Reactions of substituted phenols with nitrogen dioxide; rearrangements and addition reactions of nitrodienones

Abstract

In this review are discussed the immediate products of the radical coupling of phenoxy radicals with nitrogen dioxide, namely 4-nitrocyclohexa-2,5-dienones and 6-nitrocyclohexa-2,4-dienones. The rearrangements of these nitrodienones are diverse and include (a) the interconversion of 4-nitrocyclohexa-2,5-dienones and 6-nitrocyclohexa-2,4-dienones, (b) the [1,5]-sigmatropic nitro shift in 6-methyl-6-nitrocyclohexa-2,4-dienones with no substituents at C2, (c) the nitro-nitrito interconversion of 4-nitro(nitrito)-cyclohexa-2,5-dienones and 6-nitrocyclohexa-2,4-dienones and (d) the rearrangements of 4-nitrocyclohexa-2,5-dienones in the presence of phenols. Finally, the reactions of 4-nitrocyclohexa-2,5-dienones and 6-nitrocyclohexa-2,4-dienones with nitrogen dioxide are discussed. © Acta Chemica Scandinavica 1998.