CEPHEMVERBINDUNGEN UND VERFAHREN ZU IHRER HERSTELLUNG

1. A compound of the formula: wherein R is lower alkyl, lower alkanoyl, aryl, ar(lower)alkyl or a heterocyclic group, each of which may have suitable substituent(s), R is carboxy or protected carboxy, R is hydrogen, halogen, hydroxy, lower alkoxy, acyloxy, lower alkylthio, lower alkenyl, lower alkenylthio, lower alkynyl, heterocyclicthio or a heterocyclic group, in which lower alkylthio, lower alkenyl, lower alkenylthio, heterocylicthio and a heterocyclic group may have suitable substituent(s), R and R are each hydrogen, halogen or arylthio, A is lower alkylene, and n is an integer of 0 or 1, and a pharmaceutically acceptable salt thereof, processes for preparation thereof and pharmaceutical composition comprising the same.