Selective N(1)-arylation of benzotriazole with activated aryl halides under conditions of phase transfer catalysis

Arylation of 1H-1,2,3-benzotriazole with activated aryl halides in a medium of aromatic hydrocarbons under conditions of phase transfer catalysis with the use of inorganic bases and cetyltrimethylammonium bromide as a phase-transfer catalyst was studied. Arylation affords both N(1)- and N(2)-arylation products. Their ratio depends on the nature of the base and the reactivity of the arylating agent. In the presence of catalytic amounts of copper phenylcyclopropanecarboxylate, arylation proceeds regioselectively at the N(1) atom.