Intramolecular Rh (I1) carboxylate catalyzed cyclization of an a-diazo@-methylene ketone to form a fused cyclopropane is shown to compete efficiently with 8-hydride elimination, so long as a catalyst derived from an electron-donating carboxylate is used. Cyclization of diazoketone 3 gives 2, which on opening with thiophenol followed by oxidative rearrangement gives PGE, methyl ester 1. Prostaglandins having the 8-8 configuration, ...
