3,4-Dihydro-2H-pyrroles were synthesized fromγ,δ-unsaturated ketone O-acetyloximes by treatment with acetic acid and 1,4-cyclohexadiene in the presence of a catalytic amount of 1,5-naphthalenediol. During the cyclization, syn-anti isomerization of the O-acetyloximes easily occured and so, both stereoisomers of oximes could be employed.
Photochemical radical cyclization of γ,δ-unsaturated ketone oximes to 3,4-dihydro-2H-pyrroles
作者:Mitsuru Kitamura、Yutaka Mori、Koichi Narasaka
DOI:10.1016/j.tetlet.2005.02.062
日期:2005.4
4-Dihydro-2H-pyrroles are synthesized from γ, δ-unsaturated oximes by photochemical radical cyclization with 1,5-dimethoxynaphthalene (DMN) as the sensitizer. The cyclization of alkyl ketone O-acetyloximes proceeds via photosensitized electron transfer in the presence of acetic acid, while conjugated oximes of aryl and α,β-unsaturated ketones are cyclized via energy transfer.