Quinones and quinone methides. VII. Reactions of 1,4-naphthoquinone and 1,4-benzoquinones with 4-hydroxy-2H-1-benzopyran-2-one and 5,5-dimethylcyclohexane-1,3-dione in acid solutions

Abstract

4-Hydroxy-2H-1-benzopyran-2-one (4) reacts with 1,4-naphthoquinone, 2- methoxy-1,4-benzoquinone and 1,4-benzoquinone in aqueous acetic acid solutions to yield the quinone (6) and the quinols (11)and (2), respectively. With 5,5-dimethylcyclohexane-1,3-dione, 1,4- naphthoquinone forms a bisfurano compound (9) while 1,4-benzoquinone yields the bisfurano compound (18) and the monophenolic furano derivative (17). The blue product formed by acid catalysed dimerization of 2-methoxy-1,4-benzoquinone forms a diacetate, the n.m.r. spectra of which is in accord with structure (15b).