A compound of the formula :
in which R1 is carboxy or protected carboxy,
R2 is hydroxy(lower)alkyl or protected hydroxy(lower)alkyl,
R3 is hydrogen or lower alkyl,
R4 is heterocyclic group, which may have suitable substituent(s), and
R5 is hydrogen or imino-protective group,
and pharmaceutically acceptable salts thereof, processes for their preparation and pharmaceutical compositions comprising them as an active ingredient. The invention further comprises intermediates of the formula
and process for the preparation thereof.
式中的化合物
其中 R1 为羧基或受保护的羧基、
R2 是羟基(低级)烷基或受保护的羟基(低级)烷基
R3 是氢或低级烷基
R4 是杂环基团,可带有合适的取代基,以及
R5 是氢或亚
氨基保护基团、
及其药学上可接受的盐、制备工艺和含有它们作为活性成分的药物组合物。本发明还包括式
及其制备工艺。