Photochemistry of the carbon–nitrogen double bond. Part 1. Carbon–nitrogen vs. carbon–carbon double bond isomerisation in the photochemistry of α,β-unsaturated oxime ethers: the benzylideneacetone oxime O-methyl ether system

Abstract

The syntheses of the four benzylideneacetone oxime O-methyl ether isomers (2)–(5) are described. Direct or sensitised irradiation of the E,E-isomer (2) or Z,E-isomer (3) leads to equilibration of all four isomers by a combination of rapid carbon–nitrogen double bond isomerisation and slower carbon–carbon double bond isomerisation. A previous investigation of the photochemistry of the E,E-isomer (2) had reported only carbon–carbon double bond isomerisation.