Background

DP-IV (EC 3.4.14.5) is a membrane-bound serine protease first identified in rat kidney by its ability to cleave dipeptides from the N-terminus of certain peptides (Hopsu-Havu, V.K. and Glenner, G.G., Histochemie, 1966, 7, 197). The dipeptides must be of the type X-Pro or X- Ala where X = any amino acid. X-Proline is more efficiently cleaved than X- Ala.

DP-IV is widely distributed in mammalian tissues and is found in great abundance in the Mdney, intestinal epithelium and placenta (Yaron, A. and Naider, F., Critical Reviews in Biochem. Mol. Biol. 1993, 28 (1), 31). In the human immune system the enzyme is expressed almost exclusively by activated T-lymphocytes of the CD4 ⁺ type where the enzyme has been shown to be synonymous with the cell-surface antigen CD26.

The exact role of DP-IV in human physiology is not completely understood but recent research has shown that the enzyme clearly has a major role in human physiology and pathophysiology, eg.

(a) The immune response: DP-IV expression is increased in T-cεlls upon mitogenic or antigenic stimulation (Mattem, T. et al., Scand. J. Immunol. 1991, 33, 737). It has been reported that inhibitors of DP-IV and antibodies to DP-IV suppress the proliferation of mitogen- and antigen-stimulated T-cells in a dose-dependant manner (Schon, E. et al., Biol. Chem. Hoppe-Seyler, 1991, 372, 305 and refs. within).

Various other functions of T-lymphocytes such as cytokine production, IL-2 mediated cell proliferation and B-cell helper activity have been shown to be dependant on DP-TV activity (Schδn, E. et al., Scand. J. Immunol. 1989, 29, 127). Recently, DP-IV inhibitors based on boroproline where reported (Flentke, G.R. et al., Proc. Natl. Acad. Sci. USA, 1991, 8S, 1556) which, although unstable, were effective in inhibiting antigen-induced lymphocyte proliferation and IL-2 production in murine CD4 ⁺ T-helper cells. Such boronic acid inhibitors have been shown to have an effect in vivo in mice causing suppression of antibody production induced by immune challenge (Kubota, T. et al., Clin. Exp. Immunol. 1992, 89, 192). Other recent papers also provide evidence for the involvement of DP-IV in the immune response (eg. Tanaka, T. et al., Proc. Natl. Acad. Sci. NY, 1993, 90, 4586; Hegen, M. et al., Cell Immun. 1993, 146, 249; Subramanyan, M. et al., J. Immunol. 1993, 150, 2544).

- 9

The importance of DP-TV is attributed by some investigators to its cell-surface association with the transmembrane phosphatase CD45 (Torimoto, Y. et al., J. Immunol. 1991, 147, 2514). The CD45 - DP-IV association is possibly disrupted by DP-TV inhibitors or non-active site ligands. CD45 is known to be an integral component of T-cell signalling.

(b) Recently, a press release from the Pasteur Institute in Paris (and subsequently a presentation by A.G. Hovanessian at the 8th Cent. Gardes Meeting, Paris, 25-27th October 1993) reported that DP-TV was essential for the penetration and infectivity of HTV-1 and HTV-2 viruses in CD4 ⁺ T-cells. The French group claimed that DP-TV interacted with and may have cleaved the V3 loop of the gpl20 envelope giyco-protein of the virus. They also reported that inhibitors or antibodies to DP-TV successfully prevented entry of the virus into cells. It was known previously that there is a selective decrease of CD26 expression in T-cells from HIV-1 infected individuals (Valle-Blazquez, M. et al., J. Immunol. 1992, M9, 3073), and that HTV-1 Tat protein binds to DP-TV (Subramanyam, M. et al., J. Immunol. 1993, 150, 2544).

(c) It has been shown recently that lung endothelial DP-TV is an adhesion molecule for lung-metastatic rat breast and prostate carcinoma cells (Johnson, R.C. et al., J. Cell. Biol. 1993, 121, 1423). DP-IV is known to bind to fibronectin and some metastatic tumour cells are known to carry large amounts of fibronectin on their surface.

(d) DP-TV has been shown to associate with the enzyme adenosine deaminase (ADA) on the surface of T-cells (Kameoka, J. et al., Science, 1993, 261, 466). ADA deficiency causes severe combined immunodeficiency disease (SOD) in humans. This ADA-CD26 interaction may provide clues to the pathophysiology of SOD.

(e) High levels of DP-TV expression have been found in human skin fibroblast cells from patients with psoriasis, rheumatoid arthritis (RA) and lichen planus (Raynaud, F. et al., /. Cell. Physiol. 1992, 151, 378).

(f) High DP-TV activity has been found in tissue homogenates from patients with benign prostate hypertrophy and in prostatosomes. These are prostate derived organelles important for the enhancement of speim forward motility (Vanhoof, G. et al., Eur. J. Clin. Chem. Clin. Biochem. 1992, 30, 333).

(g) DP-TV has been shown to be responsible for the degradation and inactivation of circulating peptides with penultimate proline or alanine at the N-terminus, eg. substance P, growth hormone releasing factor and members of the glucagon/vasoactive intestinal peptide family (Menthein, R. et al., Eur. J. Biochem. 1993, 214. 829).

(h) Raised levels of DP-IV have been observed in the gingiva of patients with periodontitis (Cox, S.W. et al., Arch. Oral. Biol. 1992, 37, 167).

(i) There are also a number of other reports of raised (or sometimes lowered) levels of DP-TV in various pathological conditions.

It follows from the above that potent inhibitors of DP-IV may be useful as drugs for the treatment of human disease. Such inhibitors could be useful as:

(a) Immunosuppressants, eg. in organ transplantation; cytokine release suppressants eg. in various autoimmune diseases such as inflammatory bowel disease, multiple sclerosis, RA.

(b) Drugs for the prevention of HIV entry into T-cells and therefore useful in the prophylaxis and treatment of AIDS.

(c) Drugs for the prevention of metastases, particularly of breast and prostate tumours to the lungs.

(d) Agents to treat dermatological diseases, eg. psoriasis, lichen planus.

(e) Drugs to suppress sperm motility and therefore act as male contraceptive agents.

(f) Agents beneficial in benign prostate hypertrophy.

Inhibitors of DP-IV

The only competitive inhibitors of DP-TV enzyme activity reported so far are the unstable boronic acids (ty 30 - 90 min at pH 7) mentioned above. (Bachovchin et al., WO 91/16339, October 1991) having Ki values in the nanomolar range for DP-TV, and simple amino-acid pyrrolidides or thiazolides (Neubert et al., DD 296 075 A5, November 1991) which have only modest potency (K; > 0.1 μM). Amino-acyl proline aldehydes claimed in the same German patent cannot be synthesised due to a facile intramolecular condensation of the N-terminal amino group with the aldehyde function.

We now disclose highly potent competitive inhibitors of DP-IV (with K _; values in the 10" ⁶ - 10 ^"10 range) which are also chemically stable (ti > 24 h). They fall into three broad groups of compounds (Groups I, II and III).

GROUP I

These are molecules designed to bind tightly in the active site of DP-TV and to inhibit its proteolytic activity without interfering with attachment of any accessory ligands which may bind to the surface of DP-IV (i.e. not at its active site). Such Group I compounds could be useful as immunosuppressants; anti-HIV infectivity agents; agents to suppress release of certain cytokines (eg. IL-2, IL-6, γ-INF) from activated T-cells. The boronic acids and pyrrolidides referred to earlier also fall into this category.

