Theoretical calculations of chemical interactions. Part 4. Aromatic nucleophilic substitutions and S N2 reactions of 4- and 6-substituted 2-nitroanisoles

The reactions of 4-R and 6-R-2nitroanisoles (R =Me, Br) in neat cyclohexylamine and piperidine have been studied. The reactions with cyclohexylamine lead to the respective aromatic nucleophilic substitution products while the reactions with piperidine mainly yield the substituted nitrophenols. It was found that 6-R-2-nitroanisoles react faster than the respective 4-R-2-nitroanisoles. The absence of the expected primary steric effect is thought to be due to the spatial arrangement of the methoxide group which adopts a conformation perpendicular to the ring plane when it is surrounded by two ortho-substituents. CNDO and INDO calculations for different conformations of the substrates give support to this assumption.