VLA-4 Antagonists

1 . A compound of formula I:

or a pharmaceutically acceptable salt thereof, wherein:

X and Y are independently chosen from (1) C 1-3 alkyl, (2) halogen, and (3) C 1-3 alkoxy;

Z is N or N + O − ;

R 1 is selected from (1) hydrogen, (2) C 1-10 alkyl, (3) —(C 1-10 alkyl)-aryl, (4) —(C 1-10 alkyl)-O—C 1-10 alkyl, (5) —(C 1-10 alkyl)-OC(O)—C 1-10 alkyl, (6) —(C 1-10 alkyl)-OC(O)-aryl, and (7) —(C 1-10 alkyl)-OC(O)O—C 1-10 alkyl; wherein alkyl is optionally substituted with one to three substituents independently selected from R a and aryl is optionally substituted with one to three substituents independently selected from Rb;

R 2 is hydrogen or methyl;

R 3 and R 4 are independently selected from (1) hydrogen, (2) C 1-10 alkyl, (3) —OR d , (4) —NR d R e , (5) —NR d S(O) m R e , (6) —NR d C(O)R e , (7) —NR d C(O)OR e and (8) —NR d C(O)NR d R e , wherein alkyl is optionally substituted with one to four substituents independently selected from R a ; or

R 3 and R 4 together with the carbon atoms to which they are attached form a monocyclic ring of 5 to 7 members containing 0-2 additional heteroatoms independently selected from O, S and N—R h , said ring optionally substituted with one to four substituents independently selected from R c ;

R 5 is selected from (1) C 1-10 alkyl, and (2) aryl;

R 6 is selected from (1) hydrogen, (2) halogen, and (3) —OR d ;

R a is selected from (1) —OR d , (2) —NR d S(O) m R e , (3) —NO 2 , (4) halogen, (5) —S(O) m R d , (6) —SR d , (7) —S(O) 2 OR d , (8) —S(O) m NR d R e , (9) —NR d R e , (10) —O(CR f R g ) n NR d R e , (11) —C(O)R d , (12) —CO 2 R d , (13) —CO 2 (CR f R g ) n CONR d R e , (14) —OC(O)R d , (15) —CN, (16) —C(O)NR d R e , (17) —NR d C(O)R e , (18) —OC(O)NR d R e , (19) —NR d C(O)OR e , (20) —NR d C(O)NR d R e , (21) —CR d (N—OR e ), (22) CF 3 , (23) —OCF 3 , (24) C 3-8 cycloalkyl, and (25) heterocyclyl; wherein cycloalkyl and heterocyclyl are optionally substituted with one to three groups independently selected from R c ;

R b is selected from (1) a group selected from R a , (2) C 1-10 alkyl, (3) C 2-10 alkenyl (4) C 2-10 alkynyl, (5) aryl, and (6) —(C 1-10 alkyl)-aryl, wherein alkyl, alkenyl, alkynyl, and aryl are optionally substituted with one to three substituents selected from a group independently selected from R c ;

R c is (1) halogen, (2) amino, (3) carboxy, (4) C 1-4 alkyl, (5) C 1-4 alkoxy, (6) aryl, (7) —(C 1-4 alkyl)-aryl, (8) hydroxy, (9) CF 3 , (10) OC(O)C 1-4 alkyl, (11) —CN, and (12) —SO 2 C 1-10 alkyl;

R d and R e are independently selected from hydrogen, C 1-10 alkyl, C 2-10 alkenyl, C 2-10 alkynyl, Cy and Cy-C 1-10 alkyl, wherein alkyl, alkenyl, alkynyl and Cy are optionally substituted with one to four substituents independently selected from R c ; or

R d and R e together with the atom(s) to which they are attached form a heterocyclic ring of 4 to 7 members containing 0-2 additional heteroatoms independently selected from O, S and N—R h ; wherein said ring is optionally substituted with one to four substituents independently selected from R c ;

R f and R g are independently selected from hydrogen, C 1-10 alkyl, Cy and Cy-C 1-10 alkyl; or

R f and R g together with the carbon to which they are attached form a ring of 5 to 7 members containing 0-2 heteroatoms independently selected from oxygen, sulfur and nitrogen;

R h is selected from R f and —C(O)R f ;

Cy is selected from cycloalkyl, heterocyclyl, aryl, and heteroaryl;

each m is independently 0, 1 or 2; and

each n is independently 1, 2, 3, or 4.

