Photochemical reactions of quinoxalin-2-ones and related compounds

Abstract

Irradiation of the quinoxalin-2-ones (1a–c, e–g, and i) in the presence of amines gave reductive dimers, the dihydro dimers (3a–c, e–g, and i) of quinoxalin-2-ones, while irradiation of the quinoxalin-2-ones (1d, h, and j), which possess a phenyl group at the 3-position, under similar conditions gave the reduced products, the 3,4-dihydroquinoxalin-2-ones (4d, h, and j). Irradiation of the 1,4-benzoxazin-2-ones (2a–c) in the presence of amines also yielded the reductive dimers, the dihydrodimers (5a–c,) of 1,4-benzoxazin-2-ones. [2 + 2] Photocycloaddition reactions of the quinoxalin-2-ones (1b, c, f, g and k) with electron-poor alkenes were also examined.