Visible-Light-Mediated 1,2-Acyl Migration: The Reaction of Secondary Enamino Ketones with Singlet Oxygen

Abstract

Secondary enaminones were oxidized by photochemically generated singlet oxygen, followed by nucleophilic addition of alcohol and an unexpected 1,2-acyl migration to afford quaternary amino acid derivatives. An ene-type reaction pathway is proposed. It is distinctively different from the typical [2+2] addition of singlet oxygen to a C=C bond pathway. Singled out: Secondary enaminones were oxidized by photochemically generated singlet oxygen, and subsequent nucleophilic addition of an alcohol and with an 1,2-acyl migration afforded quaternary amino acid derivatives. An ene-type reaction pathway is proposed. It is distinctively different from the typical [2+2] addition of singlet oxygen to a C=C bond.