Electron-transfer-induced reductive dealkoxylation of alkyl aryl ethers. III. Reductive cleavage of methoxy-substitutedN,N-dimethylanilines (N,N-dimethylanisidines)

The reactivity of the three isomeric methoxy-substituted N,N-dimethylanilines (N,N-dimethylanisidines) and ofN,N-dimethyl-2,6-dimethoxyaniline in the reduction with alkali metals in aprotic solvents was investigated.N,N-Dimethyl-p-methoxyaniline was found to be unreactive, while the other substrates underwent exclusive cleavage of carbon-oxygen bond(s), with the following order of reactivity: 2,6-dimethoxy >o-methoxy >m-methoxy >p-methoxy. Both the relative reactivity and the regioselectivity of cleavage (demethoxylationvs. demethylation) was found to parallel closely that of the corresponding di- and trimethoxysubstituted substrates. These results suggest that intermediates with different electron distribution or even different intermediates are involved in the reductive cleavage of aryl-oxygen and arylnitrogen bonds.