Synthesis and antibacterial activity of (1′R, 5R, 6R)-2-tert-butyl-6-(1′-hydroxyethyl)penem-3-carboxylic acid

As with the oxapenems, the 2-tert-butyl substituents substantially increased the hydrolytic stability of penems. The corresponding penems 1 and 2 were prepared and found to be extremely stable compounds. 2 showed good in vitro activity against gram-positive bacteria.