PHOTOCHEMICALLY AND THERMALLY INDUCED FREE-RADICAL REACTIONS OF ALPHA,BETA-EPOXY KETONES WITH TRIBUTYLTIN HYDRIDE - SELECTIVE C-ALPHA-O BOND-CLEAVAGE OF OXIRANYLMETHYL RADICALS DERIVED FROM ALPHA,BETA-EPOXY KETONES

被引：51

作者：

HASEGAWA, E ^{[1
]}

ISHIYAMA, K ^{[1
]}

KATO, T ^{[1
]}

HORAGUCHI, T ^{[1
]}

SHIMIZU, T ^{[1
]}

TANAKA, S ^{[1
]}

YAMASHITA, Y ^{[1
]}

机构：

[1] INST MOLEC SCI,OKAZAKI 444,JAPAN

来源：

JOURNAL OF ORGANIC CHEMISTRY | 1992年 / 57卷 / 20期

关键词：

D O I：

10.1021/jo00046a016

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

Free-radical reactions of alpha,beta-epoxy ketones with tributyltin hydride have been studied. These substances were selectively converted to beta-hydroxy ketones under both photochemical and thermal conditions. The photoreaction is initiated by hydrogen abstraction of an epoxy ketone triplet from tributyltin hydride, while azoisbutyronitrile is used as an initiator for the thermal reaction. In general, the photoreaction conditions are particularly useful for aroyl-substituted epoxy ketones while the thermal conditions are applicable to a variety of epoxy ketones. It was also found that the epoxy esters and epoxy alcohols did not undergo the ring-opening reaction under the similar conditions. Tributyltin radical attack on the carbonyl of epoxy ketones is a key process for both the photoreaction and the thermal reaction. Regioselective ring opening of the resulting oxiranylmethyl radical finally produces beta-hydroxy ketones. In order to capture the free-radical intermediates, the reaction of epoxy ketones with allyltributyltin was conducted. The isolation of alpha-allylated beta-hydroxy ketones is interpreted by the involvement of a novel 1,5-tributyltin transfer.

引用

页码：5352 / 5359

页数：8

共 56 条

[1] RADICAL-INDUCED RING-OPENING OF EPOXIDES - A CONVENIENT ALTERNATIVE TO THE WHARTON REARRANGEMENT [J].