The synthesis of aryl amines enabled by rearrangement and demethylaromatization of cyclohexadienimines.

Abstract

The rearrangement and demethylaromatization of cyclohexadienimines (namely cyclohexadienone imines) were investigated in detail under metal-free conditions. Treating 4-aryl-4-methylcyclohexadienimines with acyl chloride at 100 °C in dichloromethane led to the smooth formation of m-arylaniline derivatives in good to excellent yields, in which [1,2]-migration of the aryl group at C-4 occurred exclusively. The demethylaromatization of 4-aryl-4-methylcyclohexadienimines mediated by iodotriphenylphosphonium iodide (in situ prepared via the reaction of triphenylphosphine with iodine) in toluene at 100 °C proceeded well, generating p-arylanilines in moderate to good yields. An efficient and alternative method for the synthesis of polysubstituted aryl amines, especially m-arylaniline derivatives which are otherwise difficult to synthesize through traditional methods, was developed.