl, isothiazolyl, pyridyl, pyrimidinyl, indolyl, quinolinyl and the like. Unless otherwise specified, an aryl, aroyl, arylsulphonyl or heteroaryl group may optionally be substituted with up to three groups independently selected from alkyl, OH, alkoxy, O-alkyl, Cl, F, Br, NH₂, amino (including alkylamino NH-alkyl and dialkylamino N(alkyl)₂), C0₂H, C0₂-alkyl, CONH₂, CONH-alkyl, CON(alkyl)_2l acyl, carboxy, carboxyalkyl, carboxamido, N0₂ and CN.

R¹² is selected from a group according to H₂NCH(R¹³)CO, a group according to H₂NCH(R¹⁴)CONHCH(R¹⁵)CO, a group according to C(R¹⁶)=C(R ⁷)COR¹⁸ and a group according to R¹⁹OCO. In one preferred embodiment of the invention R¹² is selected from a group according to H₂NCH(R¹³)CO and a group according to H₂NCH(R¹⁴)CONHCH(R¹⁵)CO. In another preferred embodiment of the invention R¹² is a group according to R¹⁹OCO.

R¹³, R¹⁴ and R ⁵ are selected from the side chains of the proteinaceous amino acids, as listed in the following Table.

R¹ is selected from H, lower alkyl (d - C₆ alkyl) and phenyl.

R¹⁷ is selected from H and lower alkyl (d - C₆).

R¹⁸ is selected from H, lower alkyl (d - C₆), OH, O-(lower alkyl (d - C₆)) and phenyl. R is selected from lower alkyl (d - C₆), optionally substituted phenyl and R²⁰C(=O)OC(R²¹)(R²²).

R²⁰, R²¹ and R²² are each independently selected from H and lower alkyl (d - C₆).

In a preferred embodiment, X¹ is CH₂and R¹ is CN. For this embodiment, preferred R⁵ groups are CON(R⁶)(R⁷), N(R⁸)C(=0)R⁹, N(R⁸)C(=S)R⁹ and N(R⁸)R¹⁰. In another preferred embodiment, X¹ is CH₂ and R¹ is H. In another preferred embodiment X¹ is S. In a further preferred embodiment X¹ is S and R¹ is H.

Preferred compositions according to the invention may have improved activity and/or improved pharmacological profile. Preferred compositions may have in vivo stability characteristics which make them particularly suitable for use as pro-drugs.

Certain of the compounds of the present invention have acidic or basic properties and so can exist as salts. Insofar as such salts are non-toxic and otherwise pharmaceutically acceptable, they are included within the scope of the invention. Examples of such salts include, but are not limited to, the acetate, hydrochloride, sulphate, phosphate and benzoate salts of basic compounds, and the sodium, potassium and tetra-alkyl ammonium salts of acidic compounds.

Following administration, the compounds of the present invention are transformed into compounds according to general formula 2. These compounds are potent inhibitors of dipeptidyl peptidase IV.

Accordingly, the compounds of the invention can be used for the treatment of a number of human diseases, including impaired glucose tolerance and type II diabetes. Further aspects of the invention therefore relate to the use of the compounds in the preparation of pharmaceutical compositions, to such compositions per se, and to the use of such compositions in human therapy. The compounds of the present invention may be prepared according to methods that are well known in the field of organic chemistry, and particularly peptide chemistry. One strategy is to prepare the corresponding primary amine according to general formula 2 and then derivatise this.

When R¹² is H₂NCH(R¹³)CO then the final transformation may be accomplished in two steps by the reaction of 2 with a protected amino acid derivative followed by a deprotection step.

In the above scheme, PG is a protecting group such as tert-butyloxycarbonyl (BOC), 9-fluorenylmethyloxycarbonyl (FMOC) or benzyloxycarbonyl.

When R¹² is H₂NCH(R¹⁴)CONHCH(R¹⁵)CO then the final transformation may be accomplished analogously by the reaction of 2 with a protected dipeptide derivative followed by a deprotection step, or in a slightly longer way with two cycles of coupling and deprotection.

or

When R¹² is C(R¹⁶)=C(R¹⁷)COR¹⁸ then the final transformation may be accomplished by the reaction of 2 with a suitable 1 ,3-dicarbonyl compound.

When R¹² is R¹⁹OCO then the final transformation may be accomplished by the reaction of 2 with a suitable active carbonic acid half ester derivative, such as a chloroformate or a para-nitrophenyl carbonate.

The intermediate 2 may be prepared by the coupling of a protected amino acid with a pyrrolidine or thiazolidine derivative, followed by a deprotection step.

Alternatively, it may be more convenient to elaborate the functionality of R² after the assembly of the backbone of 2.

These general methods are further illustrated in the following non-limiting Examples.

EXAMPLE 1

(2S)-1-[Λ/^α-(1'-Acetoxyethoxycarbonyl)- /^ω-(pyrazinyl-2-carbonyl)-L-ornithinyl]- pyrrolidine-2-carbonitrile

1A. A/-(2-Nitrobenzenesulphenyl)-L-proline

L-Proline (25g, 217mmol) was dissolved in 2M NaOH (110ml, 220mmol) and dioxan (120ml). A solution of 2-nitrobenzenesulphenyl chloride (42g, 222mmol) in dioxan (60ml) was slowly added at the same time as 2M NaOH (110ml, 220mmol). The mixture was stirred for 2 hours at room temperature then poured into water (500ml). The solid was removed by filtration. The pH of the filtrate was adjusted to pH3 with 2M HCI and the solution was extracted with ethyl acetate (3 x 500ml). The combined organic extracts were washed with water (4 x 200ml) and brine (1 x 200ml), dried (Na₂S0₄) and evaporated in vacuo to give an orange solid identified as Λ/-(2- nitrobenzenesulphenyl)-L-proline (58.1g, 217mmol, 100%).

1B. Λ/-(2-Nitrobenzenesulphenyl)-L-ρroline succinimidyl ester

Λ/-(2-Nitrobenzenesulphenyl)-L-proline (57.9g, 216mmol) was dissolved in CH₂CI₂/DMF (9:1 , 500ml). Λ/-Hydroxysuccinimide (37.3g, 324mmol) and water-soluble carbodiimide (51.8g, 260mmol) were added. The mixture was stirred for 18 hours at room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (1000ml). The solution was washed with water (4 x 200ml) and brine (1 x 200ml), dried (Na₂SO₄) and evaporated in vacuo to give a yellow solid identified as N- (2-nitrobenzenesulphenyl)-L-proline succinimidyl ester (78.9g, 216mmol, 100%). 1 C. /v-(2-Nitrobenzenesulphenyl)-L-prolinamide

Λ/-(2-Nitrobenzenesulphenyl)-L-proline succinimidyl ester (78.5g, 215mmol) was dissolved in dioxan (500ml). Ammonia (35%, 100ml) was added. The mixture was stirred at room temperature for 2 hours then poured into water (700ml). The precipitate was collected, washed with water (200ml), dried over P₂0₅ and recrystallised from ethyl acetate/pet ether 60-80 to give a yellow solid identified as Λ/- (2-nitrobenzenesulphenyl)-L-prolinamide (49.6g, 185mmol, 86%).

1 D. (2S)-1 -(2-Nitrobenzenesulphenyl)pyrrolidine-2-carbonitrile

Λ/-(2-Nitrobenzenesulphenyl)-L-prolinamide (49g, 183mmol) was dissolved in dry THF (300ml). The solution was cooled to 0°C, triethylamine (36.7g, 367mmol) was added followed by the slow addition of trifluoroacetic anhydride (77g, 367mmol). The pH was adjusted to pH9 with triethylamine. The mixture was stirred for 30min then diluted with ethyl acetate (500ml), washed with water (1 x 200ml) and brine (1 x 200ml), dried (Na₂S0₄) and evaporated in vacuo to give an orange oil which was purified by flash chromatography on silica gel (eluant: 80% pet ether 60-80, 20% ethyl acetate) to give a yellow solid identified as (2S)-1-(2-nitrobenzenesulphenyl)pyrrolidine-2-carbonitrile (38.9g, 150mmol, 82%).

1 E. (2S)-Pyrrolidine-2-carbonitrile hydrochloride

(2S)-1-(2-nitrobenzenesulphenyl)pyrrolidine-2-carbonitrile (38.5g, 149mmol) was dissolved in diethyl ether (200ml). 4M HCI/Dioxan (150ml, δOOmmol) was slowly added. The mixture was stirred for 2h at room temperature then poured into diethyl ether (1000ml). The solid was collected, washed with diethyl ether (500ml) and recrystallised from methanol/diethyl ether to give a white solid identified as (2S)- pyrrolidine-2-carbonithle hydrochloride (18.9g, 142.5mmol, 96%).

