Synthesis of carbapenems with a sulfonyl group in the C-6 side-chain and their biological activity.

A new type of 5,6-cis-carbapenems (racemic) having a sulfonyl group in the C-6 side-chain were synthesized by employing the synthetic methodology reported in our previous papers, and an alternative stereocontrolled synthesis of these 5,6-cis-carbapenems was achieved starting from 8oxo-7-azabicyclo[4.2.0]oct-3-ene (14) via an intramolecular aldol condensation as the key step. Chiral 5,6-cis-carbapenems were also synthesized from (1S,6R)-8-oxo-7-azabicyclo[4.2.0]oct-3-ene (29), which was derived from cis-1,2,5,6-tetrahydrophthalic anhydride. The carbapenems thus obtained proved to be highly stable to the mouse kidney homogenate, and most of them showed good antibacterial activity as well as potent ƒÀ-lactamase inhibitory activity.