Microwave-induced by-products in the synthesis of 2-

The Letter describes the investigation of an industrial reaction of N-methylphenylpiperazine and chloro nicotinonitrile, under microwave heating. Besides the formation of the expected 2-(4-methyl-2-phe nylpiperazinyl)pyridine-3-carbonitrile (4), extension of the scale leads to unexpected by-products. A specific pathway due to the formation of a reactive ionic alkylating intermediate formed in situ under microwave conditions is proposed to explain the results observed.