1F. (2S)-1-[Λ/^α-(ter -Butyloxycarbonyl)-Λ -(pyrazinyl-2-carbonyl)-L-ornithinyl]- pyrrolidine-2-carbonitrile.

Λ/^α-(tert-Butyloxycarbonyl)-ΛT-(pyrazinyl-2-carbonyl)-L-ornithine (2.5g, 7.4mmol) was dissolved in CH₂CI₂ (50ml). This solution was cooled to 0°C, (2S)-pyrrolidine-2- carbonitrile hydrochloride (1.2g, 9.1 mmol) and PyBOP (4.3g, 8.23mmol) were added, and the pH adjusted to pH9 with triethylamine. The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (200ml). The solution was washed with 0.3M KHS0₄ (2 x 50ml), sat. NaHC0₃ (2 x 50ml), water (2 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo to give a yellow oil which was purified by flash chromatography on silica gel (eluant: 80% ethyl acetate, 20% pet. ether, 60-80) to give a colourless oil identified as (2S)-1 -[Λ/^α-(ferf-butyloxycarbonyl)-/V^ω-(pyrazinyl-2-carbonyl)-L-ornithinyl]- pyrrolidine-2-carbonitrile (2.98g, 7.16mmol, 97%).

1G. (2S)-1-[AT-(Pyrazinyl-2-carbonyl)-L-ornithinyl]pyrrolidine-2-carbonitrile trifluoroacetate

(2S)-1-[/V -fert-Butyloxycarbonyl-/\T-(pyrazinyl-2-carbonyl)-L-omithinyl]pyrrolidine-2- carbonitrile (2.8g, 6.7mmol) was dissolved in trifluoroacetic acid (5ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo to give a colourless oil identified as (2S)-1-[ΛT-(pyrazinyl-2-carbonyl)-L- omithinyl]pyrrolidine-2-carbonitrile trifluoroacetate (1.5g, 3.48mmol, 52%).

1H. (ΣSJ-l-tΛ/^l'-Acetoxyethoxycarbony -Λ^-tpyrazinyl-Σ-carbonylJ-L-ornithinyl]- pyrrolidine-2-carbonitrile

A solution of (2S)-1-[/\ -(pyrazinyl-2-carbonyl)-L-omithinyl]pyrrolidine-2-carbonitrile trifluoroacetate (200mg, 0.47mmol), α-acetoxyethyl p-nitrophenyl carbonate (140mg, 0.52 mmol; prepared according to Alexander et al., J. Med. Chem. 31 , 318, 1988) and triethylamine (60mg, 0.6mmol) in dichloromethane (25ml) was stirred at room temperature for 18 hours then evaporated in vacuo. The residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 98% chloroform, 2%methanol) to give a white solid identified as (2S)-1-[Λ/ - (1'-acetoxyethoxycarbonyl)-Λ -(pyrazinyl-2-carbonyl)-L-ornithinyl]pyrrolidine-2- carbonitrile (30mg, 0.07mmol,14%).

[M+H]⁺ = 447.2

¹H NMR (CDCI₃): δ 1.41-1.48 (3H,m), 1.72-1.86 (4H,m), 2.02 (3H,d,J=7.7Hz), 2.11-2.28 (4H,m), 3.51-3.57 (2H,m), 3.68-3.69 (2H,m), 4.47-4.48 (1 H,m), 4.74-4.76 (1 H,m), 5.55- 5.59 (1 H,m), 6.75-6.78 (1 H,m), 7.89-7.91 (1 H,m), 8.52 (1 H,d,J=1.9Hz), 8.76 (1 H,d,J=2.5Hz), 9.3 (1 H,d,J=1.5Hz) ppm. EXAMPLE 2

(4R)-3-[N^α-Methoxycarbonyl)-ΛP-(pyrazinyl-2-carbonyl)-L-lysinyl]thiazolidine-4- carbonitrile

2A. (4R)-3-(tert-Butyloxycarbonyl)thiazolidine-4-carboxamide

(4R)-3-(tert-Butyloxycarbonyl)thiazolidine-4-carboxylic acid (12.5g, 54.1 mmol) was dissolved in CH₂CI₂/DMF (9:1 , 150ml). To this solution at 0°C was added 1-hydroxybenzotriazole hydrate (14.6g, 108mmol) and water-soluble carbodiimide (13.0g, 65mmol). The mixture was stirred for 1 hour at 0°C then ammonia (35%, 50ml) was added. The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (500ml). The solution was washed with 0.3M KHS0₄ (2 x 100ml), sat. NaHCO₃ (2 x 100ml), water (2 x 100ml) and brine (1 x 100ml), dried (Na₂S0₄) and evaporated in vacuo to give a yellow oil. The residue was purified by flash chromatography on silica gel (eluant: 2% methanol, 98% chloroform) to give a colourless oil identified as (4R)-3-(fert- butyloxycarbonyl)thiazolidine-4-carboxamide (8.9g, 38.4mmol,71 %).

2B. (4R)-Thiazolidine-4-carboxamide hydrochloride

(4S)-3-(fert-Butyloxycarbonyl)thiazolidine-4-carboxamide (8.6g, 37.1mmol) was dissolved in 4M HCI/dioxan (50ml). The mixture was stirred for 1 hour at room temperature then the solvent was evaporated in vacuo to give a white solid identified as (4R)-thiazolidine-4-carboxamide hydrochloride (6.2g, 36.8mmol, 99%).

2C. (4R)-3-[Λ/^α-(teft-Butyloxycarbonyl)-/V^ω-(9-fluorenylmethyloxycarbonyl)-L- lysinyl]thiazolidine-4-carboxamide

/v^α-(tert-Butyloxycarbonyl)-ΛT-(9-fluorenylmethyloxycarbonyl)-L-lysine (5g, 10Jmmol) was dissolved in CH₂CI₂ (100ml). This solution was cooled to 0°C, (4R)-thiazolidine-4- carboxamide hydrochloride (1.78g, 11.7mmol) and PyBOP (6.7g, 12.8mmol) were added, and the pH was adjusted to pH9 with triethylamine. The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (200ml). The solution was washed with 0.3M KHS0₄ (2 x 50ml), sat. NaHC0₃ (2 x 50ml), water (2 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo to give a yellow oil. The residue was purified by flash chromatography on silica gel (eluant: 2% methanol, 98% chloroform) to give a colourless oil identified as (4R)-3-[/V^α-(fert-butyloxycarbonyl)-ΛT-(9-fluorenylmethyloxy- carbonyl)-L-lysinyl]thiazolidine-4-carboxamide (2.81 g, 4.8mmol, 44%).

2D. (4R)-3-[Λ/^α-(tert-Butyloxycarbonyl)-Λ/^ω-(9-fluorenylmethyloxycarbonyl)-L- lysinyl]thiazolidine-4-carbonitrile

(4R)-3-[/V^a-(fe/ -Butyloxycarbonyl)-/\T-(9-fluorenylmethyloxycarbonyl)-L-lysinyl]- thiazolidine-4-carboxamide (2.7g, 4.7mmol) was dissolved in dry THF (100ml). The solution was cooled to 0°C and triethylamine (1.0g, 10mmol) was added followed by the slow addition of trifluoroacetic anhydride (2.0g, 9.5mmol). The pH was adjusted to pH9 with triethylamine. The mixture was stirred for 30min then diluted with ethyl acetate (100ml), washed with water (1 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 60% pet ether 60-80, 40% ethyl acetate) to give a colourless oil identified as (4R)-3-[Λ/^α-(fert-butyloxycarbonyl)-Λ/^ω-(9-fluorenylmethyloxycarbonyl)-L-lysinyl]- thiazolidine-4-carbonitrile (2.14g, 3.81 mmol, 82%).

2E. (4R)-3-[Λ/^α-(fert-Butyloxycarbonyl)-L-lysinyl]thiazolidine-4-carbonitrile

(4R)-3-[/V^α-(fe/ -Butyloxycarbonyl)-ΛT-(9-fluorenylmethyloxycarbonyl)-L-lysinyl]- thiazolidine-4-carbonitrile (1.9g, 3.4mmol) was dissolved in THF (40ml). Diethylamine (10ml) was added. The mixture was stirred for 2h at room temperature then the solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 90% chloroform, 7% methanol, 3% triethylamine) to give a colourless oil identified as (4R)-3-[Λ/ -(fen*-butyloxycarbonyl)-L-lysinyl]thiazolidine-4-carbonitrile (863mg, 2.5mmol, 75%).

