Alkali Base-Initiated Michael Addition/Alkyne Carbocyclization Cascades
作者:Christopher Kourra、Felix Klotter、Filippo Sladojevich、Darren J. Dixon
DOI:10.1021/ol2033674
日期:2012.2.17
A new cascade reaction involving an intramolecular Michael addition followed by an alkyne carbocyclization is presented. The reaction is promoted by a substoichiometric amount of KHMDS and represents one of the rare examples where the carbocyclization of an unactivatedalkyne is mediated by an alkali metal base, under mild conditions. The reaction allows the generation of functionally dense, stereochemically
An efficient synthetic route toward the highly congested [5‐6‐7] tricycliccore of calyciphylline A‐type alkaloids has been developed. This approach features a highly efficient intramolecular Diels–Alder cycloaddition to establish the aza‐five‐membered C ring as well as the C1 all‐carbon quaternary center, and a subsequent cyclopropanation together with a ring‐expansion reaction of the resulted adduct