Enantioselective Total Synthesis of Guanacastepene N Using an Uncommon 7-Endo Heck Cyclization as a Pivotal Step
作者:Shin Iimura、Larry E. Overman、Ralph Paulini、Armen Zakarian
DOI:10.1021/ja0650504
日期:2006.10.1
A convergent, enantioselective total synthesis of (+)-guanacastepene N was developed that features a 7-endo Heck cyclization as the key step. In the course of this synthesis, short syntheses of the enantiomerically pure cyclopentenone and cyclohexene building blocks 5 and 6, which constitute A and C ring fragments of guanacastepene N, were developed. These fragments were linked by a challenging conjugate
开发了 (+)-guanacastepene N 的收敛、对映选择性全合成,其特征是 7-endo Heck 环化作为关键步骤。在该合成过程中,开发了对映异构纯环戊烯酮和环己烯结构单元 5 和 6 的短合成,它们构成了胍那卡司汀 N 的 A 和 C 环片段。这些片段通过具有挑战性的共轭加成反应连接,该反应也产生了 C11 季碳立体中心。区域选择性 7-endo Heck 环化产生了一个三环中间体,该中间体经过精心设计以完成 guanacastepene N 的第一次全合成和 guanacastepene 天然产物的第二次对映选择性全合成。