2F. (4R)-3-[Λ/^α-(fe/ -Butyloxycarbonyl)-Λ/^ω-(pyrazinyl-2-carbonyl)-L-lysinyl]- thiazolidine-4-carbonitrile

(4R)-3-[Λ/^α-(fen'-Butyloxycarbonyl)-L-lysinyl]thiazolidine-4-carbonitrile (100mg,

0.29mmol) was dissolved in CH₂CI₂ (20ml). To this solution at 0°C were added 2- pyrazinecarboxylic acid (43mg, 0.35mmol) and PyBOP (170mg, 0.33mmol) and the pH was adjusted to pH9 with triethylamine. The mixture was stirred for 18 h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHS0₄ (2 x 20ml), sat. NaHC0₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 2% methanol, 98% chloroform) to give a colourless oil identified as (4R)-3-[/V^α- (fert-butyloxycarbonyl)-/V^ω-(pyrazinyl-2-carbonyi)-L-lysinyi]thiazolidine-4-carbonitrile (112mg, 0.25mmol, 86%).

2G. (4R)-3-[( /V VIethoxycarbonyl)- Λ/^ω-(pyrazinyl-2-carbonyl)-L-lysinyl]- thiazolidine-4-carbonitrile

(4R)-3-[/V^α-(ferf-Butyloxycarbonyl)-Λ -(pyrazinyl-2-carbonyl)-L-lysinyl]thiazolidine-4- carbonithle (160mg, 0.36mmol) was dissolved in 4M HCI/dioxan (30ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25 ml). Methyl chloroformate (50mg, 0.53mmol) and triethylamine (60mg, 0.6 mmol) were added and the solution was stirred at room temperature for 18 hours then solution was evaporated in vacuo. The residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 90% ethyl acetate: 10% pet. ether 60-80) to give a white solid identified as (4R)-3-[(Λ/^α-methoxycarbonyl)-ΛP-(pyrazinyl-2- carbonyl)-L-lysinyl]thiazolidine-4-carbonitrile (52mg, 0.13mmol, 35%).

[M+H]⁺ = 407.1

¹H NMR (CDCI₃): δ 1.33-1.48 (4H,m), 1.63-1.82 (2H,m), 3.21-3.27 (2H,m), 3.45-3.60 (2H,m), 3.63 (3H,s), 4.44-4.46 (1 H,m), 4.63 (1 H,d,J=8.4Hz), 4.86 (1 H,d,J=8.5Hz), 5.23- 5.27 (1 H,m), 5.53 (1 H,d,J=8.2Hz), 7.85-7.87 (1 H,m), 8.50-8.51 (1 H,m), 8.73 (1 H,d,J=2.5Hz), 9.38 (1 H,d,J = 1 ,3Hz) ppm.

EXAMPLE 3

(4R)-3-[N^α-(1'-Acetoxyethoxycarbonyl)-Λ/^ω-(3-cyanobenzenesulphonyl)-L- ornithinyl]thiazolidine-4-carbonitrile

3A. (4R)-3-[Λ/^α-(tert-Butyloxycarbonyl)-Λ/^ω-(9-fluorenylmethyloxycarbonyl)-L- ornithinyl]thiazolidine-4-carboxamide

/V^α-(fert-Butyloxycarbonyl)-/\ -(9-fluorenylmethyloxycarbonyl)-L-ornithine (2.8g,

6.2mmol) was dissolved in CH₂CI₂ /DMF (9:1, 100ml). This solution was cooled to 0°C, (4R)-thiazolidine-4-carboxamide hydrochloride (1.78g, 11.7mmol), 1- hydroxybeπzotriazole hydrate (1.1g, 8.1mmol) and water-soluble carbodiimide (1.5g, 7.5mmol) were added, and the pH was adjusted to pH8 with N-methylmorpholine. The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (200ml). The solution was washed with 0.3M KHS0₄ (2 x 50ml), sat. NaHC0₃ (2 x 50ml), water (2 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo to give a yellow oil. The residue was purified by flash chromatography on silica gel (eluant: 85% ethyl acetate, 15% pet. ether 60-80) to give a colourless oil identified as (4R)-3-[Λ/°-(tert- butyloxycarbonyl)-ΛT-(9-fluorenylmethyloxycarbonyl)-L-ornithinyl]thiazolidine-4- carboxamide (2.26g, 3.9mmol, 66%).

3B. (4R)-3-[Λ/^α-(tert-Butyloxycarbonyl)-Λ ^ω-(9-fluorenylmethyloxycarbonyl)-L- ornithinyl]thiazolidine-4-carbonitrile

(4R)-3-[Λ/^α-(fert-Butyloxycarbonyl)-ΛT-(9-fluorenylmethyloxycarbonyl)-L-ornithinyl]- thiazolidine-4-carboxamide (2.1g, 3.7mmol) was dissolved in dry THF (100ml). The solution was cooled to 0°C, triethylamine (740mg, 7.4mmol) was added followed by the slow addition of trifluoroacetic anhydride (1.65g, 7.9mmol). The pH was adjusted to pH9 with triethylamine. The mixture was stirred for 30min then diluted with ethyl acetate (100ml), washed with water (1 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 45% pet ether 60-80, 55% ethyl acetate) to give a colourless oil identified as (4R)-3-[/V^α-(ferf-butyloxycarbonyl)-/V^ω-(9-fluorenylmethyloxycarbonyl)-L-ornithinyl]- thiazolidine-4-carbonithle (1.73g, 3.14mmol, 85%).

3C. (4R)-3-[Λ/^α-(tert-Butyloxycarbonyl)-L-omithinyl]thiazolidine-4-carbonitrile

(4R)-3-[/V^α-(fert-Butyloxycarbonyl)-/V^ω-(9-fluorenylmethyloxycarbonyl)-L-ornithinyl]- thiazolidine-4-carbonitrile (1.6g, 2.9mmol) was dissolved in THF (40ml). Diethylamine (10ml) was added. The mixture was stirred for 2h at room temperature then the solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 90% chloroform, 7% methanol, 3% triethylamine) to give a colourless oil identified as (4R)-3-[/V^α-(fert-butyloxycarbonyl)-L-omithinyl]thiazolidine-4-carbonitrile (902mg, 2.75mmol, 95%).

3D. (4R)-3-[W^α-(tert-Butyloxycarbonyl)-Λ/^ω-(3-cyanobenzenesulphonyl)-L- ornithinyl]thiazolidine-4-carbonitrile

(4R)-3-[/V^α-(fert-Butyloxycarbonyl)-L-ornithinyl]thiazolidine-4-carbonitrile (207mg,

0.63mmol) was dissolved in CH₂CI₂ (25ml). To this solution at 0°C was added 3- cyanobenzenesulphonyl chloride (135mg, 0.67mmol) and the pH was adjusted to pH9 with triethylamine. The mixture was stirred for 18 h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHS0₄ (2 x 20ml), sat. NaHC0₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0 ) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 45% ethyl acetate: 55% pet. ether 60-80°C) to give a colourless oil identified as (4R)-3-[/V^I-(fe/ - butyloxycarbonyl)-ΛT-(3-cyanobenzenesulphonyl)-L-ornithinyl]thiazolidine-4-carbonitπϊe (162mg, 0.33mmol, 52%).

3E. (4R)-3-[N^ct-(1'-Acetoxyethoxycarbonyl)-Λ/^ω-(3-cyanobenzenesulphonyl)-L- ornithinyl]thiazolidine-4-carbonitrile

(4R)-3-[/V^α-(fe f-Butyloxycarbonyl)-ΛT-(3-cyanobenzenesulphonyl)-L-omithinyl]- thiazolidine-4-carbonitrile (142mg, 0.29mmol) was dissolved in trifluoroacetic acid (5ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and α- acetoxyethyl p-nitrophenyl carbonate (108mg, 0.40 mmol; prepared according to Alexander ef al., J. Med. Chem. 31 , 318, 1988) and triethylamine (60mg, 0.6mmol) were added. The reaction was stirred at room temperature for 18 hours, then evaporated in vacuo. The residue taken up in ethyl acetate (70ml) and the solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 70% ethyl acetate: 30% pet. ether 60-80) to give a white solid identified as (4R)-3-[Λ/°-(1'- acetoxyethoxycarbonyl)-ΛT-(3-cyanobenzenesulphonyl)-L-ornithinyl]thiazolidine-4- carbonitrile (32mg, O.Oβmmol, 21%).

