A series of twelve highly active aminomethyl-THF l~methylcarbapenems 3a-! were synthesized. Of these, carbapenems 3a-f demonstrated a spectrum of antimicrobial activity comparable to those of imipenem and meropenem with the exception of only moderate anti-pseudomonal activity. Most importantly, they demonstrated moderate intrinsic oral activity against an E. coli infection in mice. © 1997 Elsevier Science Ltd.