The present invention provides ²-methyl carbapenem compounds or pharmaceutically acceptable salts thereof, wherein: R 1 is hydrogen or methyl； P is hydrogen or hydroxyl； M is H or a group such that CO 2 M is a carboxylic acid, a carboxylate anion, a pharmaceutically acceptable ester group, or a carboxylic acid protected by a protecting group； and Y is -(CH 2 ) n -A, wherein n is 0-4 and A is -CN, -OR 2 , -SR 2 , -N(R 2 ) 2 , CO 2 R 2 , C(=O)-N(R 2 ), -C(=O)-NR 2 SO 2 N(R 2 ) 2 , NR 2 SO 2 N(R 2 ) 2 , NH-C(=NR 2 )-N(R 2 ) 2 , -S-C(=NR 2 )-N(R 2 ) 2 , wherein each R 2 is independently H or C 1 -C 4 alkyl and pharmaceutical compositions useful in the treatment of bacterial infections and methods for treating such infections using such compounds and/or compositions. The invention includes administering an effective amount of a carbapenem compound or salt and/or prodrug thereof to a host in need of such a treatment. The present invention is also in the field of synthetic organic chemistry and is specifically provides an improved method of synthesis of ²-methyl carbapenems which arc useful as antibacterial agents.
