There are a considerable number of naturally occurring compounds which possess the p- benzoquinone m~ iety.~ An alkenylphenol has recently been shown to be a biosynthetic precursor of ubiquinone.'O It would be of interest to ascertain the role, if any, of the photorearrangement of alkyl-p-benzoquinones to hydroquinones in the biogenesis of naturally occurring quinones. The scope and mechanism of the photorearrangement ...