Light-induced and related reactions of quinones. Part VI. Reactions of some p-quinones carrying formyl groups

Abstract

Preparations of formyl-1,4-benzoquinone, 1,4-benzoquinonylacetaldehyde, 3-(1,4-benzoquinonyl) propionaldehyde, 2-(1,4-benzoquinonyl)-2-methylpropionaldehyde, and 2-methyl-2-(1,4-naphthoquinon-2-yl) propionaldehyde are described. Irradiation of solutions of these quinones in benzene with visible light leads to the isolation of 2,5-dihydroxybenzoic acid from formyl-1,4-benzoquinone, and to the formation of 5-hydroxycoumaran-2-one and 3,4-dihydro-6-hydroxycoumarin from the next two quinones, respectively; the last two quinones in the series lose the elements of formaldehyde, and give 5-hydroxy-3-methylbenzofuran and 5-hydroxy-3-methylnaphtho-[1,2-b]furan, respectively. None of the irradiations proceeded cleanly.