GROUP II

These are evolved from Group I compounds; however they contain long-chain extensions to the side-chains of the amino-acid defined as A in the general structure. The resulting compounds bind tightly to the active-site of DP-IV but the long-chain extensions protrude from the enzyme active site and serve to prevent the attachment of any other ligand which may bind to the surface of DP-IV. Such compounds could have the same uses as Group I compounds but in addition could block the interaction of DP-IV with (i) CD45 (ii) the gp 120 V3 loop of HIV- 1 (iii) tumour cell surface fibronectin (iv) any other ligand important for T-cell activation, virus entry into T-cells or tumour cell adhesion.

GROUP in

This group comprises novel dimers in which two active-site directed inhibitors of DP-IV are linked via the side-chains of their amino-acid residues designated A in the general structure by a long chain. Such dimers can inhibit two molecules of DP-IV concurrently and also prevent accessory ligands binding to the surface of DP-IV. These dimers would have the same uses as Group II compounds but may be more effective.

The invention provides inhibitors of DP-IV mediated processes, the inhibitors being of general formula:

A-B (Groups I and II) or (Group HI)

where B is

wer alkyl (C _x to C _g );

A is attached to Y;

-Y = -N, -CH or =C (when the -CO group of A is replaced with CH= or CF=);

R = H, CN, CHO, B(OH) ₂ , C≡C-R ₇ , or CH=N-R ₈ ;

R ₇ = H, F, lower alkyl & to C ₆ ), CN, NO ₂ , Ol^, CO ₂ R ₉ or COR ₉ ;

R ₈ = Ph, OH, ORg, OCOR^ or OBn;

R _g = lower alkyl ( - C ₆ ); and either ω or both e's may be absent.

The structure of A is dependent on the nature of R in moiety B and on the nature of the group to which the resulting compound belongs.

Group I Compounds

(a) R = H

A is an α-amino-acyl group derived from an α-amino-acid bearing a cycloaliphatic side-chain (e.g. C ₄ to C ₁₀ , mono or bicyclic) whose ring may contain one or more heteroatoms e.g. L-cyclohexylglycine, L-cyclopentylglycine, L-decahydro- naphthylglycine, L-piperidylglycine;

or

A is a β-amino-acyl group of general formula

where p = 1 - 6 and the ring may also contain _{one or} more heteroatoms replacing CH ₂ unit(s).

Both α and β-amino acyl groups in (a) above may contain unsaturation in their rings

and also may contain one or more heteroatoms.

(b) R = CN: C≡C-R^ or CH=N-R<,

A is as defined in (a) above but in addition may be derived from any L-α-amino acid bearing a lipophilic side-chain, eg. lie.

(c) R = CHO or B(OH)-,

A is a β-amino-acyl group as defined in (a) above. The resulting A-B compounds are stable, unlike α-aminoacyl derivatives of the same type which undergo a facile intramolecular cyclisation. In compounds (c) B(OH) ₂ may be present as a boronate ester eg.

these being labile in water giving the free boronic acids.

Group II Compounds

Where R = H, CN, C≡C-R ₇ or CH=N-R ₈ , A is an α-amino acid derivative whose side-chain carries a functional group which is derivatised to produce a long chain terminating in various groups R ₃ . A may be of the following three types of structure:

where a = 1 - 5; D = G-(CH ₂ ) _b -(R ₄ ) _q -R ₃ ; G = O, NH, or NMe; b = 0-12; q = 0-5;

D ¹ = D with G ≠ O;

R ₄ = Z-NH-(CH ₂ ) _C - or NH-Z-(CΑ- _C - where c = 1-12 and Z = CO, CH ₂ or SO ₂ ; and

R ₃ = CO ₂ H or ester [e.g. any lower alkyl, fluoroalkyl or cycloalkyl (C _j to C ₈ ), or aromatic or heteroaromatic (5 or 6-membered rings, mono- or bicylic) ester] thereof; CONH ₂ ; CONHNH ₂ ; CONR ₅ R ₆ ; CONHNR ₅ R ₆ ; PO ₃ H (or ester thereof e.g. as defined under CO ₂ H); SO ₃ H; SO ₂ NH ₂ ; SO ₂ NR ₅ R ₆ ; OH; OR ₅ ; aryl or heteroaryl (e.g. 5 or 6-membered rings, monocyclic or bicyclic) [including substituted aryl or heteroaryl with substituents preferably chosen from F, Cl, I, Br, OH, OR ₅ , NO ₂ , SO ₃ H, SO ₂ NH ₂ , SO ₂ NR ₅ R ₆ , NH ₂ , NR ₅ R ₆ , CO ₂ R ₅ , CF ₃ , CN, CONH ₂ , CONR ₅ R ₆ , NHCO ₂ R ₅ , CH(:NR ₅ )NR ₅ R ₆ ,

NH-CH(:NR ₅ )NR ₅ R ₆ and R ₅ ]; NH ₂ ; NR ₅ R ₆ ; NHCO ₂ R ₅ ; NHSO ₂ NR ₅ R ₆ ; NHCOR5; NH-SO ₂ R ₅ ; NH-CH(:NR ₅ )NR ₅ R ₆ ; NHCONR ₅ R ₆ ; sugar (which may be attached via an ether or a glycosidic bond); CO-aminosugar (attached via the -NH ₂ ) eg. glucosamine or galactosamine; NHCO-aminosugar, or NHCS-aminosugar. In the above definition of R ₃ "sugar" refers to any carbohydrate or oligosaccharide, and R5 and R _$ are independently selected from H and alkyl, fluoroalkyl and cycloalkyl groups (of up to 8 atoms), aryl, heteroaryl and alkylheteroaryl groups (of up to 11 atoms) or R ₅ and R _$ together comprise a chain and (C ₃ to C ₈ ).

where R ¹ = H, Me; the ring may also contain more heteroatoms;

E = J-(CH* ₂ ) _b -(R ₄ ) _q -R ₃ ; J = CO, CH ₂ or SO ₂ ; and a, b, q, R ₃ and R ₄ as defined under (i)

where R ² = H or Me; the ring may also contain one or more heteroatoms;

L = (CH ₂ ) _d -[CO] _r -(CH ₂ ) _b -(R ₄ ) _q -R ₃ or (CH ₂ ) _e -NR ¹ -(CH ₂ ) _b -(R ₄ ) _q -R ₃ ; r = 0 or 1; d = 0 - 4; e = 2 - 4; and b, q, R ₃ and R ₄ as defined under (i).

Group m

Group m compounds are defined by the general formula:

where ω = CH ₂ , 0, NH, CO, S, SO ₂ , Ph or NMe and, independently, € = CH ₂ , O, NH, CO, S, SO ₂ , Ph or NMe.

These compounds are symmetrical dimers. They may have any B structure as defined previously. A may be chosen from any group II structure [(i), (ii) or (iii)], but in this case the terminal group R ₃ in each A residue is deleted and replaced with a shared symmetrical group [e-ω-€] which connects the two halves of the dimer, ω may be absent, in which case both €'s are joined together to constitute the chain linking the two A-B moieties; alternatively both e's may be absent in which case ω solely joins the two A-B moieties .

The structure of e-ω-€ must of course be chemically feasible eg. NH-CO-NH, CO-NH-CO-, SO ₂ -NMe-SO ₂ ; it will be obvious to those skilled in the art which structures are not feasible, eg. -NH-NH-NH-. A specific possible example is shown in Table 7.

In such compounds as described under Groups II and m certain -CH ₂ - groups present in the long chains could be replaced with known bioisosteres eg. -O- without affecting inhibitory or binding activity towards DP-TV. Also such groupings as -CONHCH ₂ CH ₂ NHCO if they occur could be replaced by eg.

/ \

-CO-N N-CO-

Further, for compounds in Groups I, II and in any amide bond connecting A and B or any amide in the side-chains of A (in Groups II and El) may be replaced by known bioisosteres of amides eg.

-CO-N replaced by -CO-C — . CF=C . -CH ₂ -N

\ \ ' \ ' \ '

See Table 8 for examples of such replacements.

