Asymmetric epoxidation via phase-transfer catalysis: direct conversion of allylic alcohols into α,β-epoxyketones
作者:Barry Lygo、Daniel C. M. To
DOI:10.1039/b206530d
日期:——
Studies into the use of a chiral phase-transfer catalyst in conjunction with sodium hypochlorite to effect the enantio-selective formation of alpha,beta-epoxyketones from allylicalcohols are described.
A novelsyntheticmethod of ketodiphenylselenonium ylide from alkynylselenonium salt is described. A reaction of alkynylselenonium salt, hydroxide ion, and aldehyde in the presence of silver triflate and triethylamine gave oxiranylketones just as a trans-isomer in moderate to good yields, whereas benzoyl aziridine derivatives were obtained from the reaction with sodium p-toluenesulfonamide instead
It's a trap! Both epoxides and aziridines substituted by an aryl ketone can be reduced efficiently using visible‐light photoredox catalysts. The radicals generated were trapped by allyl sulfones, and formed α‐branched β‐hydroxy or amino derivatives with high diastereocontrol (see scheme; dtbbpy=4,4′‐di‐tert‐butyl‐2,2′‐bipyridine, ppy=2‐phenylpyridine).