A triphenylphosphine mediated photo-rearrangement and methanol addition of aryl chalcones to 1-propanones

Zusammenfassung

Aryl chalcones rearrange and add methanol giving substituted propane-1-ones upon UV-A irradiation in the presence of PPh3. We propose two possible mechanisms for this photo-rearrangement. The reaction involves either the formation of a phosphine-carbonyl intermediate, nucleophilic addition of MeOH and 1, 2 aryl migration or the formation of ylide and carbene intermediates. Intermediates trapped from the reaction mixture support the first mechanistic hypothesis.