Radical-initiated polyolefinic cyclizations in linear triquinane synthesis. model studies and total synthesis of (±)-hirsutene
作者:Dennis P. Curranl、Donna M. Rakiewicz
DOI:10.1016/s0040-4020(01)97175-3
日期:1985.1
model is proposed. Cyclizations of 28 and 29 to 30 and 31 demonstrate the viability of a tandem hexenyl-hexynyl cyclization. The work culminates with a total synthesis of (±)hirsutene. A selective approach to methyl substituted vinyl lactones by Claisen rearrangement-phenylselenolactonization-elimination of acetoxy cyclopentenols is exemplified by the synthesis of 12. Tandem cyclization of 38 produces
报道了新颖的自由基引发的聚烯烃环化方法对线性缩合的环戊烷的详细信息。该策略分三个阶段执行:(1)乙烯基内酯的Sn2'-反开放以生成反式3,5-二取代的环戊烯;(2)快速制备成环化前体;以及(3)单步串联自由基环化生成顺式-反式三环[3.3.0]十一烷。模型基底16a和16b分别给出高产率的三环产物17和18。提出了通过Beckwith过渡态模型合理化有趣的内在选择性的努力。28和29至30和31的环化显示了串联己烯基-己炔基环化的可行性。这项工作最终以(±)hirsutene的总合成而告终。通过克莱森重排-苯基硒烯内酯化-消除乙酰氧基环戊烯醇的甲基取代乙烯基内酯的选择性方法可通过合成12来举例说明。38的串联环化在一个步骤中产生hirsutene(1)。或者,将37环合,得到三甲基甲硅烷基hirsutene。