Synthesis of Tetra- and Pentasubstituted Benzenes from Dimedone and Derivatives

Treatment of dimedone (5,5-dimethylcyclohexane-1,3-dione) and derivatives with one molar equivalent of sulfuric acid in trifluoroacetic anhydride leads, via sulfonation and a 1,2-methyl group migration, to a variety of dimethylresorcinol derivatives. The reaction has been performed on substrates bearing ester, alkoxy, halo and amino substituents to produce a variety of polysubstituted benzenes. Transient sulfonated intermediates were observed by NMR.