Novel Variant of the Tricyclooctanone Approach to Cyclopentanoid Natural Products. Synthesis of (±)-Coriolin. Preliminary Communication
作者:Martin Demuth、Peter Ritterskamp、Kurt Schaffner
DOI:10.1002/hlca.19840670741
日期:1984.11.7
6-trimethylbicyclo[2.2.2]oct-7-ene-2,5-dione (2a/2b) is described (yield 2a/2b8: 28%). The sequence is unprecedentedly short and avoids difficult separation problems. The key step in the scheme is a novel facet of oxadi-π-methane photochemistry, i.e., the steering by subtle steric effects of the β,γ-unsaturated ϵ-diketone to undergo a regioselective photorearrangement involving one β,γ-enone partial
描述了由3,3,6-三甲基双环[2.2.2] oct-7-ene-2,5-dione(2a / 2b)分11步合成抗肿瘤倍半萜烯coriolin(9 ;外消旋体)的全过程(收率2a / 2b 8: 28%)。该序列前所未有地短,并且避免了困难的分离问题。该方案的关键步骤是恶二酮-π-甲烷光化学的一个新方面,即通过微妙的立体效应使β,γ-不饱和γ-二酮发生转向以进行涉及一个β,γ-烯酮部分发色团的区域选择性光重排。 。此外,可以在异常高的浓度(≥20%溶液)下进行的整体光转化也涉及NorrishI型方法使两个差向异构起始烯二酮2a和2b平衡,有利于所需的立体异构体。