Antibacterial agents

1. A compound of formula (I)

wherein:

Z 1 , Z 3 , and Z 4 are independently N or CR 1a ;

Z 2 , Z 5 and Z 6 are each CR 1a ;

R 1 and R 1a are independently at each occurrence hydrogen; cyano; halogen; hydroxy; (C 1-6 ) alkoxy unsubstituted or substituted by (C 1-6 ) alkoxy, hydroxy, amino, piperidyl, guanidino or amidino any of which is unsubstituted or N-substituted by one or two (C 1-6 ) alkyl, (C 1-6 ) alkylsulphonyl, CONH 2 , hydroxy, (C 1-6 ) alkylthio, heterocyclylthio, heterocyclyloxy, arylthio, aryloxy, acylthio, or (C 1-6 ) alkylsulphonyloxy; (C 1-6 )alkyl; (C 1-6 )alkylthio; trifluoromethyl; trifluoromethoxy; nitro; azido; (C 1-6 )alkylsulphonyl; (C 1-6 )alkylsulphoxide; arylsulphonyl; arylsulphoxide; or an amino, piperidyl, guanidino or amidino group unsubstituted or N-substituted by one or two (C 1-6 )alkyl or (C 1-6 )alkylsulphonyl groups; or R 1 and R 1a of Z 2 together form ethylenedioxy;

A is CR 2 R 3 ;

R 2 is hydrogen; halogen; hydroxy; or (C 1-6 )alkoxy; and R 3 is hydrogen;

W 1 and W 3 are CR 4 R 5 ;

R 4 is hydrogen; halogen; hydroxy; (C 1-6 )alkyl; (C 1-6 )alkoxy; or NR 1b R 1b′ ; and R 5 is hydrogen or (C 1-6 )alkyl;

R 1b and R 1b′ are independently hydrogen; (C 1-6 )alkyl; aryl; heteroaryl; or together with the nitrogen they are attached form an aziridine, azetidine, pyrrolidine, piperidine or hexamethyleneimine ring (wherein said aziridine, azetidine, pyrrolidine, piperidine or hexamethyleneimine ring is optionally substituted with 1 to 3 substitutents selected from halogen, (C 1-6 )alkyl, hydroxy or aryl);

W 2 is CR 6 ;

R 6 is hydrogen; halogen; hydroxy; (C 1-6 )alkyl; NR 1c R 1c′ ; or (C 1-6 )alkoxy;

R 1c and R 1c′ are independently hydrogen; (C 1-6 )alkyl; aryl; heteroaryl; or together with the nitrogen they are attached form an aziridine, azetidine, pyrrolidine, piperidine or hexamethyleneimine ring (wherein said aziridine, azetidine, pyrrolidine, piperidine or hexamethyleneimine ring is optionally substituted with 1 to 3 substitutents selected from halogen, (C 1-6 )alkyl, hydroxy or aryl);

B is CR 7 R 8 ;

R 7 and R 8 are independently hydrogen or (C 1-6 )alkyl;

R 9 is hydrogen; aryl; heteroaryl; (C 1-6 )alkyl unsubstituted or substituted by one or two (C 1-6 )alkoxy, carboxy, hydroxy, amino, piperidyl, piperazinyl, morpholino, guanidino, or amidino, any of which is unsubstituted or N-substituted by one or two aryl, heteroaryl, halogen, unsubstituted (C 1-6 )alkyl, (C 1-6 )alkylsulphonyl, arylsulphonyl, hydroxy, (C 1-6 )alkylthio, heterocyclylthio, heterocyclyloxy, arylthio, aryloxy, or (C 1-6 )alkylsulphonyloxy; (C 1-6 )alkylcarbonyl; or (C 2-6 )alkenylcarbonyl;

R 10 is a group —U—R 11 where R 11 is represented by the following group:

U is C(═O); SO 2 ; or CR 16 R 17 ; and

R 16 and R 17 are independently selected from H; aryl; heteroaryl; (C 1-6 )alkyl; (C 1-6 )alkyl substituted by (C 1-6 )alkoxy, hydroxy, amino, piperidyl, piperazinyl, morpholino, guanidino, or amidino, any of which is substituted or N-substituted by one or two H, aryl, heteroaryl, halogen, cyano, CF 3 , (C 1-6 )alkyl, (C 1-6 )alkylsulphonyl, arylsulphonyl, hydroxy, (C 1-6 )alkylthio, heterocyclylthio, heterocyclyloxy, arylthio, aryloxy, or (C 1-6 )alkylsulphonyloxy; (C 1-6 )alkoxy-substituted(C 1-6 )alkyl; hydroxy-substituted(C 1-6 )alkyl; amino-substituted(C 1-6 )alkyl, which is N-substituted by one or two (C 1-6 )alkyl, (C 1-6 )alkylsulphonyl, or arylsulphonyl; (C 1-6 )alkylcarbonyl; (C 2-6 )alkenylcarbonyl; (C 1-6 )alkoxycarbonyl; CO 2 H; or CF 3 ,

or a pharmaceutically acceptable salt thereof.

2. A compound or salt according to claim 1 , wherein:

Z 1 and Z 4 are N; and

Z 3 is CR 1a .

3. A compound or salt according to claim 1 , wherein:

R 1 is OCH 3 .

4. A compound or salt according to claim 1 , wherein R 1a is at each occurrence independently hydrogen; halogen; or cyano.

5. A compound or salt according to claim 2 , wherein:

R 1a of Z 2 , Z 3 and Z 5 are each hydrogen;

R 1a of Z 6 is hydrogen, fluorine or cyano; and

R 1 is OCH 3 .

6. A compound or salt according to claim 5 , wherein:

R 2 is hydrogen or hydroxy;

R 4 is hydrogen; halogen; hydroxy; (C 1-6 )alkyl; or (C 1-6 )alkoxy;

R 5 is hydrogen or (C 1-6 )alkyl;

R 6 is hydrogen; hydroxy; halogen; or (C 1-6 )alkyl;

R 9 is hydrogen or (C 1-6 )alkyl; and

U is CH 2 ; SO 2 ; or C(═O).

7. A compound according to claim 1 , wherein the compound is:

a) 6-({[(1-{2-[3-fluoro-6-(methyloxy)-1,5-naphthyridin-4-yl]ethyl}-3-azetidinyl)methyl]amino}methyl)-2H-pyrido[3,2-b][1,4]thiazin-3(4H)-one

b) 6-({[(1-{2-[3-fluoro-6-(methyloxy)-1,5-naphthyridin-4-yl]ethyl}-3-azetidinyl)methyl]amino}methyl)-2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one

or a pharmaceutically acceptable salt thereof.

8. A pharmaceutical composition comprising a compound or salt according to claim 1 and a pharmaceutically acceptable carrier.

9. A method of treating bacterial infections in mammals which comprises administering to a mammal in need thereof an effective amount of a compound or salt according to claim 1 wherein the bacterial infections are caused by gram positive organisms selected from the group consisting of Staphyloccocus auresu, Staphlyococcus epidemidis, Streptococcus pneumoniae, Streptococcus pyogenes, Enterococcus faecalis, Entermococcus faecium ; and gram negative organisms selected from the group consisting of Haemophilus influenza E. coli , and Moraxella catarrhaliz Ravasio.