ORTHO-SELECTIVE SIDE-CHAIN NITRATION OF P OLYMETHYLBENZOPHENONES AND ITS APPLICATION TO THE SYNTHESIS OF ANTHRAQUINONES

Polymethylbenzophenones (1a similar to 1j) reacted with fuming nitric acid in acetic anhydride to give 2-(nitromethyl) polymethylbenzophenon es (2a similar to 2j) in satisfactory isolated yields. Compounds 2a si milar to 2d underwent the intramolecular nucleophilic substitution/cyc lization by equimolar amount of 1,8-diazabicy-clo[5.4.0]undec-7-ene an d subsequent oxidation by KMnO4 in MeOH/CH2Cl2 or by Na2Cr2O7 in AcOH to afford the corresponding polysubstituted anthraquinones (3a similar to 3d) in good isolated yields. Compounds 2e similar to 2j underwent the intramolecular vicarious nucleophilic substitution of hydrogen/cyc lization by 2 molar amounts of Na2CO3 in acetone and subsequent oxidat ion by Na2Cr2O7 in AcOH to give the corresponding polysubstituted anth raquinones 3a similar to 3f.