Microwave-induced by-products in the synthesis of 2-(4-methyl-2-phenylpiperazinyl)pyridine-3-carbonitrile

The Letter describes the investigation of an industrial reaction of N-methylphenylpiperazine and chloronicotinonitrile, under microwave heating. Besides the formation of the expected 2-(4-methyl-2-phenylpiperazinyl)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.

An industrial reaction of N-methylphenylpiperazine and chloronicotinonitrile was investigated under microwave heating.