NEW CARBAPENEM DERIVATIVE

PURPOSE: To obtain the subject new compound useful as an antibacterial agent against Gram-positive bacteria, Gram-negative bacteria, esp. resistant bacteria such as multiple drug-resistant MRSA and drug-resistant Pseudomonas aeruginosa. CONSTITUTION: This new compound is expressed by formula I (R1 is H or a lower alkyl such as methyl; R2 is a negative electric charge, H, or an ester residue such as a lower alkanoyloxy or a lower alkyl group; A ring is an unsaturated N-contg. 5 to 6-membered heterocycle; dotted lines means that one of them is double bond, the other being single bond; (+) is positive electric charge). The compound of formula I is obtained by reaction of an intermediate expressed by formula II with a thiol compound of formula III followed by either removing the protecting group by reduction or conducting an esterification or salt-forming reaction. The reaction is pref. made in an organic solvent such as acetone in the presence of a base such as trimethylamine under cooling.