Oxidation of nitrobenzylic carbanions with dimethyldioxirane. new synthesis of quinomethanes and nitrobenzylic carbinols. First examples of methylation of carbanions with dimethyldioxirane.

The reaction of nitrobenzylic carbanions with dimethyldioxirane (DMD) results in oxidation at the carbanion center or at the nitronate center to give nitrobenzylic carbinols or quinomethanes, respectively. Minor amounts of the methylation products are also formed. Both of these processes were observed for carbanions of (p-nitroaryl)diarylmethanes. The outcome of the oxidation process is very sensitive to the reaction conditions.

On the mechanism of the dimethyldioxirane oxidation of sigma(H) adducts (Meisenheimer complexes) generated from nitroarenes and carbanions

The mechanism of the novel dimethyldioxirane (DMD) oxidation of sigma(H) adducts (Meisenheimer complexes) generated from nitroarenes and carbanions was elucidated. The proposed mechanism, which is akin to that of the oxidative Nef reaction, is supported by the isolation of the cyclohexadienone intermediate and the lack of a primary kinetic isotopic effect. Protic solvents (H(2)O, MeOH) enhance the reactivity of DMD through intermolecular hydrogen bonding.