[M+H]⁺ = 524.0

¹H NMR (CDCI₃): δ 1.20-1.22 (2H,m), 1.43-1.46 (3H,m), 1.59-1.78 (4H,m), 2.03-2.06 (3H,m), 3.03 (2H,d,J=4.2Hz), 3.29-3.33 (2H,m), 4.61-4.66 (1H,m), 4.79-4.84 (1H,m), 5.16-5.20 (1H,m), 5.73-5.82 (1H,m), 6.74-6.76 (1 H,m), 7.63-7.69 (1 H,m), 7.83-7.86 (1H,m), 8.10-8.16 (2H,m) ppm.

EXAMPLE 4

(2S,2'S)-1-[2'-(1"-Acetoxyethoxycarbonylamino)-5'-oxo-5'-(tetrahydroisoquinolin-

2-yl)pentanoyl]pyrrolidine-2-carbonitrile

4A. (2S)-1-[/V-(tert-Butyloxycarbonyl)-O^ω-methyl-L-glutamyl]pyrrolidine-2- carbonitrile /-(fe/t-Butyloxycarbonyl)-O^ω-methyl-L-glutamic acid (1.0g, 3.83mmol) was dissolved in CH₂CI₂ /DMF (9:1 , 20ml). To this solution at 0°C were added 1-hydroxybenzotriazole hydrate (788mg, 5.84mmol), water-soluble carbodiimide (877mg, 4.38mmol), (2S)- pyrrolidine-2-carbonitrile hydrochloride (609mg, 4.6mmol) and triethylamine (65mg, 0.65mmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHS0₄ (2 x 20ml), sat. NaHC0₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 50% ethyl acetate, 50% pet. ether 60-80) to give a brown oil identified as (2S)-1-[Λ/-(fert-butyloxycarbonyl)-O^ω- methyl-L-glutamyl]pyrrolidine-2-carbonitrile (290mg, 0.86mmoi, 22%).

4B. (2S)-1-[Λ -(tert-Butyloxycarbonyl)-L-glutamyl]pyrrolidine-2-carbonitrile

(2S)-1-[Λ/-(ferf-Butyloxycarbonyl)-O^ω-methyl-L-glutamyl]pyrrolidine-2-carbonitrile (250mg, 0.74mmol) was dissolved in dioxan (5ml). 1M Lithium hydroxide (1.1ml, 1.1 mmol) was added. The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 1M KHS0₄ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo to give a colourless oil identified as (2S)-1-[Λ/-(fert-butyloxycarbonyl)-L-glutamyl]pyrrolidine-2-carbonitrile (200mg,

0.61 mmol, 83%).

4C. (2S,2'S)-1-[2'-(tert-Butyloxycarbonylamino)-5'-oxo-5'-(tetrahydroisoquinolin- 2-yl)peπtanoyl]pyrrolidine-2-carbonitrile

(2S)-1-[Λ/-(fe/t-Butyloxycarbonyl)-L-glutamyl]pyrrolidine-2-carbonitrile (200mg,

0.61 mmol) was dissolved in CH₂CI₂/DMF (9:1, 20ml). To this solution at 0°C were added 1-hydroxybenzotriazole hydrate (98mg, 0.73mmol), water-soluble carbodiimide (140mg, 0.73mmol), tetrahydroisoquinoline (109mg, 0.82mmol) and triethylamine(150mg, 1.5mmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHS0₄ (2 x 20ml), sat. NaHC0₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo to give a yellow oil. The residue was purified by flash chromatography on silica gel (eluant: 5% methanol, 97% chloroform) to give a colourless oil identified as .(2S,2'S)-1-[2'-(ferf-butyloxycarbonylamino)-5'-oxo-5'- (tetrahydroisoquinolin-2-yl)pentanoyl]pyrrolidine-2-carbonitrile (149mg, 0.34mmol, 56%). 4D. (2S,2'S)-1-[2'-(1"-Acetoxyethoxycarbonylamino)-5'-oxo-5'-(tetrahydro- isoquinolin-2-yl)pentanoyl]pyrrolidine-2-carbonitrile

(2S,2'S)-1-[2'-(fert-butyloxycarbonylamino)-5'-oxo-5'-(tetrahydroisoquinolin-2-yl)- pentanoyl]pyrrolidine-2-carbonitrile (149mg, 0.34mmol) was dissolved in trifluoroacetic acid (20ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and α- acetoxyethyl p-nitrophenyl carbonate (100mg, 0.37 mmol; prepared according to Alexander ef al., J. Med. Chem. 31 , 318, 1988) and triethylamine (40mg, 0.4mmol) were added. The reaction was stirred at room temperature for 18 hours then evaporated in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0 ) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 90% ethyl acetate, 10% pet. ether 60-80°C) to give a white solid identified as (2S,2'S)- 1-[2'-(1"-Acetoxyethoxycarbonylamino)-5'-oxo-5'-(tetrahydroisoquinolin-2- yl)pentanoyl]pyrrolidine-2-carbonitrile (58mg, 0.12mmol, 36%).

[M+H]⁺ = 471.2

¹H NMR (CDCI₃): δ 1.40-1.44 (3H,m), 2.00-2.07 (3H,m), 2.13-2.40 (9H,m), 2.82-2.91 (2H,m), 3.63-3.70 (2H,m), 3.96-4.18 (1 H,m), 4.57-4.61 (2H,m), 4.72-4.75 (2H,m), 5.78- 5.80 (1 H,m), 6.69-6.75 (1 H,m), 7.10-7.25 (4H,m) ppm.

EXAMPLE 5

(2S)-1-[/V^α-(4'-Oxopent-2'-en-2'-yl)-Λr-(quinoxalinyl-2-carbonyl)-L-ornithinyl]- pyrrolidine-2-carbonitrile

5A. l-tΛ^-tfert-Butyloxycarbony -Λ -tg-fluorenylmethyloxycarbony -L- omithinyl]-L-prolineamide

/V -(fert-Butyloxycarbonyl)-/V^ω-(9-fluorenylmethyloxycarbonyl)-L-ornithine (5g,

H.Ommol) was dissolved in CH₂CI₂ (40ml). This solution was cooled to 0°C, L- prolineamide (1.4g, 12.2 mmol) and PyBOP (6.3g, 12.1 mmol) were added, and the pH was adjusted to pH9 with triethylamine. The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in chloroform (200ml). The solution was washed with 0.3M KHS0₄ (2 x 50ml), sat. NaHC0₃ (2 x 50ml), water (2 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo to give a yellow oil. The residue was purified by flash chromatography on silica gel (eluant: 98% chloroform, 2% methanol) to give a colourless oil identified as 3-[W^α-(fert-butyloxycarbonyl)- T-(9- fluorenylmethyloxycarbonyl)-L-omithinyl]-L-prolineamide (4.2g, 7.6mmol, 69%).

5B. (2S)-1-[W^a-(fert-Butyloxycarbonyl)-/\T-(9-fluorenylmethyloxycarbonyl)-L- omithinyl]pyrrolidine-2-carbonitrile

^[/^-(fert-Butyloxycarbony -ΛT^Θ-fluorenylmethyloxycarbony -L-ornithinylj-L-proline- amide (4.1g, 7.4mmol) was dissolved in dry THF (100ml). The solution was cooled to 0°C and triethylamine (820mg, 8.2mmol) was added followed by the slow addition of trifluoroacetic anhydride (1.7g, 8.1mmol). The pH was adjusted to pH9 with triethylamine. The mixture was stirred for 30min then diluted with ethyl acetate (100ml), washed with water (1 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 20% ethyl acetate, 80% pet. ether 60-80) to give a colourless oil identified as (2S)-1-[Λf-(fert-butyloxycarbonyl)-ΛT-(9-fluorenylmethyloxycarbonyl)-L- ornithinyl]pyrrolidine-2-carbonitrile (3.5g, 6.5mmol, 87%).

