1993 年 51 巻 7 号 p. 641-651
The cleavage reaction of cyclopropane ring is one of the useful method in organic synthesis. Especially, the sequence of cyclopropanation-homoconjugate addition is one of the accessible methods for the synthesis of natural products possessing ring- and side-chain contiguous chiral centers. This report deals with the synthetic studies of biologically active natural products possessing such chiral centers by using the opening reaction of double activated cyclopropanes.
Cyclopropane derivatives have been synthesized from methyl acetoacetate by alkylation, diazo transfer followed by copper-mediated cyclopropanation. The various adducts were obtained by homoconjugate addition of nucleophiles (Gilmann reagents, Grignard reagents, cyanide anion, methanol etc.) to cyclopropanes. The opening reaction proceed with inversion of absolute configuration at the apical carbon of the cyclopropane. The adducts were converted effectively into several biologically active natural products and/or known synthetic intermediates.