Lewis acid catalysts cause an orientation reversal in the Diels–Alder additions of 2,6-di-methyl-1,4-quinone (1) and toluquinone (12) to 1-substituted 1,3-butadienes and to 1,2- and 1,3-dialkyl dienes. These results are explained by the preferential formation of one reactive quinone–Lewis acid salt.