Catalytic Asymmetric Synthesis of Either Enantiomer of the Calabar Alkaloids Physostigmine and Physovenine
作者:Takaharu Matsuura、Larry E. Overman、Daniel J. Poon
DOI:10.1021/ja980788+
日期:1998.7.1
versatile asymmetric route to hexahydropyrrolo[2,3-b]indoles having carbon substituents at C-3a (Scheme 1) is demonstrated through enantioselective total syntheses of the Calabar alkaloids (−)-physostigmine (2), (−)-physovenine (10), and their enantiomers. The synthesis of enantiopure (−)-physostigmine proceeds from commercially available 2-butyn-1-ol (11) and N-methyl-p-anisidine (15) in 15−20% overall yield
通过对映选择性全合成卡拉巴生物碱 (-)-毒扁豆碱 (2), (-)-physovenine 证明了一种潜在的通用不对称途径,以在 C-3a 处具有碳取代基的六氢吡咯并 [2,3-b] 吲哚(方案 1) (10) 及其对映异构体。对映体纯 (-)-毒扁豆碱的合成从市售的 2-丁炔-1-醇 (11) 和 N-甲基-对茴香胺 (15) 开始,通过八种分离和纯化的中间体以 15-20% 的总产率合成。中心步骤是 (Z)-2-甲基-2-丁烯苯胺 17 的催化不对称 Heck 环化以 84% 的产率和 95% 的 ee 形成羟吲哚醛 (S)-19。