Ipso Nitration. An Efficient Synthesis of Ipso Nitration Products of Aromatic Hydrocarbons

Ipso nitration products of aromatic hydrocarbons have been synthesized from phenols. Nitration of a number of 4-alkylphenyl acetates gave 4-alkyl-4-nitrocyclohexadienones. Reduction of these nitrodienones with sodium borohydride in methanol gave 4-alkyl-4-nitrocyclohexadienols. These labile nitrodienols were converted to the more easily handled 4-alkyl-4-nitrocyclohexadienyl acetates by low-temperature acylation with acetyl chloride and pyridine. Representative nitrodienyl acetates were synthesized by this three-step sequence in 60% yield from the starting phenyl acetate. The synthesis of l, 4-dimethyl-4-nitrocyclohexadienol from 4-methyl-4-nitrocyclohexadienone illustrates the use of organolithium reagents in 1, 2-addition to the carbonyl center of nitrodienones.