Flash Photolytic Studies on the Photoconversion of Aryl Vinyl Ethers to Dihydrofurans

Article abstract of DOI:10.1021/jo00318a025

The reaction mechanism of the photocyclization of aryl vinyl ethers was derived from results obtained by means of flash photolysis in the millisecond and submicrosecond time ranges and of steady-irradiation experiments.Decay times, absorption spectra, and quantum yields of intermediates were measured.The reaction proceeds via the excited triplet state of the educts and zwitterionic ground-state intermediates which rearrange bymono-or bimolecular 1,4 hydrogen shifts to yield the products.Some zwitterions also undergo oxygen addition reactions.Several cyclized products polymerize upon reirradiation.The overall reaction is shown to be di stinct but partly analogous to the photocyclization of aryl vinyl sulfides and aromatic enamines.