NUCLEAR ANALOGS OF β-LACTAM ANTIBIOTICS. XIV. SYNTHESIS OF PENEMS VIA (4-TRITYLTHIO-2-AZETIDINON-1-YL)TRIPHENYLPHOSPHORANYLIDENEACETATES

The preparation of (4-tritylthio-2-azetidinon-l-yl)triphenylphosphoranylideneacetates from 4-acetoxyazetidin-2-one is described. They are easily converted to mercuric or silver mercaptides. These mercaptides are acylated with a wide variety of acylating agents and cyclized to 2-substituted penem-3-carboxylates.