摘要:
Intramolecular Rh(II) carboxylate catalyzed cyclization of an alpha-diazo beta-methylene ketone to form a fused cyclopropane is shown to compete efficiently with beta-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 PGE2 methyl ester 1. Prostaglandins having the 8-beta configuration, recently identified as being physiologically important, can also be prepared using this approach.