Stability of alkoxy-substituted inden-2-ones and 6,7-dimethoxy-1,4-diphenyl-2,3-naphthoquinone

Abstract

5,6-Dimethoxy-1,3-diphenylinde-2-one 4 and 5,6-dimethoxy-1,3-di-o-tolylinden-2-one 5 have been generated by dehydrobromination of 1-bromo-5,6-dimethoxy-1,3-diarylindan-2-ones. They appear more stable than the corresponding inden-2-ones lacking methoxyl substituents. In particular, 5 fails to dimerise at 20 °C whereas other known inden-2-ones dimerise even at low temperature. 6,7-Dimethoxy-1,4-diphenyl-2,3-naphthoquinone 8 generated by lead tetraacetate oxidation of the corresponding dihydroxynaphthalene appears less persistent than the corresponding quinone lacking methoxyl substituents, perhaps because of easier reaction with the lead tetraacetate.