-6alkyl group, which process comprises reacting an aromatic heterocyclic secondary amine of the formula (I):FORMULAwherein A, B, R1 and R3 are as defined above, with an alkylating agent of the formula (II):FORMULA (II)wherein R7 is as defined above, and X is a hydroxyl group, in the presence of a catalyst selected from a rhodium catalyst and a ruthenium catalyst, and a ligand selected from a trial