Photochemistry of aryloxiranes:free radical 1,2-alkyl migrations in a constrained system

摘要

The photochemistry of 1,2-diaryl oxianes has been described as proceeding through carbon-carbon bond cleavage to form carbonyl ylids while the photochemistry of monoaryl oxiranes has been reported as proceeding via cleavage of the benzyl carbon-oxygen bond to generate 1,3-diradicals.Intermediates such as 2 usually react by cycloaddition or by fragmentation into the corresponding carbonyl compound and an aryl carbene.4 Intermediates such as 4 have been shown to react preferentially through a 1,2-hydrogen shift to form carbonyl compounds.These processes are outlined in Scheme 1.