Highly efficient and concise synthesis of both antipodes of SB204900, clausenamide, neoclausenamide, homoclausenamide and ζ-clausenamide. Implication of biosynthetic pathways of clausena alkaloids
Zetaclausenamide, which was isolated as a hepatoprotective agent from the leaves of medicinal plant Clausena lansium, was synthesized for the first time in six steps including Darzen's condensation, photoisomerization, and the final cyclization reactions.
Reversal of Nucleophilicity of Enamides in Water: Control of Cyclization Pathways by Reaction Media for the Orthogonal Synthesis of Dihydropyridinone and Pyrrolidinone <i>Clausena</i> Alkaloids
作者:Luo Yang、Qi-Yu Zheng、De-Xian Wang、Zhi-Tang Huang、Mei-Xiang Wang
DOI:10.1021/ol800740h
日期:2008.6.1
A highly efficient, metal-free, and divergent method for the synthesis of 3,4-dihydropyridin-2-one and pyrrolidin-2-one Clausena alkaloids and their analogs is reported. While the oxirane-containing enamides underwent the TFA-mediated 6-endo-enamide-epoxide cyclization reaction in (BuOH)-O-t to produce homoclausenamides, an unprecedented nucleophilic reaction occurred at the alpha-carbon of enamides in water to yield 5-endo-enamide-epoxide cyclization products in excellent yields. The reversal of nucleophilicity of enamides in intramolecular cyclization is discussed in terms of steric and electronic effects of the oxirane-containing enamides.
Study of the intramolecular cyclization of N-methyl-3-phenyl-N-(2-(E)-phenylethenyl)-trans(cis)-oxiranecarboxamide – Syntheses of Homoclausenamide and Dehydroclausenamide
作者:Nianchun Ma、Kemei Wu、Liang Huang
DOI:10.1016/j.ejmech.2007.11.022
日期:2008.8
Homoclausenamide was synthesized for the first time, and the intramolecular cyclization study of N-methyl-3-phenyl-N-(2-(E)-phenylethenyl)-trans(cis)-oxiranecarboxamide well demonstrated how the stereochemistry affects the cyclization paths. (c) 2007 Elsevier Masson SAS. All rights reserved.