Photochemical Reactions of Arenecarboxylic Acid Esters with Electron-Rich Alkenes: 2 + 2 Cycloaddition, Hydrogen Abstraction, and Cycloreversion

Article abstract of DOI:10.1021/jo00262a031

The photochemical reaction of arenecarboxylic acid methyl esters and isopropyl esters with alkenes has been examined and found to afford three types of products: (a) 2-alkoxyoxetanes 3 via a direct 2 + 2 cycloaddition to the substrate alkenes; (b) β,γ-unsaturated ketones 5 via hydrogen abstraction by the carbonyl oxygen of the photoexcited ester from an allylic position of the substrate alkene; and (c) alkoxyalkenes 4, which arise via 2 + 2 cycloreversion of the oxetanes 3.The quantum yields for the formation of the various products generally fell in the range 0.005-0.03, approximately 1 order of magnitude less than those of aryl ketones and aldehydes undergoing similar reactions.