5C. (2S)-1-[Λ/^α-(fert-Butyloxycarbonyl)-L-ornithinyl]pyrrolidine-2-carbonitrile

(2S)-1-[/V°-(tert-Butyloxycarbonyl)-A -(9-fluorenylmethyloxycarbonyl)-L-omithinyl]- pyrrolidine-2-carbonitrile (3.4g, 6.4mmol) was dissolved in THF (40ml). Diethylamine

(10ml) was added. The mixture was stirred for 2h at room temperature then the solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 90% chloroform, 7% methanol, 3% triethylamine) to give a colourless oil identified as (2S)-1-[/V^α-(terf-butyloxycarbonyl)-L-ornithinyl]pyrrolidine-2-carbonithle

(1.48g, 4.77mmol, 75%). 5D. (ΣSJ-l-tΛ ^tert-Butyloxycarbony -Λr^quinoxalinyl^-carbony -L-ornithinyl]- pyrrolidine-2 -carbonitrile

(2S)-1-[/V^α-(terf-Butyloxycarbonyl)-L-ornithinyl]pyrrolidine-2-carbonithle (300mg,

0.97mmol) was dissolved in CH₂CI₂ (25ml). To this solution at 0°C was added 2- quinoxaloyl chloride (200mg, 1.04mmol) and the pH was adjusted to pH9 with triethylamine. The mixture was stirred for 18 h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHS0₄ (2 x 20ml), sat. NaHCO₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 60% ethyl acetate, 40% pet. ether 60-80) to give a colourless oil identified as (2S)-1-[/V^α-(fert-butyloxycarbonyl)-ΛT- (quinoxaiinyl-2-carbonyl)-L-omithinyl]pyrrolidine-2-carbonitrile (31 Omg, 0.67mmol, 69%).

5E. (2S)-1-[Λ ^α-(4'-Oxopent-2'-en-2'-yl)-Λ/^ω-(quinoxalinyl-2-carbonyl)-L-ornithinyl]- pyrrolidine-2-carbonitrile

(2S)-1-[/V^α-(ferf-Butyloxycarbonyl)-ΛT-(quinoxalinyl-2-carbonyl)-L-ornithinyl]pyrrolidine- 2-carbonitrile (160mg, 0.34mmol) was dissolved in trifluoroacetic acid (20 ml). The mixture was stirred for one hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and 2,4-pentanedione (48mg, 0.48mmol) and triethylamine (100mg, I .Ommol) were added. The reaction was stirred at room temperature for 18 hours then evaporated in vacuo. The residue taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 98% chloroform, 2% methanol) to give a white solid identified as (2S)-1-[Λ/^α-(4'-oxopent-2'-en-2'-yl)-ΛT-(quinoxalinyl-2-carbonyl)-L- ornithinyl]pyrrolidine-2-carbonitrile (87mg, 0.19mmol, 57%).

[M+H]⁺ = 449.2

¹H NMR (CDCI₃): δ 1.89-2.02 (10H.2 x s+m), 2.13-2.24 (4H,m), 3.57-3.62 (5H,m), 4.3- 4.6 (1H,m), 4.70-4.81 (1H,m), 5.02 (1H,s), 7.83-7.88 (2H,m), 8.10-8.19 (3H,m), 9.62 (1H,s), 11.0-11.2 (1 H,m) ppm. EXAMPLE 6

(2S)-1-[Λ/-Acetoxymethoxycarbonyl-S-(3-picolylcarbamoylmethyl)-L-cysteinyl]- pyrrolidine-2-carbonitrile

6A. S-(Benzyloxycarbonylmethyl)-W-(tert-butyloxycarbonyl)-L-cysteine

Λ/-(ferf-Butyloxycarbonyl)-L-cysteine (3.5g, 15.8mmol), benzyl 2-bromoacetate (3.7g,16.1mmol) and triethylamine (1.8g, 18.0mmol) were dissolved in THF (100ml). The mixture was stirred for 18 hours at room temperature then diluted with ethyl acetate (100ml), washed with 0.3M KHS0 , sat NaHCO₃, water and brine, dried (Na₂S0 ) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 95% chloroform, 4% methanol, 1% acetic acid) to give a colourless oil identified as S-(benzyloxycarbonylmethyl)-Λ/-(tert-butyloxycarbonyl)-L- cysteine (5.2g, 14.1 mmol, 89%).

6B. (2S)-1-tS-(Benzyloxycarbonylmethyl)-Λ/-(tert-butyloxycarbonyl)-L-cysteinyl]- pyrrolidine-2-carbonitrile

S-(Benzyloxycarbonylmethyl)-Λ/-(terf-butyloxycarbonyl)-L-cysteine (5.1 Og, 13.8mmol) was dissolved in CH₂CI₂ (200ml). This solution was cooled to 0°C, (2S)-pyrrolidine-2- carbonitrile hydrochloride (2.1g, 15.8mmol) and PyBOP (8.0g, 15.3mmol) were added, and the pH adjusted to pH9 with triethylamine. The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (150ml). The solution was washed with 0.3M KHS0₄ (1 x 50ml), sat. NaHC0₃ (1 x 50ml), water (1 x 50ml) and brine (1 x 50ml), dried (Na₂SO₄) and evaporated in vacuo to give a yellow oil which was purified by flash chromatography on silica gel (eluant: 40% ethyl acetate, 60% pet. ether 60-80) to give a colourless oil identified as (2S)-1-[S-(benzyloxycarbonylmethyl)-Λ/-(tert-butyloxycarbonyi)-L- cysteinyl]pyrrolidine-2-carbonitrile (5.82g, 13.0mmol, 94%).

6C. (2S)-1-[W-(fert-Butyloxycarbonyl)-S-(carboxymethyl)-L-cysteinyl]pyrrolidine- 2 -carbonitrile

(2S)-1-[S-(Benzyloxycarbonylmethyl)-Λ/-(ferf-butyloxycarbonyl)-L-cysteinyl]pyrrolidine- 2-carbonithle (1.31 g, 2.9mmol) was dissolved in THF(100ml). 1 M Lithium hydroxide (3.5ml, 3.5mmol) was added. The mixture was stirred for 3 hours at room temperature then with ethyl acetate (100ml), washed with 1 M citric acid, water and brine, dried (Na₂S0₄) and evaporated in vacuo to give a colourless oil which was purified by flash chromatography on silica gel (eluant: 97% chloroform, 2% methanol, 1% acetic acid) to give a colourless oil identified as (2S)-1-[Λ/-(ferf-butyloxycarbonyl)-S-(carboxymethyl)-L- cysteinyl]pyrrolidine-2-carbonitrile (860mg, 2.4mmol, 82%).

6D. (2S)-1-[W-(tert-Butyloxycarbonyl)-S-(3-picolylcarbamoylmethyl))-L-cysteinyl]- pyrrolidine-2-carbonitrile

(2S)-1-[Λ/-(fert-Butyloxycarbonyl)-S-(carboxymethyl)-L-cysteinyl]pyrrolidine-2- carbonitrile (150mg, 0.42mmol) was dissolved in CH₂CI₂ (20ml). The solution was cooled to 0°C, 3-(aminomethyl)pyhdine (53mg, 0.5mmol) and PyBOP (270mg, 0.52mmol) were added, and the pH was adjusted to pH9 with triethylamine. The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was dissolved in ethyl acetate (70ml). The solution was washed with 0.3M KHS0₄ (1 x 20ml), sat. NaHC0₃ (1 x 20ml), water (1 x 20ml) and brine (1 x 20ml), dried (Na₂S0 ) and evaporated in vacuo to give a yellow oil which was purified by flash chromatography on silica gel (eluant: 96% chloroform, 4% methanol) to give a colourless oil identified as (2S)-1-[Λ/-(fert-butyloxycarbonyl)-S-(3- picolylcarbamoylmethyl))-L-cysteinyl]pyrrolidine-2-carbonitrile (170mg, 0.38mmol, 91%).

6E. (2S)-1-[Λ ^α-Acetoxymethoxycarbonyl-S-(3-picolylcarbamoylmethyl)-L- cysteinyl]pyrrolidine-2-carbonitrile

(2S)-1-[ /-(fert-Butyloxycarbonyl)-S-(3-picolylcarbamoylmethyl)-L-cysteinyl]pyrrolidine- 2-carbonitrile (130mg, 0.29mmol) was dissolved in trifluoroacetic acid (20ml). The solution was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and acetoxymethyl p- nitrophenyl carbonate (80mg, 0.31 mmol; prepared according to Alexander et al., J. Med. Chem. 31 , 318, 1988) and triethylamine (40mg, 0.4mmol) were added. The solution was stirred at room temperature for 18 hours then evaporated in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 90% ethyl acetate, 10% pet. ether 60-80) to give a white solid identified as (2S)-1-[Λ/^α-acetoxymethoxycarbonyl-S-(3- picolylcarbamoylmethyl)-L-cysteinyl]pyrrolidine-2-carbonitrile (33mg, 0.071 mmol, 24%).

