Gold-Catalyzed Deoxygenative Nazarov Cyclization of 2,4-Dien-1-als for Stereoselective Synthesis of Highly Substituted Cyclopentenes
作者:Chung-Chang Lin、Tse-Min Teng、Chung-Chih Tsai、Hsin-Yi Liao、Rai-Shung Liu
DOI:10.1021/ja806415t
日期:2008.12.3
annulation products reveals evidence for the participation of Nazarov cyclization. This deoxygenative cyclization is extensible to a tandem intramolecular cyclization/nucleophilic addition cascade, giving polycyclic carbo- or oxacyclic compounds with controlled stereochemistry. This new gold catalysis is applied to a short synthesis of natural compounds of the brazilane family, including brazilane, O-trimethyl-
用烯丙基硅烷和 PPh(3)AuSbF(6) (3 mol %) 处理 2,4-dien-1-als 导致形成 1,4-双(烯丙基)环戊烯基产物;根据催化剂筛选,这种金催化剂优于常用的路易斯酸。这种金催化的脱氧环化反应与各种基于氧、胺、硫、氢和碳的亲核试剂相容。2,4-dien-1-als 与富电子烯烃和芳烃的多种环化证明了这种新催化的价值,提供了对复杂环戊烯骨架的轻松访问。环化产物的结构分析揭示了 Nazarov 环化参与的证据。这种脱氧环化可扩展为串联的分子内环化/亲核加成级联,得到具有受控立体化学的多环碳或氧杂环化合物。这种新的金催化应用于巴西烷家族天然化合物的短程合成,包括巴西烷、O-三甲基巴西烷和 O-四甲基巴西烷。