| 摘要 |
A compound of the formula: …<CHEM>… in which… R<1> and R<2> are each hydrogen, halogen, lower alkoxy or halo(lower)alkyl,… R<3> is aryl or ar(lower)alkyl, both of which may have one or more suitable substituent(s), or heterocyclic(lower)alkyl,… R<4> is carboxy or protected carboxy,… A is oxygen or sulfur atom,… Y is carbonyl, thiocarbonyl or sulfonyl and… Z is lower alkylene,… and pharmaceutically acceptable salts thereof, processes for their preparation and pharmaceutical compositions comprising them in admixture with pharmaceutically acceptable carriers. |
