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The reaction of 3,6-di-tert-butyl-o-benzoquinone with dimedone in the presence of a catalytic amount of Et3N occurs as repeated 1,4-nucleophilic addition--oxidation and isomerization of a tricyclic quinone into qulnomethane. The intermediate products were isolated and characterized. Semiquinone complexes of quinones were studied by ESR in solution.

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1997 quinols quinols (benzene compounds) Q 0400 -097Functionalized Derivatives of Hindered o-Quinones and Catechols. 3,6-Di-tert-butyl-4-dicyanomethyl-1,2-benzoquinone and Its Isomers.-Base-mediated reaction of di-tert-butylbenzoquinone (I) with malononitrile occurs mainly as 1,4-addition to furnish the title pyrocatechine (III) in good yield. Compound (III) is oxidized to the benzoquinone (IV) in apolar solvents, while in polar solvents the generated benzoquinone is unstable and undergoes a subsequent rearrangement to form the quinomethide (V), which anew rearranges to afford compound (VI) by acidic catalysis. -(ABAKUMOV, G. A.; NEVODCHIKOV, V. I.; ZAITOVA, N. V.; DRUZHKOV, N. O.; ABAKUMOVA, L. G.; KURSKII, YU. A.; CHERKASOV, V. K.; Izv.