Biochemistry

All compounds were tested in vitro against pure human DP-TV (purchased from M & E, Copenhagen, Denmark). Inhibition of DP-TV was determined using the fluorescent substrate Ala-Pro-AFC (K^ 0.8 μM) at three concentrations for each inhibitor. A typical assay (total volume 0.4 ml) comprised sodium Hepes 83.3 mM, EDTA 1.67 mM, BSA 1.5 mg ml" ¹ pH 7.8, DP-TV 25 μU ml ^"1 , inhibitor (in 10 mM acetate pH 4.0). The reaction was started by the addition of substrate and readings taken every 30 s for 7.5 min, excitation at 395 nm, emission 450 nm. K values were determined using Dixon plots.

Chemistry

152 Examples of compounds synthesised are shown in Tables 1 - 8 followed by schemes and experimental details for the preparation of different structural types. All final products were characterised by FAB mass spectrometry and purity assessed by reverse phase hplc; all intermediates were characterised by ^! H NMR.

Table 9 shows selected Kj values against DP-IV determined for inhibitors of different structural types.

Table 1

Examples of Group I (a)

Calculated FAB Mass

No. R π Formula Mol. Wt. spec. fM- H1+

CH, H C-nH NaC* 196.2 197.2

CH, H ^C 12 ^H 22 ^N 2° 210.2 211.2

CH ₂ H 1 C ₁₀ H2oN ₂ 0 184.2 185.2

CH ₂ H 1 C ₁₂ H ₂₀ N ₂ O 208.2 209.2

CH ₂ H 1 C ₁₁ H ₂₀ N ₂ O 196.1 197.2

Calculated FAB Mass

No. R n Formula

CH; H CιιH ₁₈ N ₂ 0 194.1 195.2

182.1 183.2

CH; H C .,H ₁₄ N ₂ 0 190.1 191.2

10 CH ₂ H 1 C ₁₃ H ₂₄ N ₂ 0 224.2 225.2 trans

Table 2

Examples of Group I (b)

Calculated FAB Mass

No. R ¹ R Formula Mol. Wt. spec. .M+H1+

11 H-lle CH; 1 H CN C^H^NgO 209.3 210.2

12 H-Lys(Z) CH; H CN C .gH^O, 358.2 359.2

CH; H CN C ₁₀ H ₁₅ N ₃ O 193.1 194.1

CH ₂ 1 H CN C ₉ H ₁₃ N ₃ OS 211.1 212.2

CH ₂ 1 H CN C ₉ H ₁₃ N ₃ OS 211.1 212.2

CH ₂ 1 H CN C ₁₃ H _2l N ₃ 0 235.2 236.3

CH ₂ 1 H CN C ₁₂ H ₁₉ N ₃ 0 221.2 222.2

Calculated FAB Mass

R ¹ R Formula

Mol. Wt. spec. [M+H1-*-

CH; 1 H CN CnH NgO 209.2 210.2

1 H CN C ₁₀ H ₁₇ N ₃ OS 227.1 228.1

1 CN H ^C 10 ^H .7 ^N 3 OS 227.1 228.1

1 H CN C ₁₂ H ₁₉ N ₃ OS 253.1 254.1

H-Lys(Z) 1 H CN C-* ₈ H ₂ 4N, ₃ s 376.2 377.2

H CN C . .H ₁₇ N ₃ OS 239.1 240.2

H-lle 1 H CN C ₁₀ H ₁₇ N ₃ O ₂ 211.1 212.2

H-lle CH ₂ 2 H CN C ₁₂ H ₂₁ N ₃ 0 223.2 224.2

H-lle S 2 H CN C^H^ - _j OS 241.1 242.1

H-lle S0 ₂ 1 H CN C ₁₀ H ₁₇ N ₃ O ₃ S 259.1 260.1

H-lle S ⁺ "'i O 1 H CN C ₁₀ H ₁₇ N ₃ O ₂ S 243.1 244.1

H-lle S ^* — 0 1 H CN C ₁₀ H ₁₇ N ₃ O ₂ S 243.1 244.2

Calculated FAB Mass A X π R ¹ R f-ormuia Mol. Wt. spec. [M+H1+

CH; 1 H CN C ₁₂ H ₁₉ N ₃ 0 221.2 222.2

CH; H CN C ₁₂ H ₁₉ N ₃ 0 221.2 222.2

CH, 1 H CN C ₁₂ H ₁₇ N ₃ 0 219.1 220.1

CH ₂ 1 H CN C ₁₂ H ₁₇ N ₃ 0 219.1 220.1

Calculated FAB Mass

R ¹ R Formula

Mol. Wt. spec. fM+H1+

CH; 1 H CN C ₁₂ H ₁₉ N,0 221.2 222.2

CH ₂ 1 H CN C ₁₂ H ₁₇ N ₃ 0 219.1 220.1

Table 3

Examples of Group I (c)

Calculated FAB Mass

No. R π Formula Mol. Wt. spec. \M+HV

CH; CHO 1 C ₁₂ H ₂₀ N ₂ O ₂ 224.2 225.2

CH, CHO 1 CιιH ₁₈ N ₂ 0 ₂ 210.2 211.2

CH, CHO 1 C _, .H ₁₈ N ₂ 0 ₂ 210.2 211.2

43 CH ₂ B ^* 1 C ₂₁ H ₃₅ BN ₂ 0 ₃ 374.3 375.1

44 J- >γ, ./ CH ₂ B ^* 1 C ₂₁ H ₃₃ BN ₂ 0 ₃ 372.3 373.3

O

Table 4

Examples of Group II (i)

