1. A compound of formula (I) or a stereoisomer thereof or a pharmaceutically acceptable salt thereof； wherein: R is: (a) SOM, (b) SONH, (c) POM, (d) CHCOOM, (e) CFCOOM, (f) CHFCOOM or (g) CF； M is hydrogen or a cation； R is: (a) hydrogen, (b) (CH) -R or (c) COORn is 0, 1 or 2； R is: (a) hydrogen, (b ) C-Calkyl optionally substituted with one or more substituents independently selected from halogen, OR, CN, COOR, CONRR, NRR, NRCOR, NRCONRR, heterocyclyl, heteroaryl, cycloalkyl or aryl, (c) CN, (d) NRR, ( e) CONRR, (f) NHCONRR, (g) aryl, optionally substituted with one or more substituents independently selected from C-C1-6 alkyl, OR, NRR, halogen, CN, CONRR, SO-alkyl, SO-aryl, OSO-alkyl, OSO-aryl or NHCONRR, (h) heterocyclyl, optionally substituted with one or more substituents, independently selected from C-C1-6 alkyl, OR, NRR, halogen, CN, CONRR, SO-alkyl, SO-aryl, OSO-alkyl, OSO-aryl or NHCONRR, (i) heteroaryl, optionally substituted with one or more substituents independently selected from C -Calkyl, OR, NRR, halogen, CN, CONRR, SO-alkyl, SO-aryl, OSO-alkyl, OSO-aryl or NHCONRR, (j) cycloalkyl optionally substituted with one or more substituents, optionally optionally selected from C-C1-6 alkyl, OR, NRR, halogen, CN, CONRR, SO-alkyl, SO-aryl, OSO-alkyl, OSO-aryl or NHCONRR, (k) cycloalkyl substituted with C-C1-6 alkyl, where C-C1-6 alkyl is optionally substituted by one or more substituents independently selected from OR, NRR, halogen, CN or CONRR, or (l) OR； R is: (a) hydrogen, (b) C-Calkyl optionally substituted by one or more substituents independently selected from halogen, OR, CN, COOR, CONRR, NRR, NRCOR, heterocyclyl, heteroaryl, cycloalkyl or aryl, (c) aryl, optionally substituted with one or more substituents, independently selected from C-C1-6 alkyl, OR, NRR, halogen, CN, CONRR, SO-alkyl, SO-aryl, OSO-alkyl, OSO-aryl or NHCONRR, (d) heterocyclyl, optionally substituted with one or more substituents independently selected from C-C1-6 alkyl, OR, NRR,1. Сое