[M+H]⁺ = 464.0

¹H NMR (CDCI₃): δ 2.08 (3H,s), 2.13-2.29 (4H,m), 2.89 (2H,d,J=6.9Hz), 3.20-3.29 (2H,m), 3.61-3.74 (2H,m), 4.46 (2H,d,J=5.9Hz), 4.60-4.71 (2H,m), 5.68 (2H,s), 6.12 (1H,d,J=8.6Hz), 7.16-7.27 (2H,m), 7.66 (1 H,d,J=8.1Hz), 8.50 (1 H,d,J=4.7Hz), 8.56 (1 H,s) ppm.

EXAMPLE 7

3-[Λ/^α-(1'- Acetoxyethoxycarbony -ΛT-^e-dichloronicotinoy -L-ornithinyl]- thiazolidine

7A. S-IΛ/^tert-ButyloxycarbonylJ-Λr-fθ-fluorenylmethyloxycarbony -L- ornithinyljthiazolidine

/V^α-(fert-Butyloxycarbonyl)-/V^ω-(9-fluorenylmethyloxycarbonyl)-L-ornithine (2.73g,

6mmol) was dissolved in CH₂CI₂/DMF (9:1 , 100ml). To this solution at 0°C were added 1-hydroxybenzotriazole hydrate (1.53g, 10mmol), water-soluble carbodiimide (1.34g, 7mmol), thiazolidine (1.28g, 18mmol) and triethylamine (80mg, δmmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (100ml). The solution was washed with 0.3M KHS0₄ (2 x 25ml), sat. NaHC0₃ (2 x 25ml), water (2 x 25ml) and brine (1 x 25ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 75% ethyl acetate, 25% pet. ether 60-80) to give a white solid identified as 3-[/V^α-(tert-butyloxycarbonyl)-/V^ω-(9- fluorenylmethyloxycarbonyl)-L-ornithinyl]thiazolidine (2.55g, 4.85mmol, 81%).

7B. S-IW^tert-Butyloxycarbony -L-ornithinyllthiazolidine

3-[/v^α-(ferf-Butyloxycarbonyl)-ΛT-(9-fluorenylmethyloxycarbonyl)-L-ornithinyl]thiazolidine (1.15g, 2.13mmol) was dissolved in acetonit le (20ml). Diethylamine (5ml) was added. The mixture was stirred for 90min at room temperature then the solvent was removed in vacuo and the residue was purified by flash chromatography on silica gel (eluant: 90% chloroform, 7% methanol, 3% triethylamine) to give a pale yellow oil identified as 3-[ /"-(terf-butyloxycarbonyl)-L-ornithinyl]thiazolidine (530mg, 1.67mmol, 78%).

7C. 3-[Λ/^α-(tert-Butyloxycarbonyl)-/V^ω-(5,6-dichloronicotinoyl)-L-omithinyl]- thiazolidine

3-[/V^α-(fert-Butyloxycarbonyl)-L-ornithinyl]thiazolidine (600mg, 1.96mmol) was dissolved in CH₂CI₂/DMF (9:1 , 50ml). To this solution at 0°C were added 1-hydroxybenzotriazole hydrate (360mg, 2.36mmol), water-soluble carbodiimide (472mg, 2.36mmol), 5,6- dichloronicotinic acid (416mg, 2.16mmol) and triethylamine (360mg, 3.6mmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHSO₄ (2 x 20ml), sat. NaHCO₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 2% methanol, 98% chloroform) to give a sticky white solid identified as 3-[/V -(fert-butyloxycarbonyl)-/V^ω-(5,6-dichloronicotinoyl)- L-omithinyl]thiazolidine (512mg, 1.08mmol, 56%).

7D. 3-[Λ ^α-(1'-Acetoxyethoxycarbonyl)-Λ -(5,6-dichloronicotinoyl)-L-omithinyl]- thiazolidine

3-[Λ/^α-(fert-Butyloxycarbonyl)-/V^ω-(5,6-dichloronicotinoyl)-L-ornithinyl]thiazolidine

(128mg, 0.27mmol) was dissolved in 4M HCI/dioxan (20ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and α-acetoxyethyl p-nitrophenyl carbonate (83mg, 0.3mmol; prepared according to Alexander ef al., J. Med. Chem. 31 , 318, 1988) and triethylamine (40mg, 0.4mmol) were added. The solution was stirred at room temperature for 18 hours then evaporated in vacuo. The residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 75% ethyl acetate, 25% pet. ether 60-80) to give a white solid identified as 3-[Λ/^α-(1'-acetoxyethoxycarbonyl)-/V^ω-(5,6-dichloronicotinoyl)-L-ornithinyl]thiazolidine (67mg, 0.13mmol, 47%).

[M+H]⁺ = 509.0

¹H NMR (CDCI₃): δ 1.44-1.46 (3H, m), 1.63-1.99 (3H,br m), 1.99-2.04 (4H,m), 2.98- 3.06 (2H,m), 3.46-3.48 (2H,m), 3.50-3.80 (2H,m), 4.47-4.56 (3H,m), 5.81-5.91 (1 H,m), 6.74-6.75 (1H,m), 7.24-7.33 (1H,m), 8.24-8.25 (1H,m), 8.69-8.71 (1H,m) ppm.

EXAMPLE 8 S-IW'-Methoxycarbonyl-Λ -tβ-trifluoromethylnicotinoylJ-L-ornithinyllthiazolidine

8A. S-I/V^ter -Butyloxycarbony -ΛT^δ-trifluoromethylnicotinoylJ-L-ornithinyl]- thiazolidine

3-[Λ/^α-(ten'-Butyloxycarbonyl)-L-ornithinyl]thiazolidine (150mg, 0.49mmol) was dissolved in CH₂CI₂/DMF (9:1 , 20ml). To this solution at 0°C were added 1-hydroxybenzotriazole hydrate (100mg, 0.74mmol), water-soluble carbodiimide (118mg, 0.59mmol), 6- trifluoromethylnicotinic acid (104mg, 0.54mmol) and triethylamine (100mg, I .Ommol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHS0 (2 x 20ml), sat. NaHC0₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 6% methanol, 94% chloroform) to give a sticky white solid identified as 3-[/V^α-(fert-butyloxycarbonyl)-ΛT-(6- trifIuoromethylnicotinoyl)-L-omithinyl]thiazolidine (76mg, 0.16mmol, 32%).

8B. S-IW-Methoxycarbonyl-Λ^-tδ-trifluoromethylnicotinoy -L-ornithinyl]- thiazolidine

3-[V^α-(te/ -Butyloxycarbonyl)-ΛT-(6-trifluoromethylnicotinoyl)-L-ornithinyl]thiazolidine (76mg, 0.16mmol) was dissolved in 4M HCI/dioxan (20ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and methyl chloroformate (17mg, 0.18 mmol) and triethylamine (20mg, 0.2mmol) were added. The solution was stirred at room temperature for 18 hours then evaporated in vacuo. The residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHCO₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 3% methanol, 97% chloroform) to give a white solid identified as 3-[N^α- methoxycarbonyl-AT-(6-thfluoromethylnicotinoyl)-L-ornithinyl]thiazolidine (66mg,

0.15mmol, 96%).

[M+H]⁺ = 435.1

¹H NMR (CDCI₃): δ 1.36-1.79 (4H,m), 2.98-3.11 (2H,m), 3.48-3.60 (2H,m), 3.64 (3H,s), 3.72-4.10 (3H,m), 4.57-4.60 (2H,m), 5.63-5.76 (1H,m), 6.55 (1H,br m), 7.54- 7.55(1 H,m), 8.77-8.79 (2H,m) ppm.

EXAMPLE 9 S-IΛ -tS.β-Dichloronicotinoy -Λ/^^-oxopent^'-en-Σ'-y -L-omithinyllthiazolidine

3-[/V^α-(fert-Butyloxycarbonyl)-Λ/^ω-(5,6-dichloronicotinoyl)-L-ornithinyl]thiazolidine (162mg, 0.34mmol) was dissolved in 4M HCI/dioxan (20ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and 2,4-pentanedione (100mg, 0.37 mmol) and triethylamine (40mg, 0.4mmol) were added. The solution was stirred at room temperature for 18 hours then evaporated in vacuo. The residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0 ) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 90% ethyl acetate, 10% pet. ether 60-80) to give a white solid identified as 3-[ΛT-(5,6-dichloronicotinoyl)-Λ/^α-4'-oxopent-2'-en-2'-yl)-L-ornithinyl]thiazolidine (63mg, 0.14mmol, 40%).