Calculated FAB Mass No. n Q X m R Formula Mol. Wt. spec. [M+H1+

46 1 -C0NHCH ₂ C0 ₂ Bn CH ₂ 1 H C ₁₇ H ₂₃ N ₃ 0 ₄ 333.2 334.2

47 1 -CONHCH ₂ C0 ₂ H CH ₂ 1 H C ₁₀ H ₁₇ N ₃ O ₄ 243.1 244.2

48 1 -CONH(CH ₂ ) ₃ C0 ₂ H CH ₂ 1 H C ₁₂ H ₂₁ N ₃ 0 ₄ 271.2 272.2

49 1 -CONH(CH ₂ ) ₂ C0 ₂ Bπ CH ₂ 1 H C^H^N^ 347.2 348.2

50 1 -C0NH(CH ₂ ) ₂ C0 ₂ H CH ₂ 1 H C ₁₁ H ₁₉ N ₃ 0 ₄ 257.1 258.2

51 1 -CONH(CH ₂ ) ₅ C0 ₂ Bn CH ₂ 1 H C ₂₁ H ₃₁ N ₃ 0 ₄ 389.3 390.3

52 1 -C0NH(CH ₂ ) ₅ C0 ₂ H CH ₂ 1 H C^H^N^ 299.2 300.2

53 1 -CONH(CH ₂ ) ₃ C0 ₂ Bπ CH ₂ 1 H C ₁₉ H ₂₇ N ₃ 0 ₄ 361.2 362.2

54 2 -C0NHCH ₂ C0 ₂ Bn CH ₂ 1 H C ₁₈ H2 ₅ N ₃ θ ₄ 347.2 348.2

55 2 -CONHCH ₂ C0 ₂ H CH ₂ 1 H C ₁₁ H ₁₉ N ₃ 0 ₄ 257.1 258.1

56 2 -C0NH(CH ₂ ) ₂ C0 ₂ Bn CH ₂ 1 H C ₁₉ H ₂₇ N ₃ 0 ₄ 361.2 362.3

57 2 -C0NH(CH ₂ ) ₃ C0 ₂ Bn CH ₂ 1 H CgoHgg ^ 375.2 376.3

58 2 -CONH(CH ₂ ) ₃ C0 ₂ H CH ₂ 1 H C^H^ ^ 285.2 286.2

Calculated FAB Mass π Q X m R Formula Mol. Wt. spec. fM+H1+

2 -CONH(CH ₂ ) ₅ C0 ₂ Bπ CH ₂ 1 H C^H^N^ 403.3 404.3

2 -CONH(CH ₂ ) ₅ C0 ₂ H CH ₂ 1 H C ₁₅ H ₂₇ N ₃ 0 ₄ 313.2 314.2

2 -CONH(CH ₂ ) ₂ C0 ₂ H CH ₂ 1 H C ₁₂ H ₂₁ N ₃ 0 ₄ 271.2 272.2

2 -C0NH(CH ₂ ) ₇ C0 ₂ Bπ CH ₂ 1 H C ₂₄ H ₃₇ N ₃ 0 ₄ 431.3 432.4

2 -CONH(CH ₂ ) ₇ C0 ₂ H CH ₂ 1 H C ₁₇ H ₃₁ N ₃ 0 ₄ 341.3 342.5

2 -C0NH(CH ₂ ) ₇ C0NH- CH ₂ 1 H C ₂₉ H ₄₅ N ₅ 0 ₅ 531.3 532.3

(CH ₂ ) ₃ NHZ

2 -C0NH(CH ₂ ) ₆ C0NH- CH ₂ 1 H C ₂₉ H ₄₆ N4θ ₅ 530.4 531.2

(CH ₂ ) ₅ C0 ₂ Bn

2 -CONH(CH ₂ ) ₆ CONH- CH ₂ 1 H C^H^^Og 440.3 441.3

(CH ₂ ) ₅ C0 ₂ H

2 -CONH(CH ₂ ) ₇ CONH- CH ₂ 1 H C^H^N- _j Og 397.3 398.3

(CH ₂ ) ₃ NH ₂

2 -CONH(CH ₂ ) ₁₁ C0 ₂ Bn CH ₂ 1 H Ca^ ;^ 487.3 488.4

2 -CONHtCH^CO^ CH ₂ 1 H C ₂₁ H3gN ₃ θ4 397.3 398.3

2 -CONH(CH ₂ ) ₆ C0 ₂ Bn CH ₂ 1 H C^H^N^ 417.3 418.3

2 -CONH(CH ₂ ) ₆ C0 ₂ H CH ₂ 1 H C ₁₆ H ₂₉ N ₃ 0 ₄ 327.2 328.2

2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C^H^Fg^Og 394.2 395.3

Calculated FAB Mass o. n Q X m R Formula

Mol. Wt. spec. \M+ HI +

73 2 -C0NH(CH ₂ ) ₅ C0NH- CH ₂ 1 H C ₁₉ H ₂₉ F ₇ N ₄ 0 ₃ 494.2 495.2

CH ₂ (CF ₂ ) ₂ CF ₃

74 2 -C0NH(CH ₂ ) ₅ C0NH- CH ₂ 1 H C^H^N^ 412.3 413.2

(CH ₂ ) ₆ 0H

75 2 -C0NH(CH ₂ ) ₅ C0NH- CH ₂ 1 H C24H3aN4θ3 430.3 431.2

(CH ₂ ) ₃ P

76 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C^H^^Og 444.3 445.2

(CH ₂ ) ₄ Ph

77 2 -CONH(CH ₂ ) ₅ CON- CH ₂ 1 H C^H^^Og 424.3 425.3

( ⁿ Bu) ₂

78 2 -CONH(CH ₂ ) ₅ CON- CH ₂ 1 H C ₂₇ H ₅₂ N ₄ 0 ₃ 480.4 481.4

("Hx) ₂

79 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C^H^O- _j 402.3 403.4

CH ₂ Ph

80 2 -CONH(CH ₂ ) ₄ C0 ₂ Bπ CH ₂ 1 H C ₂₁ H ₃₁ N ₃ 0 ₄ 389.2 390.3

81 2 -C0NH(CH ₂ ) ₄ C0 ₂ H CH ₂ 1 H C ₁₄ H ₂₅ N ₃ θ4 299.2 300.3

82 2 -C0NH(CH ₂ ) ₅ C0NH- CH ₂ 1 H C ₁₇ H ₃₂ N ₄ 03 340.3 341.3

CH ₂ CH ₃

83 2 -C0NH(CH ₂ ) ₆ 0H CH ₂ 1 H C^H^NgOg 299.2 300.3

84 2 -C0NH(CH ₂ ) ₅ C0-1 -Pip CH ₂ 1 H CaoHg _β ^Og 380.3 381.4

85 2 -C0NH(CH ₂ ) ₅ C0NH ₂ CH ₂ 1 H C ₁₅ H ₂₈ N ₄ 0 ₃ 312.2 313.3

Calculated FAB Mass o. n Q X m R Formula Mol. Wt. spec TM+H1+

86 2 -C0NH(CH ₂ ) ₅ C0NH- CH ₂ 1 H C^H^Og 452.4 453.5

(CH ₂ ) ₉ CH ₃

_a _ . -CONH(CH ₂ ) ₅ CONH- _ru _. _{u r u} M _{O A} ^ - -

87 2 ² '° CH ₂ 1 H C22H ₄₂ N ₄ 0 ₃ 410.3 411.4

(CH ₂ ) ₆ CH ₃

88 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C^H^^Og 408.3 409.4

CH ₂ Ch

89 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C ₂₆ H ₄₁ N ₅ 0 ₅ 503.3 504.4

(CH ₂ ) ₃ NHZ

90 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C^HggNgOg 369.3 370.3

(CH ₂ ) ₃ NH ₂

91 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C _ιg Ha7N ₇ 0 ₃ 411.3 . 412.4

(CH ₂ ) ₃ -Gua

92 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C ₂₁ H ₃₂ N ₄ 0 ₆ S 468.2 469.2

Ph(4-S0 ₃ H)

93 2 -CONH(CH ₂ ) ₅ CONH-4- CH ₂ 1 H C^ ^NgOg 4S5.3 486.3

Pip(1-Bn)

94 2 -CONH(CH ₂ ) ₅ CONH- CH ₂ 1 H C-^^NgOg 395.3 396.3

4-Pip

95 2 -CONH(CH ₂ ) ₄ N(Z)- CH ₂ 1 H Cg^NgOe 595.3 596.3

(CH ₂ ) ₃ NHZ

96 2 -CONH(CH ₂ ) ₄ NH- CH ₂ 1 H C ₁₆ H ₃₃ N ₅ 0 ₂ 327.2 328.2

(CH ₂ ) ₃ NH ₂

Calculated FAB Mass No. n Q X m R Formula

Mol. Wt. spec. FM+H1+

97 2 -C0NH(CH ₂ ) ₅ C0 ₂ Bπ CH ₂ 1 CN C23H32N ₄ 04 428.3 429.3

98 3 -C0NH(CH ₂ ) ₆ C0NH- CH ₂ 1 H CgoH^Og 544.4 545.2

(CH ₂ ) ₅ C0 ₂ Bπ

99 3 -CONH(CH ₂ ) ₆ CONH- CH ₂ 1 H 0^42^0,5 454.3 455.3

(CH ₂ ) ₅ C0 ₂ H

100 3 -CONH(CH ₂ ) ₅ C0 ₂ Bn CH ₂ 1 H Ca^l^ 417.3 418.2

101 3 -CONH(CH ₂ ) ₅ C0 ₂ H CH ₂ 1 H C ₁₆ H2gN ₃ θ4 327.2 328.2

102 2 -S0 ₂ NH(CH ₂ ) ₅ C0 ₂ H CH ₂ 1 H C^H^NgOgS 349.2 350.2

103 2 -CONH(CH ₂ ) ₈ NH-G ^* CH ₂ 1 H C24H4 ₅ N507S 547.4 548.5

Table 5

Examples of Group II (ii)

