Reductive PET-fragmentation–cyclization processes of bicyclo[n.3.0]alkanones: synthesis of angular quasi-triquinane and propellane systems
摘要:
Bicyclo[3.3.0]octanone and bicyclo[4.3.0]nonanone derivatives with a cyclopropane unit in the alpha-position and an unsaturated side chain in the gamma-position of the carbonyl group undergo fragmentation-cyclization processes leading to quasi-triquinane systems upon reductive photoinduced electron transfer (PET). For example, the new angular triquinane derivative 6 and the new propellane derivative 12 were synthesized in one step from these starting materials in moderate to good yields. (C) 2003 Elsevier Ltd. All rights reserved.
通过分子内串联断裂-环化反应,通过光化学诱导的电子转移(PET)三环α-环丙基酮在羰基的γ位具有不饱和侧链,合成了稠合的三环角化合物。该反应导致β-环丙基键的区域选择性裂解,并通过酮基自由基/自由基阴离子作为反应性中间体形成有角稠合的三环系统。通常,三乙胺(TEA)在乙腈中用作强还原剂。环化步骤的首选区域选择性(外向与内向)取决于在三环α-环丙基酮的季碳中心(Cβ')处的取代模式。此外,我们还检查了有角二恶英-三喹烷的合成的两步途径,包括烯丙氧基取代的环戊[ c ]呋喃酮衍生物的光解以及随后的二恶唑-[4.5.5.5] fenestrane在还原条件下的β裂解。 PET条件。