-6-methyl-p-benzoquinones gave two kinds of C=C adducts, one formed through the addition to the C=C of methyl-substituted side and the other to that of chlorine-substituted side, and the latter adducts were not isolable due to the prompt dehydrochlorination forming the fully-conjugated isoxazoloquinones and subsequent C=O addition of another nitrile N-oxide forming spirodioxazole derivatives.
The Reactions of Nitrile Oxide–Quinone Cycloadducts. I. Base-Induced Rearrangement of the 1 : 1 –C=C– Adducts of Aromatic Nitrile Oxides with Dialkyl-Substituted<i>p</i>-Benzoquinones
cycloadducts, 9-aryl-7-oxa-8-azabicyclo[4.3.0]nona-3,8-diene-2,5-diones, which were obtainedfrom the reactions of aromatic nitrile oxides with dialkyl-substituted p-benzoquinones, underwent an interesting rearrangement on the action of bases. The reactions exhibited incomprehensible substituent effect. The structure elucidation of the rearranged products and the reaction mechanism are described and discussed