Calculated FAB Mass

No. n Q m R Formula Mol. Wt. spec. TM+H1+

104 1 -CO(CH ₂ ) ₆ C0 ₂ H CH ₂ H C ₁₅ H ₂₇ N ₃ 0 ₄ 313.2 314.3

105 1 -CO(CH ₂ ) ₆ C0 ₂ Bn CH ₂ H C ₂₂ H ₃₃ N ₃ 0 ₄ 403.3 404.3

106 3 -CO(CH ₂ ) ₄ C0 ₂ H CH ₂ H Cι ₅ H ₂₇ N ₃ 0 ₄ 313.2 314.3

107 3 -CO(CH ₂ ) ₄ C0 ₂ Me CH ₂ H C^H^N- 327.2 328.3

108 4 -CO(CH ₂ ) ₅ NH ₂ CH ₂ H C- _|g H ₃₂ N ₄ 0 ₂ 312.3 313.3

109 4 -CO(CH ₂ ) ₃ NH ₂ CH ₂ H C ₁₄ H ₂₈ N ₄ 0 ₂ 284.2 285.2

110 4 -CO(CH ₂ ) ₃ NHS0 ₂ Pfp CH ₂ H C^H^FgN^S 514.2 515.2

111 4 -CO(CH ₂ ) ₃ NHCOPfp CH ₂ H C ₂₁ H ₂₇ F ₅ N,0^3 478.2 479.2

112 4 -CO(CH ₂ ) ₃ NHS0 ₂ - CH ₂ H Ci6H29F ₃ N ₄ 0 ₄ S 430.2 431.3

113 4 -COfCH^NHCO- CH ₂ H C^HgaNgOg 657.5 658.6

(CH ₂ ) ₆ NHZ

114 4 -COfCH^NH- CH ₂ H ^C 29 ^H 57N5O3 523.4 524.4

CO(CH ₂ ) ₆ NH ₂

Calculated FAB Mass

No. _π Q X m R Formula Mol. Wt. spec. fM+HI÷

115 4 -CO(CH ₂ ) ₅ NHCO- CH ₂ 1 H CagHgoNgOs 672.5 673.6

(CH ₂ ) ₅ NHCO(CH ₂ ) ₅ . NHZ

116 4 -CO(CH ₂ ) ₅ NHCO- CH ₂ 1 H CggH^N^ 538.4 539.4

(CH ₂ ) ₅ NHCO(CH ₂ ) ₅ -

NH ₂

117 4 -CO(CH ₂ ) ₃ C0 ₂ H CH ₂ 1 H C ₁₅ H ₂₇ N ₃ 0 ₄ 313.2 314.3

118 4 -CO(CH ₂ )3C0 ₂ Bn CH ₂ 1 H 0^33^04 403.3 404.3

119 4 -CO(CH ₂ ) ₆ NH ₂ CH ₂ 1 H C ₁₇ H ₃₄ N ₄ 0 ₂ 326.3 327.3

120 4 -CO(CH ₂ ) ₇ NH ₂ CH ₂ 1 H C^HggN^ 340.3 341.3

121 4 -CO(CH ₂ ) ₁₆ Me CH ₂ 1 H C^H^O., 465.4 466.4

122 4 -CO(CH ₂ ) ₆ -Gua CH ₂ 1 H C ₁₈ H3sN ₆ 0 ₂ 368.3 369.3

123 4 -S0 ₂ (CH ₂ ) ₇ CH ₃ CH ₂ 1 H C ₁₈ H ₃₇ N ₃ 0 ₃ S 375.3 376.3

124 4 -C0(CH ₂ ) ₁₁ NH ₂ CH ₂ 1 H C22H44 402 396.4 397.4

125 4 -COCH ₂ NHZ CH ₂ 1 H O^Ha O, 390.2 391.3

126 4 -C0(CH ₂ ) ₂ NHZ CH ₂ 1 H C^H^N^ 404.2 405.3

127 4 -C0(CH ₂ ) ₃ NHZ CH ₂ 1 H C22H.J4N4O4 418.3 419.3

128 4 -C0(CH ₂ ) ₂ NH ₂ CH ₂ 1 H C ₁₂ H ₂ 4 ₄ 0 ₂ 256.2 257.2

Calculated FAB Mass

No. π Q m R Formula Mol. Wt. spec. [M+H1+

129 4 -C0(CH ₂ ) ₅ NHZ CH ₂ H C ₂₄ Ha ₈ N ₄ θ ₄ 446.3 447.4

130 4 -COCH ₂ -Gua CH H C ₁₃ H ₂₆ N ₆ 0 ₂ 298.2 299.3

131 4 -CO(CH ₂ ) ₂ NH ₂ CH ₂ H C ₁₃ H ₂₆ N ₄ 0 ₂ 270.2 271.3

132 4 -CO(CH ₂ ) ₂ -Gua CH ₂ H C .^NgO., 312.2 313.3

133 4 -CO(CH ₂ ) ₃ -Gua CH ₂ H Cι ₅ HaoN ₆ 0 ₂ 326.3 327.3

134 4 -CO(CH ₂ ) ₅ -Gua CH ₂ H Cι ₇ H ₃₄ N ₆ 0 ₂ 354.3 355.3

135 4 -CO(CH ₂ ) ₆ NH ₂ CH ₂ CN C* _|8 H3g _g 0 ₂ 351.3 352.4

136 4 -CO(CH ₂ ) ₇ NH ₂ CH ₂ CN C .9H35 5O2 365.3 366.3

Table 6

Examples of Group II (iii)

Calculated FAB Mass

No. R R1 π Y Formula Mol. Wt. spec. fM+H

137 H -0CH ₂ C0NH(CH ₂ ) ₅ - CH ₂ 1 H C ₁₅ H ₂₇ N ₃ 0 ₅ 329.2 330.3

C0 ₂ H

138 H -0CH ₂ C0NH(CH ₂ ) ₅ - CH ₂ 1 H 419.3 420.3

C0 ₂ Bn

139 H -0CH ₂ C0NH(CH ₂ ) ₄ - CH ₂ 1 H C ₂₁ H ₃₁ N ₃ 0 ₅ 405.2 406.3

C0 ₂ Bn

140 H -OCH ₂ CONH(CH ₂ ) ₄ - CH ₂ 1 H C^H^NgOg 315.2 316.3

C0 ₂ H

141 CH, -OCH, CH, 1 H C ₉ H ₁₈ N ₂ 0 ₂ 186.1 187.2

142 CH, -OC ₂ H ₅ CH ₂ 1 H C^H^N _j Os 200.1 201.2

143 CH ₃ -0(CH ₂ ) ₅ CH ₃ CH ₂ 1 H C ₁₄ H28N ₂ 0 ₂ 256.2 257.3

144 CH ₃ -0CH ₂ C0NH(CH ₂ ) ₅ - CH ₂ 1 H C23H35N3O5 433.3 434.3

C0 ₂ Bπ

145 CH ₃ -0CH ₂ C0NH(CH ₂ ) ₅ - CH ₂ 1 H 343.2 344.3

C0 ₂ H

Calculated FAB Mass No R R ¹ X n Y Formula Mol. Wt. spec. fM+ H1+

146 CH ₃ -OCH ₂ CONH(CH ₂ ) ₄ - CH ₂ 1 H C22H33N3O5 419.2 420.3

C0 ₂ Bn

147 CH ₃ -OCH ₂ CONH(CH ₂ ) ₄ - CH ₂ 1 H C ₁₅ H2 ₇ N ₃ 0 ₅ 329.2 330.3

C0 ₂ H

Table 7

Example of Group III

Table 8

Specific examples of compounds A-B, containing amide bond bioisosteres.

