Light-induced and related reactions of quinones. Part X. Further studies with hydroxymethyl-, vinyl-, and (2-ethoxycarbonylethyl)-1,4-benzoquinones
Abstract
Irradiation of hydroxymethyl-1,4-benzoquinone in [2H6]benzene gave ([2H5]phenoxymethyl)-1,4-benzoquinone, with no incorporation of deuterium into the quinonoid nucleus. Irradiation of 2-hydroxymethyl-5- and 2-hydroxymethyl-6-methyl-1,4-benzoquinones in benzene gave the corresponding methyl homologues of phenoxymethyl-1,4-benzoquinone, but 3-methyl-2-phenoxymethyl-1,4-benzoquinone was not formed from 2-hydroxymethyl-3-methyl-1,4-benzoquinone.
Irradiation of [3,3,3-2H3]-2-(1,4-benzoquinonyl)propene in benzene gave 3-[2H3]methyl-5-hydroxybenzofuran with neither loss nor scrambling of the label. 1-(1,4-Benzoquinonyl)-1-phenylethylene behaved analogously, but vinyl-1,4-benzoquinone afforded only amorphous material.
Diethyl (1,4-benzoquinonylmethyl)malonate gave ethyl 6-hydroxycoumarin-3-carboxylate when irradiated in benzene containing a trace of oxygen.
The mechanistic significance of these results is discussed.