Alkoxy-p-quinones

A suspension of 7-methoxy-3-(6-methoxy-3,4-dioxocyclohexa-l,5-dienyl)chromone in 1 1 dioxane-acetone treated with water and some coned. H2SO4, then warmed with stirring until dissolved -> 7-methoxy-3-(4-hydroxy-3,6-dioxocyclohexa-l,4-dienyl)diromone. Y 81%. Also formation of alkoxy-p-quinones ith 0-alkyl migration s. C. A. Weber-Sdiilling and H.-W. Wanzlidc, B. 104, 1518 (1971). 

Without additional reagents o-Alkoxy-p-quinones from p-quinones... 

The nature of the substituents on the allene can have an impact on the outcome of a [2 + 2] cycloaddition reaction, as was illustrated by the Lewis acid catalyzed cycloadditions of l-thioaryl-3,3-dimethylallene (24) and 1 -methyl- 1-trimethylsilylallene to various 2-alkoxy-p-benzoquinones 25 (e.g. equation 8)17. The reactions were considered to proceed via carbocation intermediates formed by nucleophilic attack of the thioallene on the Lewis acid activated quinone. At lower temperatures, these carbocations closed to cyclobutanes 26, whereas at higher temperatures, the thermodynamically more stable benzofurans 27 were formed. 

Shi, Y. Wan, P. Charge polarization in photoexcited alkoxy-suhstituted biphenyls formation of biphenyl quinone methides. J. Chem. Soc., Chem. Commun. 1995, 1217-1218. 

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