| 摘要 |
A compound of the formula : <CHEM> wherein R<1> is hydrogen or an acyl group, R<2> is an acyl group, R<3> is carboxy(lower)alkyl, lower alkyl substituted with carboxy and one or more halogen atom(s), protected carboxy(lower)alkyl, carboxyaryl, protected carboxyaryl, carboxy, protected carboxy, hydroxy(lower)alkyl, sulfino(lower)alkyl, phosphono(lower)alkyl, protected phosphono(lower)alkyl or halo(lower)alkyl, R<7> is hydrogen or lower alkyl, and A is <CHEM> (in which R<8> is hydrogen or lower alkyl), and a pharmaceutically acceptable salt thereof, processes for its preparation and pharmaceutical compositions comprising them. The invention also relates to intermediates of the formula <CHEM> and process for production thereof. r |