Calculated FAB Mass

No. A-B Formula Mol. Wt. spec. fM-f H1+

151 C ₁₂ H ₂₀ N ₂ 192.2 193.2

152 ^C 10 ^H 20 ^N 2 ^{S 200} - ^{1 201} - ²

Table 9

Selected K.- values against DP-IV.

No. K* (M)

Schematic Representations for General Preparation of all Classes of Compounds

Table 1

Compounds can be made by an adaption of the general route described by E. Schon et al., Biol. Chem. Hoppe-Seyler, 1991, 372, 305-311.

Table 2

(a) R: -CN

X = S mCPBA

(O) _v

Boc-A-N .

CN

H ⁺

y = l, 2

X

DMP Boc-A-N O

CH ₂ C1 ₂

H

(I)

.OR ¹

(c) R: CH=N ^'

r ^x )

(ID For R ¹ = -Ac

(R ^l =H)

_HA _r t

•_≡C-R

Table 3

Prepared by method of: W.W. Bachovchin et al.,

(a) J. Biol. Chem., 1990, 265, 3738-3743.

H

(b) R = CHO (I) H-A-N r ^x .

^CHO

Table 4 (W, P = Protecting groups; P ¹ , P ² = Groups as described in corresponding tables)

(a) R = CN

(i) remove P

(ii) HONSu, WSCD

(IV) complete synthesis as above

(IV) was prepared via method of G. Luisi et al., Tet. Lett., 1993, 34, 2391-2392. (c) For R = H, modify above procedure as described for Table 1 examples.

Table 5

(a) R = CN

H +

(b) R = H, modify above procedure as described for Table 1 examples.

Table 6

Use method described for Table 5 examples for preparation of (VI) from (V)

(i) NaH (ii) R* - Br (iii) H ⁺

Y = H, CN, -C=NPh, -C=NOR ¹ , -C≡CR ²

Table 7

Standard coupling, dehydration and deprotection sequence similar to above schemes.

(in)

0.5 molar equivalent H ₂ N(CH ₂ ) _m NH ₂

(i) POCl ₃ , pyridine (ii) H ⁺

Table 8

Toluene,

(b) reflux

Thioamides were prepared by the method described by K. Clausen et al. Tetrahedron, 1981, 37, 3635-3639. Other amide bioisosteres can be prepared from literature precedent. (A.F. Spatola in "Chemistry and Biochemistry of Amino Acids, Peptides and Proteins", Vol. IE, B. Weinstein Ed., Marcel Dekker, New York, 1983, p. 267).

Experimental Details for Specific Examples

EXAMPLE 1

2-(S)-Cyano-l-isoleucylpyrτolidine (11)

Di-isopropylethylamine was added to a solution of H-ProNH ₂ . HCl (225 mg, 1.50 mmol) in dry CH ₂ C1 ₂ (15 cm ³ ) until the pH was adjusted to 9. BocIleONSu was added in one portion and the mixture stirred for 16 h, under a nitrogen atmosphere. The solvent was evaporated and the residue treated in the standard way, i.e. the residue was partitioned between ethyl acetate (60 cm ³ ) and 0.3 N KHSO ₄ solution (10 cm ³ ). The organic layer was further washed with saturated NaCHO ₃ solution (10 cm ³ ), water (10 cm ³ ) and brine (5 cm ³ ). The solution was dried (Na ₂ SO ₄ ) and evaporated at reduced pressure. The crude product was passed down a short plug of silica gel, eluting with hexane:ethyl acetate, (10:90 to 0:100) to yield 301 mg (92%) of BocDeProNH ₂ as a colourless foam.

1H NMR (CDC1 ₃ ), δ (ppm); 6.90 (1H, br.s); 5.51 (1H, br.s); 5.18 (1H, d, J = 9.6 Hz); 4.62 (1H, dd, J = 2.6, 7.0 Hz); 4.29 (1H, dd, J = 8.4, 9.2 Hz); 3.79 - 3.58 (2H, m); 2.36 (1H, m); 2.09 - 1.57 (5H, m); 1.43 (9H, s); 1.17 (1H, m); 0.95 (3H, d, J = 6.6 Hz); 0.90 (3H, t, J = 7.3 Hz).

Imidazole (84 mg, 1.24 mmol) was added to a solution of BocIleProNH ₂ in dry pyridine (10 cm ³ ), under a nitrogen atmosphere. The solution was cooled to -35°C, before the dropwise addition of POCI ₃ (0.25 cm ³ , 2.48 mmol). The reaction was stirred at -30°C to -20°C for 60 min. The solution was then evaporated and the crude residue subjected to column chromatography (silica gel) to yield 180 mg (94%) of 2-(S)-cyano-l-[N-(t-butoxycarbonyl) isoleucyljpyrrolidine as a colourless oil.

*H NMR (CDC1 ₃ ), δ (ppm); 5.14 (1H, d, J = 9.2 Hz); 4.80 (1H, dd, J = 2.6, 7.1 Hz);

4.22 (1H, dd, J = 7.9, 9.1 Hz); 3.81 (1H, m), 3.71 (1H, m), 2.30 - 2.12 (4H, m); 1.75

(1H, m); 1.60 (1H, m); 1.42 (9H, s); 1.19 (1H, m); 0.97 (3H, d, J = 6.9 Hz); 0.91 (3H, t, J = 7.3 Hz).

¹³ C NMR (CDCI3), δ (ppm); 171.7, 155.6, 118.0, 79.6, 56.0, 46.5, 46.0, 37.8, 29.6,

28.1, 25.0, 24.2, 15.2, 10.9.

Deprotection was carried out by stirring with trifluoroacetic acid for 60 min. Evaporation and lyophilisation from water afforded 60 mg of 2-(S)-cyano-l-isoleucylpyrrolidine (11) as a white, fluffy solid.

FAB Mass Spec: Calculated 209.3, Found (M+H) ⁺ = 210.2. ^l ΕL NMR (D ₂ O), δ (ppm); 4.3 (1H, m); 3.64 (1H, d, J = 5.6 Hz); 3.16 (2H, m); 1.86 -

1.48 (5H, m); 0.98 (1H, m); 0.68 (1H, m); 0.51 (3H, d, J = 6.9 Hz); 0.38 (3H, t, J = 7.3

Hz).

¹³ NMR (D ₂ O), δ (ppm); 169.7, 119.7, 57.3, 48.6, 48.1, 36.9, 30.2, 25.8, 24.5, 15.4,

11.5.

EXAMPLE TWO

H-Glu[NH(CH ₂ ) ₇ CONH(CH ₂ ) ₃ NHZ]pyττOlidide (64)

Di-isopropylethylamine was added to a solution of BocGlu(OH)pyτrolidide (193 mg, 0.64 mmol) and PyBop (500 mg, 0.96 mmol) in CH ₂ C1 ₂ (6 cm ³ ) to adjust the pH of the mixture to 9. After stiiring for 5 min, a solution of benzyl 8-amino-octanoate (220 mg, 0.77 mmol) in CH ₂ C1 ₂ (5 cm ³ ) was added. The mixture was stirred at room temp for 16 h. The reaction was worked up in the standard procedure as described in example one. The crude residue was subjected to column chromatography (1% to 3% methanol in ethyl acetate) to obtain 344 mg (99%) of Bcκ:Glu[ πi(CH _:2 ) ₇ CO ₂ Bn]pyτrolidide as a colourless solid.

-Α NMR (CDC1 ₃ ), δ (ppm); 7.35 (5H, s); 6.63 (1H, br.t, J = 6.7 Hz); 5.65 (1H, d, J = 8.3 Hz); 5.11 (2H, s); 4.36 (1H, dt, J = 2.6, 8.9 Hz); 3.55 - 3.20 (6H, m); 2.34 (2H, t, J = 7.3 Hz); 2.26 (2H, dd, J = 5.6, 7.3 Hz); 2.11 - 1.48 (10H, m); 1.43 (9H, s); 1.32 - 1.27 (6H, m).

