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.
Highly Efficient and Stereoselective N-Vinylation of Oxiranecarboxamides and Unprecedented 8-<i>endo</i>-Epoxy-arene Cyclization: Expedient and Biomimetic Synthesis of Some <i>Clausena</i> Alkaloids
作者:Luo Yang、Gang Deng、De-Xian Wang、Zhi-Tang Huang、Jie-Ping Zhu、Mei-Xiang Wang
DOI:10.1021/ol070292+
日期:2007.3.1
Catalyzed by CuI/N,N-dimethylglycine, oxiranecarboxamides underwent a highly efficient and stereoselective N-vinylation reaction with (Z)-1-aryl-2-bromoethenes to afford the corresponding enamides. The method has been applied to a straightforward synthesis of (-)-(2R,3S)-SB204900, the enantiomer of the natural product. Following a hypothetic biomimetic pathway, both (+)-(5R,6S)-xi-Clausenamide and (-)-(5R,6S)-balasubramide have been efficiently synthesized for the first time through the unprecedented intramolecular 8-endo-epoxy-arene cyclization of (Z)-N-(phenylvinyl)oxiranecarboxamides.