Quinones and quinone-methides—I

Silver oxide or 2,3-dichloro-5,6-dicyanobenzoquinone oxidation of 2-cinnamyl-4,5-methylenedioxyphenol yields a crystalline ortho-quinone methide, which undergoes thermal or acid-catalysed cyclization to 6,7-methylene-dioxyflav-3-ene. Oxidation of 2-(4-methoxybenzyl)-4,5-methylenedioxyphenol yields a crystalline ortho-quinone methide which rapidly dimerises in polar solvents. The structure of the colorless dimer, which is of a type not previously reported, suggests that an ionic reaction is involved in its formation.