Friedel-Crafts type methylation with dimethylhalonium salts.

The dimethylchloronium salt [Me2Cl][Al(OTeF5)4] is used to methylate electron-deficient aromatic systems in Friedel-Crafts type reactions as shown by the synthesis of N-methylated cations, such as [MeNC5F5]+, [MeNC5F4I]+ and [MeN3C3F3]+. To gain a better understanding of such fundamental Friedel-Crafts reactions, the role of the dimethylchloronium cation has been evaluated by quantum-chemical calculations.