[M+H]⁺ = 461.3

¹H NMR (CDCI₃): δ 1.74-1.86 (6H,m), 1.87 (3H,s), 1.97 (3H,s), 2.94-3.11 (2H,m), 3.46- 3.51 (2H,m), 3.75-3.79 (1H,m), 4.48-4.57 (2H,m), 5.01 (1H,s), 7.60-7.90 (1H,m), 8.34 (1H,d,J=2.0Hz), 8.78 (1 H,d,J=2.3Hz), 11.01 (1H,d,J=8.2Hz) ppm.

EXAMPLE 10

3-[/V^α-(Acetoxymethoxycarbonyl)-N^ω-(3,4-dichlorobenzyl)-L- glutaminyl]thiazolidine

10A. 3-[W-(tert-Butyloxycarbonyl)-0"-methyl-L-glutamyl]thiazolidine

Λ/-(fert-Butyloxycarbonyl)-O^ω-methyl-L-glutamic acid (6.28g, 24mmol) was dissolved in CH₂CI₂/DMF (9:1 , 100ml). To this solution at 0°C were added 1-hydroxybenzotriazole hydrate (5.5g, 36mmol), water-soluble carbodiimide (5.38g, 28mmol), thiazolidine (2.48g, 28mmol) and triethylamine (3.0g, 30mmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (150ml). The solution was washed with 0.3M KHS0₄ (2 x 30ml), sat. NaHC0₃ (2 x 30ml), water (2 x 30ml) and brine (1 x 30ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 70% ethyl acetate, 30% pet. ether 60-80) to give a brown oil identified as 3- [Λ/-(tert-butyloxycarbonyl)-O^ω-methyl-L-glutamyl]thiazolidine (4.0g, 12mmol, 50%).

10B. 3-[Λ/-(tert-Butyloxycarbonyl)-L-glutamyl]thiazolidine

3-[Λ/-(tert-Butyloxycarbonyl)-O^ω-methyl-L-glutamyl]thiazolidine (3.23g, 9.73mmol) was dissolved in THF (50ml). 1M Lithium hydroxide (11ml, 11 mmol) was added. The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 1M KHS0₄ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo to give a colourless oil identified as 3-[Λ/-(tert-butyloxycarbonyl)-L- glutamyljthiazolidine (3.0g, 9.4mmol, 97%).

10C. S-I/V'-fteft-Butyloxycarbonylϊ-Λ ^a^-dichlorobenzylJ-L-glutaminyl]- thiazolidine

3-[Λ/-(fert-Butyloxycarbonyl)-L-glutamyl]thiazolidine (200mg, 0.63mmol) was dissolved in CH₂CI₂/DMF (9:1, 10ml). To this solution at 0°C was added 1-hydroxybenzotriazole hydrate (119mg, 0.76mmol), water-soluble carbodiimide (163mg, 0.88mmol), 3,4- dichlorobenzylamine (111mg, 0.83mmol) and triethylamine(126mg, 1.26mmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHSO₄ (2 x 20ml), sat. NaHC0₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo to give a yellow oil. The residue was purified by flash chromatography on silica gel (eluant: ethyl acetate) to give a colourless oil identified as 3-[/\T-(terf-butyloxycarbonyl)-AT-(3,4-dichlorobenzyl)- L-glutaminyl]thiazolidine (295mg, 0.62mmol, 98%).

10D. 3-[Λ ^α-(Acetoxymethoxycarbonyl)-ΛT^D-(3,4-dichlorobenzyl)-L-glutaminyl]- thiazolidine

3-[tV^σ-(fert^,-Butyloxycarbonyl)-Λ/^ω-(3,4-dichlorobenzyl)-L-glutaminyl]thiazolidine (150mg, 0.32mmol) was dissolved in 4M HCI/dioxan (20ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and acetoxymethyl p-nitrophenyl carbonate (95mg, 0.35mmol; prepared according to Alexander ef al., J. Med. Chem. 31 , 318, 1988) and triethylamine (64mg, 0.64mmol) were added. The solution was stirred at room temperature for 18 hours then evaporated in vacuo. The residue taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0 ) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: ethyl acetate) to give a white solid identified as 3-[Λ/ - (acetoxymethoxycarbonyl)-ΛT-(3,4-dichlorobenzyl)-L-glutaminyl]thiazolidine (88mg, 0.18mmol, 56%).

[M+H]⁺ = 492.0 H NMR (CDCI₃): δ 1.44-1.46 (3H,m), 1.63-1.99 (3H,br m), 1.99-2.04 (4H,m), 2.98-3.06 (2H,m), 3.46-3.48 (2H,m), 3.50-3.80 (2H m), 4.47-4.56 (3H,m), 5.81-5.91 (1 H,m), 6.74- 6.75 (1H,m), 7.24-7.33 (1H,m), 8.24-8.25 (1H,m), 8.69-8.71 (1H,m) ppm.

EXAMPLE 11 l-tW-tl'-Acetoxyethoxycarbony -Λ^-t∑-chloronicotinoyO-L-ornithinyπpyrrolidine

11 A. 1-[Λ/^ω-(Benzyloxycarbonyl)-Λ/^et-(tert-butyloxycarbonyl)-L- ornithinyl]pyrrolidine

/V^B-(Benzyloxycarbonyl)-Λ/^α-(ferf-butyloxycarbonyl)-L-ornithine (5.49g, 15mmol) was dissolved in CH₂CI₂/DMF (9:1 , 100ml). To this solution at 0°C were added 1-hydroxybenzotriazole hydrate (3.37g, 22mmol), water-soluble carbodiimide (3.46g, 18mmol), pyrrolidine (1.28g, 18mmol) and triethylamine (200mg, 20mmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (200ml). The solution was washed with 0.3M KHS0₄ (2 x 50ml), sat. NaHC0₃ (2 x 50ml), water (2 x 50ml) and brine (1 x 50ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 90% ethyl acetate, 10% pet. ether 60-80) to give a colourless oil identified as 1-[ΛT-(benzyloxycarbonyl)-/V^α-(ferf- butyloxycarbonyl)-L-ornithinyl]pyrrolidine (5.15g, 12.3mmol, 82%).

11B. l-J/^-ifeff-Butyloxycarbony -L-ornithinyllpyrrolidine

To a solution of 1-[/V^ω-(benzyloxycarbonyl)-/V^cl-(ferf-butyloxycarbonyl)-L-ornithinyl]- pyrrolidine (2.15g, 5.13mmol) in methanol (80ml) was added 10% Pd/C (400mg). The mixture was stirred under a hydrogen atmosphere for 2 hours then the catalyst was filtered off and washed with methanol (50ml). The combined filtrates were evaporated in vacuo to give an off white solid identified as 1-[Λ -(terf-butyloxycarbonyl)-L- omithinyljpyrrolidine (1.35g, 4.74mmol, 94%).

11C. l-t/V-ttert-Butyloxycarbony -Λ ^Σ-chloronicotinoy -L-ornithinyllpyrrolidine

1-[/\ -(fert-Butyloxycarbonyl)-L-ornithinyl]pyrrolidine (204mg, 0.72mmol) was dissolved in CH₂CI₂ (20ml). To this solution was added 2-chloronicotinoyl chloride (130mg, 0.74mmol) and triethylamine (200mg, 2.0mmol). The mixture was stirred for 18h at 0°C to room temperature then the solvent was removed in vacuo and the residue was taken up in ethyl acetate (70ml). The solution was washed with 0.3M KHS0₄ (2 x 20ml), sat. NaHC0₃ (2 x 20ml), water (2 x 20ml) and brine (1 x 20ml), dried (Na₂S0₄) and evaporated in vacuo. The residue was purified by flash chromatography on silica gel (eluant: 10% methanol, 90% chloroform) to give a sticky white solid identified as 1- [W^α-(fert-butyloxycarbonyl)-/V^ω-(2-chloronicotinoyl)-L-ornithinyl]pyrrolidine (236mg,

0.56mmol, 78%).

