Synthesis and antibacterial activity of 2-alkoxy penems

The phosphite mediated Oxalimide cyclization reaction was extended to 4-dithiocarbonates of N-oxalyl-2-azetidinones to synthesize 2-alkoxy penems 3. In general, the in vitro antibacterial potency of compounds 3 was weak compared to the highly potent 2-alkylthiopenems 2. The Oxalimide penem synthesis was applied to dithiocarbonates 9 to afford, after deprotection, a selected series of 2-alkoxy penems 15. Compounds 15 have weak antibacterial activity relative to the corresponding 2-alkylthio analogs.