Photocycloaddition of 1,1-diphenylethylene to 2,3-dihydropyran

Abstract

1,1-Diphenylethylene reacts with 2,3-dihydropyran on photolysis to yield two allylic addition products as well as cycloaddition product. The triplet state of 1,1-diphenylethylene is implicated in these reactions. The cycloaddition reaction is stereoselective and is thought to result from bond polarization of the reactants.