11D. 1-[N^α-(1'-Acetoxyethoxycarbonyl)-AT-(2-chloronicotinoyl)-L-ornithinyl]- pyrrolidine

1-[A^a-(ferf-Butyloxycarbonyl)-/\T-(2-chloronicotinoyl)-L-ornithinyl]pyrrolidine (206mg, 0.49mmol) was dissolved in 4M HCI/dioxan (20ml). The mixture was stirred for 1 hour at room temperature then the solvent was removed in vacuo. The residue was dissolved in dichloromethane (25ml) and α-acetoxyethyl p-nitrophenyl carbonate (140mg, 0.52 mmol; prepared according to Alexander ef al., J. Med. Chem. 31 , 318, 1988) and triethylamine (40mg, 0.4mmol) were added. The solution was stirred at room temperature for 18 hours then evaporated in vacuo. The residue was taken up in ethyl acetate (70ml). The solution was washed with sat NaHC0₃, water and brine, dried (Na₂S0₄) and evaporated. The residue was purified by flash chromatography on silica gel (eluant: 92% chloroform, 8% methanol) to give a white solid identified as 1- [N^α-(1'-acetoxyethoxycarbonyl)-ΛT-(2-chloronicotinoyl)-L-ornithinyl]pyrrolidine (127mg, 0.28mmol, 57%).

[M+H]⁺ = 455.1

¹H NMR (CDCI₃): δ 1.42-1.49 (3H,m), 1.83-1.95 (8H,m), 2.02 (3H,d,J=1.5Hz), 3.32-3.71 (6H,m), 4.45-4.47 (1 H,m), 5.75-5.85 (1 H,m), 6.72-6.77 (2H.m), 7.27-7.33 (1H,m), 7.97- 8.06 (1H,m), 8.40-8.43 (1H,m) ppm.

Claims

1 A compound according to general formula 1

or a pharmaceutically acceptable salt thereof, wherein:

R¹ is H or CN,

R² is selected from CH₂R⁵, CH₂CH₂R⁵ and C(R³)(R⁴)-X²-(CH₂)_aR⁵,

R³ and R⁴ are each independently selected from H and Me;

R⁵ is selected from C0N(R⁶)(R⁷), N(R⁸)C(=0)R⁹, N(R⁸)C(=S)R⁹, N(R⁸)S0₂R¹⁰ and N(R⁸)R¹⁰;

R^β and R⁷ are each independently R¹¹(CH₂)_b or together they are -(CH₂)₂-Z-(CH₂)₂- or -CH₂-o-C₆H₄-Z-CH₂-;

R⁸ is H or Me;

R⁹ is selected from R ¹(CH₂)_b, R¹¹(CH₂)_bO and N(R⁶)(R⁷);

R¹⁰ is R¹¹(CH₂)_b;

R¹¹ is selected from H, alkyl, optionally substituted aryl, optionally substituted aroyl, optionally substituted arylsulphonyl and optionally substituted heteroaryl;

R¹² is selected from H₂NCH(R¹³)CO, H₂NCH(R¹⁴)CONHCH(R¹⁵)CO, C(R¹⁶)=C(R¹⁷)C0R¹⁸ and R¹⁹OCO;

R¹³, R¹⁴ and R¹⁵ are selected from the side chains of the proteinaceous amino acids;

R ⁶ is selected from H, lower alkyl (Ci - C₆) and phenyl;

R¹⁷ is selected from H and lower alkyl (Ci - C₆);

R¹⁸ is selected from H, lower alkyl (Ci - C₆), OH, 0-(lower alkyl (Ci - C₆)) and phenyl;

R¹⁹ is selected from lower alkyl (Ci - C₆), optionally substituted phenyl and R²⁰C(=O)OC(R²¹)(R²²);

R²⁰, R²¹ and R²² are each independently selected from H and lower alkyl (d - C₆);

Z is selected from a covalent bond, -(CH₂)_C-, -0-, -SO_d- and -N(R¹⁰)-;

X¹ is S or CH₂,

X² is O, S or CH₂;

a is 1 , 2 or 3

b is 0 - 3;

c is 1 or 2; and

d is 0 - 2

A compound according to Claim 1 wherein R¹ is H.

A compound according to Claim 1 wherein R¹ is CN.

A compound according to any of Claims 1 to 3 wherein R² is selected from

CH₂CH₂R⁵ and C(R³)(R⁴)-X²-(CH₂)_aR^s. 5 A compound according to claim 2 or claim 3 wherein X¹ is CH₂.

6. A compound according to claim 1 or claim 2 wherein X¹ is S.

7 A compound according to Claim 4 wherein R³ and R⁴ are both H, X² is CH₂ and a is 1 or 2.

8 A compound according to Claim 7 wherein R² is selected from CH₂CH₂CH₂R⁵ and CH₂CH₂CH₂CH₂R⁵.

9 A compound according to any of Claims 1 to 8 wherein R⁵ is CON(R⁶)(R⁷).

10 A compound according to any of Claims 1 to 4 and 6 to 8 wherein R⁵ is selected from N(R⁸)C(=O)R⁹, N(R⁸)C(=S)R⁹, N(R⁸)S0₂R¹° and N(R⁸)R¹⁰.

11 A compound according to claim 5 wherein R⁵ is selected from CON(R⁶)(R⁷),

N(R⁸)C(=O)R⁹, N(R⁸)C(=S)R⁹ and N(R⁸)R¹⁰.

12 A compound according to any of Claims 1 to 11 wherein R¹² is selected from

H₂NCH(R¹³)CO and H₂NCH(R¹⁴)CONHCH(R¹⁵)CO.

13 A compound according to any of Claims 1 to 11 wherein R¹² is R¹⁹OCO.

14 A pharmaceutical composition comprising a compound according to any of

Claims 1 to 13.

15 The use for a compound according to any of Claims 1 to 13, which is as a component in the preparation of a pharmaceutical composition.

16 A method of treatment of hyperglycaemia which comprises the administration to an individual in need of such treatment of an effective amount of a compound according to any of Claims 1 to 13.

17 A compound or pharmaceutical composition according to any of Claims 1 to

14, a use according to claim 15 or 21 or a method according to any of claims claim 16 or 18 to 20, with the proviso that R¹⁹ is not t-butyl. A method of treatment of a disease or medical condition in a human or animal which comprises the administration to an individual in need of such treatment of an effective amount of a compound according to general formula 1

or a pharmaceutically acceptable salt thereof, wherein:

R¹ is H or CN,

R³ and R⁴ are each independently selected from H and Me;

R⁵ is selected from CON(R⁶)(R⁷), N(R⁸)C(=0)R⁹, N(R⁸)C(=S)R⁹, N(R⁸)S0₂R ° and N(R⁸)R¹⁰;

R⁶ and R⁷ are each independently R¹¹(CH₂)_b or together they are -(CH₂)₂-Z-(CH₂)₂- or -CH₂-o-C₆H₄-Z-CH₂-;

R⁸ is H or Me;

R⁹ is selected from R¹¹(CH₂)_b, R¹¹(CH₂)_bO and N(R⁶)(R⁷);

R¹⁰ is R¹¹(CH₂)_b;

R¹² is selected from H₂NCH(R¹³)CO, H₂NCH(R¹⁴)CONHCH(R¹⁵)CO, C(R¹⁶)=C(R¹⁷)COR¹⁸ and R¹⁹OCO; R¹³, R¹⁴ and R¹⁵ are selected from the side chains of the proteinaceous amino acids;

R¹⁶ is selected from H, lower alkyl (d - C₆) and phenyl;

R¹⁷ is selected from H and lower alkyl (Ci - C₆);

R¹⁸ is selected from H, lower alkyl (d - C₆), OH, 0-(lower alkyl (d - C₆)) and phenyl;

R²⁰, R²¹ and R²² are each independently selected from H and lower alkyl (Ci - C_β);

Z is selected from a covalent bond, -(CH₂)_C-, -O-, -SO_d- and -N(R¹⁰)-;

X¹ is S or CH₂,

X² is O, S or CH₂;

a is 1 , 2 or 3

b is 0 - 3; c is 1 or 2; and d is 0 - 2 A method according to claim 18 in which the disease or medical condition is impaired glucose tolerance, type II diabetes or hyperglycaemia.

A method according to claim 18 in which the disease or medical condition is due to a DP-IV mediated process. The use for a compound according to any of Claims 1 to 13, which is as a DP-

IV inhibitor, or as a prodrug for a DP-IV inhibitor.