Selective N-Alkylation of Arylamines with Alkyl Chloride in Ionic Liquids: Scope and Applications

An efficient N-selective alkylation of primary aromatic amines in molten quaternary ammonium salts, as the solvent, under relatively mild and base-free conditions is presented. On the basis of the KamletTaft parameters and the nucleophilicity of the IL (ionic liquid) anions, the influence of the ionic liquid was evaluated. This protocol was validated on a larger multigram scale and with the syntheses of bioactive heterocycles (e.g., 1,4-benzothiazine and quinoxalines) and new efficient MALDI matrixes.