Photochemistry of 4-acyloxy-2-azabuta-1,3-dienes. A novel photochemical 1,2-acyl migration in an enol ester. The synthesis of 2,5-dihydro-oxazole derivatives
Abstract
The facile photorearrangement of 4-acyloxy-2-azabuta-1,3-dienes to novel dihydro-oxazoles is described. For example 4-benzoyloxy-1,1,3,4-tetraphenyl-2-azabuta-1,3-diene (2e) rearranges into 5-benzoyl-2,2,4,5-tetraphenyl-2,5-dihydro-oxazole (3e). It is proposed that the rearrangement occurs via a [1,2]-aroyl migration related to the oxa-di-π-methane process of β,γ-unsaturated ketones.