Photorearrangement of alpha-azoxy ketones and triplet sensitization of azoxy compounds.
Photorearrangement of alpha-azoxy ketones and triplet sensitization of azoxy compounds.
复制标题
α-氧化偶氮酮的光重排和氧化偶氮化合物的三重态敏化。
DOI：
10.1021/jo040274v
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Motten,AnnG
中科院分区：
文献类型：
--
作者：
Engel,PaulS;Tsvaygboym,KonstantinP;Bachilo,Sergei;Smith,WilliamB;Jiang,JinJie;Chignell,ColinF;Motten,AnnG
Although some aspects of azoxy group radical chemistry have been investigated,1unhindered α-azoxy radicals remain poorly understood. Here we report the generation of α-azoxy radicals under mild conditions by irradiation of α-azoxy ketones4a,b. These compounds undergo α-cleavage to yield radicals5a,b, whose oxygen atom then recombines with benzoyl radicals to produce presumed intermediate15. Formal Claisen rearrangement gives α-benzoyloxyazo compounds8a,b, which are themselves photolabile, leading to both radical and ionic decomposition. The ESR spectrum of5awas simulated to extract the isotropic hyperfine splitting constants, which showed its resonance stabilization energy to be exceptionally large. Azoxy compounds have been found for the first time to be good quenchers of triplet excited acetophenone, the main sensitized photoreaction of7Zin benzene being deoxygenation. While this reaction has been reported previously, it was always in hydrogen atom donating solvents, where chemical sensitization occurred. The principal direct irradiation product of4bZand model azoxyalkane7Zis theEisomer, whose thermal reversion toZis much faster than that of previously studied analogues.
