Side-chain versus nuclear amination of methyl-substituted benzo- and naphtho-quinones

Abstract

Certain partially alkyl-substituted 1,4-benzoquinones, when treated with N-methylcyclohexylamine, undergo amination in the side chain in preference to the quinone nucleus. This unusual order of reactivity may result from the larger steric requirements of this amine compared with those studied hitherto. Significant but less marked variation occurs in the 1,4-naphthoquinone series as well. Preferential side-chain amination of 2,5-dichloro-3,6-dimethyl-1,4-benzoquinone is also observed, contrary to the behaviour of its non-halogenated analogue. Aminated products derived from 2,3-dimethyl-1,4-naphthoquinone are converted into derivatives of 2-hydroxy-1,4-naphthoquinone under remarkably mild conditions.