【文章名】Reversal of Nucleophilicity of Enamides in Water: Control of Cyclization Pathways by Reaction Media for the Orthogonal Synthesis of Dihydropyridinone and Pyrrolidinone Clausena Alkaloids.
Reversal of Nucleophilicity of Enamides in Water: Control of Cyclization Pathways by Reaction Media for the Orthogonal Synthesis of Dihydropyridinone and Pyrrolidinone Clausena Alkaloids.
[摘要]：A highly efficient, metal-free, and divergent method for the synthesis of 3,4-dihydropyridin-2-one (e.g. I) and pyrrolidin-2-one (e.g. II) Clausena alkaloids and their analogs from oxirane emamides (e.g. III) is reported. While the oxirane-contg. enamides underwent the TFA-mediated 6-endo-enamide-epoxide cyclization reaction in t-BuOH to produce homoclausenamides, an unprecedented nucleophilic reaction occurred at the a-carbon of enamides in water to yield 5-endo-enamide-epoxide cyclization products in excellent yields. The reversal of nucleophilicity of enamides in intramol. cyclization is discussed in terms of steric and electronic effects of the oxirane-contg. enamides.
