Several substituted cyclopropylallenes were coupled under Heck conditions with aryl iodides and aryl bromides, respectively, and the 1,3,5-hexatrienes resulting with ring-opening of the cyclopropyl group, were captured in situ by a number of reactive dienophiles to yield oligosubstituted cyclohexene derivatives (8–86 %, 33 examples) with diastereomeric ratios ranging from 1.4:1 to 4.9:1. The influences
几个取代的环丙基
丙二烯在 Heck 条件下分别与芳基
碘化物和芳基
溴化物偶联,环丙基开环产生的
1,3,5-己三烯被许多反应性亲二烯体原位捕获,得到低聚取代的
环己烯非对映体比率范围为 1.4:1 至 4.9:1 的衍
生物(8-86%,33 个实例)。已经阐述了取代基的数量、性质和模式的影响。[4+2] 环加成反应最有可能通过中间体良好稳定的 1,6-两性离子中间体分两步进行。(© Wiley-
VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)