Hydrogen gas was bubbled through a solution of BocGlu(jNH(CH ) ₇ CO ₂ Bn]pyrrolidide (230 mg, 0.43 mmol) in ethyl acetate (10 cm ³ ), containing 10% palladium on charcoal (50 mg). After 90 min, the reaction vessel was flushed with nitrogen, the solution filtered through a pad of celite and the solvent evaporated to yield 187 mg (98%) of BocGlu[NH(CH ₂ ) ₇ CO ₂ H]pyrrolidide as a colourless oil.

Di-isopropylethylamine was added to a solution of BocGlu[NH(CH ₂ ) ₇ CO ₂ H]pyrrolidide (125 mg, 0.28 mmol) and PyBop (221 mg, 0.43 mmol) in CH ₂ C1 ₂ (10 cm ³ ) to adjust the pH of the solution to 9. After stirring for 5 min, a solution of ZNH(CH ₂ ) ₃ NH ₂ . HCl (90 mg, 0.37 mmol) and di-isopropylethylamine (38 mg, 0.37 mmol) was added in one portion. The solution was stirred for 18 h then treated in the standard procedure as described for example one. The crude residue was subjected to column chromatography (2% to 15% methanol in ethyl acetate) to afford 151 mg (85%) of BocGlu[NH(CH ₂ ) ₇ CONH(CH ₂ ) ₃ NHZ]pyτrolidide as a colourless oil.

*H NMR (CDC1 ₃ ), δ (ppm); 7.35 (5H, s); 6.60 (1H, br.t, J = 7.2 Hz); 6.14 (1H, br.t, J = 7.2 Hz); 5.63 (1H, d, J = 8.3 Hz); 5.39 (1H, br.t, J = 5.6 Hz); 5.10 (2H, s); 4.38 (1H, dt, J = 2.3, 9.2 Hz); 3.52 - 3.13 (10H, m); 2.26 (2H, t, J = 6.9 Hz); 2.17 (2H, t, J = 7.6 Hz); 1.98 - 1.48 (12H, m); 1.44 (9H, s); 1.38 - 1.23 (6H, m).

A solution of BocGlu|T πH(CH ₂ ) ₇ CONH((^ ₂ ) ₃ NHZ]pyrrolidide (14 mg, 0.022 mmol) in 4N HCl/dioxan was stirred for 45 min. The solvent was evaporated and the residue dissolved in water, filtered and lyophilised to yield 13 mg of H-Glu[NH(CH ₂ ) ₇ CONH(CH ₂ ) ₃ NHZ]pyrrolidide (64) as a colourless oil.

FAB Mass Spec: Calculated 531.3, Found (M+H) ⁺ = 532.3.

EXAMPLE THREE

H-Lys[CO(CH ₂ ) ₃ NHSO ₂ Pfp]pyτrolidide (110)

ZNH(CH ₂ ) ₃ CO ₂ NSu (570 mg, 1.7 mmol) was added in one portion to a solution of l-[N-(t-butoxycarbonyl)lysyl]pyrτolidine (745 mg, 2.2 mmol) in dry CH ₂ C1 ₂ . The pH was adjusted to 9 with di-isopropylethylamine and die mixture stirred for 60 min. The solvent was evaporated and the residue treated in the standard procedure as described for example one. Column chromatography (100% ethyl acetate to 15% methanol in ethyl acetate) afforded 620 mg (68%) of BocLys[CO(CH ₂ ) ₃ NHZ]pyτrolidide.

^l U NMR (CDC1 ₃ ), δ (ppm); 7.42 (5H, s); 6.31 (1H, br.t, J = 6.5 Hz); 5.58 (1H, d, J = 8.9 Hz); 5.39 (1H, br.t, J = 6.9 Hz); 5.17 (2H, s); 4.44 (1H, m); 3.72 - 3.20 (8H, m); 2.29 (2H, t, J = 7.3 Hz); 2.14 - 1.83 (8H, m); 1.78 - 1.41 (4H, m); 1.43 (9H, s).

Hydrogen gas was bubbled through a mixture of BocLys[CO(CH ₂ ) ₃ NHZ]pyrrolidide (620 mg, 1.16 mmol) and 10% palladium on charcoal in methanol (10 cm ³ ) containing one molecular equivalent of 2N HCl. After 60 min, the reaction was flushed with nitrogen, and filtered through celite. Evaporation of the solvent afforded 282 mg (49%) of BocLys[CO(CH ₂ ) ₃ NH ₂ . HCl]pyrrolidide. This product was dissolved in CH ₂ C1 ₂ (10 cm ³ ) and stirred, under a nitrogen atmosphere. Di-isopropylethylamine was added to adjust the pH to 9 before the introduction of pentafluorobenzεnesulfonyl chloride (45 mg, 0.17 mmol). This mixture was stirred for 16 h. The solvent was evaporated and the crude material treated in the standard procedure described in example one. Column chromatography (100% ethyl acetate to 10% methanol in ethyl acetate) afforded 33 mg (31%) of BocLys[CO(CH* ₂ ) ₃ NHSO ₂ Pfp]pyrrolidide as a colourless oil.

*H NMR (CDCI ₃ ), δ (ppm); 7.19 (1H, br.t, J = 6.3 Hz); 6.18 (1H, br.t, J = 6.6 Hz); 5.50 (1H, d, J = 8.4 Hz); 4.38 (1H, m); 3.65 - 3.16 (8H, m); 2.36 (2H, t, J = 6.8 Hz); 2.01 - 1.82 (8H, m); 1.69 - 1.41 (4H, m); 1.43 (9H, s).

This product was stirred in trifluoroacetic acid (10 cm ³ ) for 30 min. The solvent was evaporated and the residue dissolved in water, filtered and lyophiiised to yield 30 mg of H-Lys[CO(CH ₂ ) ₃ NHSO Pfp]Pτl (110) as a colourless oil.

FAB Mass Spec: Calculated 514.2; Found (M+H) ⁺ = 515.2.

EXAMPLE FOUR

H-Thr[(CH ₂ ) ₅ CH ₃ ]pyιτolicϋde (143)

Pyrrolidine (0.88 g, 12.4 mmol) was added to a solution of BocThrONSu (3.0 g, 9.5 mmol) in dry CH ₂ C1 ₂ (30 cm ³ ), under a nitrogen atmosphere. The reaction was stirred for 60 min at room temperature. The solvent was evaporated and die residue was treated in the standard procedure as described for example one. The residue was subjected to column chromatography (hexane:ethyl acetate, 30:70) to afford 2.50 g (96%) of l- N-(t-butoxycarbonyl)threonyl]pyπOlidine as a colourless oil.

*H NMR (CDC1 ₃ ), δ (ppm); 5.52 (1H, d, J = 6.5 Hz); 4.30 (1H, d,. J = 7.4 Hz); 4.16 (2H, m); 3.72 (1H, m); 3.46 (3H, m); 1.98 - 1.82 (4H, m); 1.43 (9H, s); 1.19 (3H, d, J = 7.1 Hz).

Sodium hydride (17 mg, 0.70 mmol) was added to a solution of l-[N-(t-butoxycarbonyl) threonyl]pyrrolidine in dry THF, at 0°C, under a nitrogen atmosphere. The mixture was stirred at 0°C for 15 min before the introduction of n-hexyl iodide (200 mg, 0.94 mmol). The reaction was then allowed to stir at room temperature for 16 h. The solvent was evaporated and the residue treated in the standard manner as described in example one. The crude product was subjected to column chromatography (hexane:ethyl acetate, 40:60) to afford 25 mg (10%) of BocThr[(CH ₂ ) ₅ CH ₃ ]pyrrolidide (143).

