Photoinduced electron transfer from enol silyl ethers to quinone .1. Pronounced effects of solvent polarity and added salt on the formation of alpha-enones

被引:17
作者
Bockman, TM [1 ]
Shukla, D [1 ]
Kochi, JK [1 ]
机构
[1] UNIV HOUSTON,DEPT CHEM,HOUSTON,TX 77204
来源
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1996年 / 08期
关键词
D O I
10.1039/p29960001623
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
The enol silyl ethers (ESE) of various ketones are efficiently oxidized to the corresponding alpha,beta-unsaturated enones (E) when a dichloromethane solution containing equimolar amounts of chloranil is irradiated with filtered light (lambda(exc) > 380 nm). The 1:1 adduct (A) of enol silyl ether and quinone is a byproduct, the structure of which is established by X-ray crystallography, Solvent polarity and added salts play a major role in establishing the product distribution between E and A, Such a medium effect, coupled with the ready isomerization of the kinetic-thermodynamic isomers derived from the silylation of 2-methylcyclohexanone, points to the cation radical of the enol silyl ether (ESE(.+)) as the reactive intermediate, A radical-ion pair mechanism involving the rapid one-electron oxidation of enol silyl ethers by photoactivated chloranil is discussed.
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页码:1623 / 1632
页数:10
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