Stereocontrolled synthesis of a fully functionalized AB ring moiety of fomitellic acids was accomplished. The tricyclic skeleton was stereoselectively constructed by means of titanium(III)-mediated radical cascade cyclization of epoxypolyene. The stereochemistry at C1 and C3 was controlled by a vinylogous Mukaiyama aldol reaction and a Sharpless asymmetric epoxidation, respectively.
2-Alkenyl-substituted cyclopropylacetaldehydes undergo enantioselective vinylcyclopropane-cyclopentene (VCP-CP) rearrangement using a Jorgensen-Hayashi-type catalyst. The reaction proceeds through enamine/iminium activation and comprises the in situ generation of a donor-acceptor cyclopropane intermediate that undergoes ring-opening/cyclization. Computational studies together with the experimental
2-烯基取代的环丙基乙醛使用 Jorgensen-Hayashi 型催化剂进行对映选择性乙烯基环丙烷-环戊烯 (VCP-CP) 重排。该反应通过烯胺/亚胺活化进行,包括原位生成供体-受体环丙烷中间体,该中间体经历开环/环化。计算研究连同实验数据支持 II 型 DYKAT 过程运行。