| 摘要 |
A compound of the formula : <CHEM> wherein R<1> is amino or a protected amino group, R<2> is an organic group, R<3> is hydrogen, lower alkyl, hydroxy(lower)alkyl, protected hydroxy(lower)alkyl, amino(lower)alkyl, protected amino(lower)alkyl or an imino protective group, R<4> is hydrogen, lower alkyl or lower alkylthio, A is lower alkylene which may be substituted with suitable substituent(s) and Z is N or CH, and a pharmaceutically acceptable salt thereof, processes for its preparation and pharmaceutical compositions comprising them or a pharmaceutically acceptable salt thereof in admixture with pharmaceutically acceptable carriers. |