*H NMR (CDC1 ₃ ), δ (ppm); 5.50 (1H, d, J = 6.9 Hz); 4.48 (1H, m); 3.70 - 3.32 (7H, m); 1.92 - 1.80 (6H, m); 1.52 (2H, m); 1.42 (9H, s); 1.30 (6H, m); 1.22 (8H, d, J = 6.9 Hz); 0.83 (3H, t, J = 7.9 Hz).

BocThr[(CH ₂ ) ₅ CH ₃ ]pyrrolidide (20 mg, 0.06 mmol) was stirred in 4N HCl/dioxan (5 cm ³ ) for 60 min. The solvent was evaporated, the residue taken up in water, filtered and lyophiiised to yield H-Thr[(CH ₂ ) ₅ CH ₃ ]pyrrolidide (20 mg) as an orange oil. The product was purified by reverse phase HPLC to afford 15 mg of (143) as a colourless oil.

FAB Mass Spec: Calculated 256.2, Found (M+H) ⁺ = 257.3.

EXAMPLE FIVE

1.6 N ⁿ Butyl lithium (0.50 cm ³ , 0.76 mmol) was added to a stirred solution of cyclopentyl triphenyphosphonium bromide (287 mg, 0.69 mmol) in dry THF (6 cm ³ ), under a nitrogen atmosphere, maintaining the temperature at -30°C. After stirring for 60 min, the solution was further cooled to -50°C subsequent to the dropwise addition of a solution of N-(t-butoxycarbonyl)-L-isoleucinal (125 mg, 0.58 mmol, prepared by the method of Fehrentz and Castro, Synthesis, 1983, 676), in dry THF (4 cm ³ ). After the final addition, d e reaction was allowed to slowly attain room temperature, over 3.5 h.

- 45 -

The reaction was quenched witii saturated ammonium chloride solution (2 cm ³ ). This was diluted witii water (10 cm ³ ) and extracted with diethyl ether (3 x 20 cm ³ ). The combined ethereal layers were washed with water (10 cm ³ ), dried (Na ₂ SO ₄ ) and evaporated to yield 187 mg (>100%) of crude product Column chromatography (90:10, hexane:Et ₂ O) afforded 53 mg (34%) of Boc-Ile-ψ[CH=CH]pyrrolidide as a colourless oil.

*H NMR (CDC1 ₃ ), δ (ppm); 0.84 (3H, t, J = 6.9 Hz); 0.91 (3H, d, J = 7.3 Hz); 1.08

(1H, m); 1.44 (9H, s); 1.48 (1H, m); 1.64 (5H, m); 2.24 - 2.45 (4H, m); 4.08 (1H, br.s); 4.41 (1H, br.s); 5.12 (1H, dt, J = 2.3, 8.9 Hz).

¹³ C NMR(CDC1 ₃ ) δ (ppm); 155.8, 147.4, 119.1, 79.2, 54.8, 40.1, 34.2, 29.6, 28.9,

26.8, 26.6, 26.1, 15.0, 12.1.

Treatment of this product with 4N HCl/dioxan for 35 min removed the Boc-protecting group. ^" The reaction was evaporated, the residue dissolved in water, filtered and lyophiiised to yield 24 mg (63%) of H-Ile-ψ[CH=CH]pyrrolidide (149) as a foamy solid.

FAB Mass Spec: Calculated 167.2, Found (M+H) ⁺ = 168.2.

EXAMPLES SIX AND SEVEN

H-Ile[(2R)-cyano-ψ(CH=CH)pyτrolidide] (150) H-He[(2S)-cyano-ψ(CH=CH)ρyrrolidide] (151)

N-(t-Butoxycarbonyl)-L-isoleucinal (2.40 g, 11.2 mmol) and 2-oxy-l-triphenyl- phosphoranecyclopentane (4.61 g, 13.4 mmol, prepared by metiiod of H.O. House and H. Babed, J. Org. Chem., 1963, 28, 90) were heated, at reflux, in toluene, under a nitrogen atmosphere. After 15 h, the mixture was cooled, and d e solvent evaporated. Column chromatography (80:20, hexane:etiιyl acetate) of die crude residue afforded 2.33 g (74%) of BocBe-ψ[CH*=CH]pyrrolidin-2-one as a colourless oil.

^X H NMR (CDC1 ₃ ), δ (ppm); 6.29 (1H, dt, J = 2.6, 9.2 Hz); 4.59 (1H, br.d); 4.17 (1H, m), 2.82 (1H, m); 2.66 - 2.50 (2H, m); 2.34 (2H, t, J = 7.8 Hz); 1.96 (2H, q, J = 7.6 Hz); 1.44 (1H, m); 1.43 (9H, s); 1.12 (1H, m), 0.89 (3H, d, J = 5.3 Hz); 0.88 (3H, t, J = 6.9 Hz).

Diethylcyanophosponoacetate (0.30 cm ³ , 1.92 mmol) was added to a solution of BocHe-ψ[CH=CH]pyιτolidin-2-one (180 mg, 0.64 mmol) and LiCN (0.5 M in DMF, 3.84 cm ³ , 1.92 mmol) in dry DMF (2 cm ³ ), under a nitrogen atmosphere. The reaction was stirred at room temperature for 30 min. The mixture was diluted with water (20 cm ³ ) and then extracted with ethyl acetate (2 x 30 cm ³ ). The combined organic layers were washed with water (5 x 10 cm ³ ), dried (Na ₂ SO ₄ ) and evaporated to afford 360 mg (>100%) of crude product A portion of this crude cyano-phosphonate (284 mg, 0.64 mmol) was dissolved in dry THF, and stirred under nitrogen. rerr-Butanol (47 mg, 0.64 mmol) was added, followed by die dropwise addition of a solution of samarium (II) iodide (0.1 M in THF, 19.2 cm ³ , 1.92 mmol). After the final addition, the reaction was stirred for a further 30 min before the addition of 2N HCl (20 cm ³ ). The mixture was extracted with diethyl ether (3 x 30 cm ³ ). The combined ethereal layers were washed with 10% Na ₂ S ₂ O ₃ solution (10 cm ³ ), water (2 xlO cm ³ ) and brine (2 x 10 cm ³ ). The solution was dried (Na,SO ₄ ), evaporated and the crude residue subjected to column chromatography (90:10, hexane:ethyl acetate) to yield 122 mg (66%) of a diastereomeric mixture of Bocπe[2-(RS)-cyano-ψ(CH=CH)py_τolidine] as a colourless oil.

^l U NMR (CDC1 ₃ ), δ (ppm); 5.52 (1H, d, J = 9.6 Hz); 4.5 (1H, br.s); 4.12 (1H, m); 3.35 (1H, m); 2.57 (1H, m); 2.38 (1H, m); 2.17 (1H, m); 1.91 (2H, m); 1.69 (2H, m); 1.53 (1H, m); 1.43 (9H, s); 1.12 (1H, m); 0.92 (1.5 H, d, J = 7.3 Hz); 0.91 (1.5 H, d, J = 7.3 Hz); 0.89 (1.5 H, d, J = 6.6 Hz); 0.86 (1.5 H, t, J = 6.9 Hz).

Treatment of this diastereomeric mixture with 4N HCl/dioxan for 60 min removed the protecting group. Evaporation of die solvent and subsequent reverse phase HPLC of the residue afforded the two pure diastereomers.

(150), (47 mg, 60%) FAB Mass Spec: Calculated 192.2, Found (M+H) ⁺ = 193.2 (151), (28 mg, 36%) FAB Mass Spec: Calculated 192.2, Found (M+H) ⁺ = 193.2.

Preparative meti ods described herein in relation to Tables 1 - 8 and in examples one to seven form part of the present invention.

Abbreviations