2 . The compound according to claim 1 wherein one of X and Y is halogen and the other is selected from halogen, C 1-3 alkyl and C 1-3 alkoxy.

3 . The compound according to claim 2 wherein one of X and Y is chloro and the other is chloro or methoxy.

4 . The compound according to claim 3 wherein X and Y are each chloro.

5 . The compound according to claim 1 wherein R 1 is selected from the group consisting of: hydrogen, C 1-4 alkyl, —(C 1-4 alkyl)OC(O)—C 1-4 alkyl, and —(C 1-4 alkyl)OC(O)—C 1-4 alkyl.

6 . The compound according to claim 1 wherein R 1 is hydrogen.

7 . The compound according to claim 1 wherein R 1 is C 1-4 alkyl.

8 . The compound according to claim 1 wherein R 3 is hydrogen and R 4 is NR d R e .

9 . The compound according to claim 1 wherein R 3 is NR d R e and R 4 is hydrogen.

10 . The compound according to claim 1 of formula Ia:

or a pharmaceutically acceptable salt thereof, wherein

Z is N or N + O − ;

R 1 is selected from hydrogen, C 1-10 alkyl, —(C 1-4 alkyl)-aryl, —(C 1-4 alkyl)-O—C 1-4 alkyl, and —(C 1-4 alkyl)-OC(O)—C 1-4 alkyl; and

R 5 is selected from C 1-4 alkyl and phenyl.

11 . The compound according to claim 1 selected from the following:

where R 1 is H or ethyl, and pharmaceutically acceptable salts thereof.

12 . The compound according to claim 1 of Formula Ib:

or a pharmaceutically acceptable salt thereof, wherein

Z is N or N + O − ;

R 1 is selected hydrogen and C 1-4 alkyl;

R 5 is selected from C 1-4 alkyl and phenyl; and

R 3 is hydrogen and R 4 is NR d R e or R 3 is NR d R e and R 4 is hydrogen.

13 . The compound according to claim 12 wherein one of R 3 or R 4 is hydrogen and the other of R 3 or R 4 is selected from the group consisting of: C 1-6 alkylamino, C 3-6 cycloalkylamino and

wherein k is 0 to 3.

14 . The compound according to claim 13 wherein: one of R 3 or R 4 is hydrogen and the other of R 3 or R 4 is selected from the group consisting of: cyclobutylamino, tert-butylamino and piperidino.

15 . A compound according to claim 1 selected from the group consisting of:

(R,S,S)—N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-4(R)-cyclobutylamino-(L)-prolyl}-4-[(3,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine, ethyl ester;

(R,S,S)—N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-4(R)-cyclobutylamino-(L)-prolyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine;

N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-3(−)-tert-butylamino-(L)-prolyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine, ethyl ester;

N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-3-tert-butylaminoprolyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine;

(S,R,S,S)—N—{N-[(3-Methylsulfonylbenzene)sulfonyl]octahydroisoindol-1-carboxyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine, ethyl ester;

(S,R,S,S)—N—{N-[(3-Methylsulfonylbenzene)sulfonyl]octahydroisoindol-1-carboxyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine;

(S,R,S,S)—N—{N-[(3-Phenylsulfonylbenzene)sulfonyl]octahydroisoindol-1-carboxyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine, ethyl ester;

(S,R,S,S)—N—{N-[(3-Phenylsulfonylbenzene)sulfonyl]octahydroisoindol-1-carboxyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine;

N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-4(R)-piperidino-(L)-prolyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine, ethyl ester;

N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-4(R)-piperidino-(L)-prolyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine;

N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-4(R)-3,3-dimethylpiperidino-(L)-prolyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine, ethyl ester; and

N—{N-[(3-Methylsulfonylbenzene)sulfonyl]-4(R)-3,3-dimethylpiperidino-(L)-prolyl}-4-[(3′,5′-dichloro-isonicotinoyl)amino]-(L)-phenylalanine,

or a pharmaceutically acceptable salt of any of the above.

16 . A pharmaceutical composition comprising a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier.

17 . Use of a compound of claim 1 or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment or prevention of diseases mediated by cell adhesion.

18 . The use of claim 17 wherein said disease is selected from asthma, multiple sclerosis, inflammatory bowel disease, chronic obstructory pulmonary disease, sickle cell anemia, leukemia, multiple myeloma, and rheumatoid arthritis.

19 . A method for preventing the action of VLA-4 in a mammal which comprises administering to said mammal a therapeutically effective amount of a compound according to claim 1 .