Photocycloaddition of quinoxalin-2-ones and benzoxazin-2-ones to aryl alkenes

Abstract

Photocycloadditions of quinoxalin-2-ones and benzoxazin-2-ones to arylalkenes are examined. Irradiation of quinoxalin-2-ones (1) in the presence of arylalkenes (3) such as 1,1-diphenylethylene, styrene, 2- or 4-vinylpyridine, etc, gave the azetidines (4)—(22)via[2 + 2]cycloaddition of the carbon–nitrogen double bond of (1) to the alkene. This photoreaction occurs from the excited triplet state of (1). Benzoxazin-2-ones (2) also added photochemically to arylalkenes to yield the corresponding azetidines (23)—(28).