The Effects of Triplet Sensitizers' Energies on the Photoreactivity of β,γ‐Unsaturated Methyl Ketones

Abstract

Triplet determines reactivity: β,γ-Unsaturated ketones 1 do not undergo the oxa-di-π-methane (ODPM) rearrangement in the presence of acetophenone or 3-methoxyacetophenone as a triplet sensitizer. However, they afford the ODPM products 2 when using triplet sensitizers with triplet energies slightly higher than those of the alkene triplets. When the triplet energies of the sensitizers are slightly lower than those of the alkene groups in 1, ODPM rearrangement occurs along with 1,3-acyl migration to form enones 3 (see scheme).