Photochemical reactions of chloranil with norbornene,† bicyclo[2.1.1]hex-2-ene and cyclopentene. A novel intermolecular photocycloaddition
作者:Max Braun、Manfred Christl、Eva-Maria Peters、Karl Peters
DOI:10.1039/a903600h
日期:——
The irradiation of chloranil (CA), dissolved in benzene, in the presence of norbornene gave the α,β-unsaturated α,γ-dichloro-γ-lactone 1 in 67% yield. Heretofore, such a product had not been observed in a photochemical reaction of CA with an alkene. In addition, bicyclo[2.1.1]hex-2-ene and cyclopentene furnished compounds such as 1. However, conventional products of the reaction of 3CA with alkenes
在降冰片烯的存在下,辐照溶于苯的氯苯甲醛(CA)可以得到67%的α,β-不饱和α,γ-二氯-γ-内酯1。迄今为止,在CA与烯烃的光化学反应中还没有观察到这种产物。另外,双环[2.1.1]己-2-烯和环戊烯提供的化合物如1。然而,在这些情况下,也相当程度地形成了3 CA与烯烃反应的常规产物。作为通往1的第一步,将[4 + 2]环加成3提出将CA加到降冰片烯上会产生类型23的双自由基,该自由基使CA所产生的六元环打开,并形成类型20的β-氧杂环丁烯。随之而来的闭环是[1,2氯原子的迁移完成了该序列。用甲醇处理后,假酰氯1被转化为假酯3和酯4。通过X射线晶体学分析了环戊烯在CA上的3和3∶1和2∶1的环加合物12的结构。