The Reaction Nitrile Oxides with Alkyl- and Alkyl-halo-substituted p-Benzoquinones

Abstract

Abstract Various aromatic nitrile N-oxides, sterically stabilized and unstabilized ones, were allowed to react with several alkyl- and alkyl-halo-substituted p-benzoquinones with a view to studying the influence of quinone substituents on the mode of the addition reaction. Mono-, di-, and tri-substituted quinones with such substituents gave isoxazoline derivatives formed through addition of nitrile oxides to the C=C bond of the quinones. 2-Chloro-5- and -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.