alkyl-substituted o-benzoquinones in the presence of acetaldehyde gave the corresponding acetylcatechol and catechol monoacetates via the attack of the acetyl radical on the ground-state quinone molecule. In the reaction of 3,5-di-t-butyl- and 3-t-butyl-5-methyl-o-benzoquinones, the dimer of alkyl-substituted cyclopentadienone, generated by the photodecarbonylation of the quinones, was also obtained.