摘要:
Rhodium(II) carboxylate catalyzed C-H insertion to form a cyclopentane is shown to compete effectively with beta-hydride elimination, except when the beta-hydrogen is ternary. Cyclization of diazo ester 27 gives 28, which is converted in three steps to (+/-)-tochuinyl acetate 25. Both the cyclization to form 28 and the alkylation of 28 proceed with remarkable diastereoselectivity.