| abstract |
The present invention relates to a compound of the formula [I]: , wherein R1 is lower alkyl which may have suitable substituent(s), R2 is amino, protected amino or guanidine, R3 is carboxy or protected carboxy, R4 is amino or protected amino, and A is lower alkylene, or pharmaceutically acceptable salt thereof, a process for Preparing a compound of the formula [I], and a pharmaceutical composition comprising a compound of the formula [I] in admixture with a pharmaceutically acceptable carrier. |