Polyhalogenoaromatic compounds. Part XXIV. The reaction of chloropyridyl-lithium compounds with nitriles as a route to triazanaphthalenes

Abstract

The reactions of tetrachloro-4-pyridyl-lithium and tetrachloro-2-pyridyl-lithium with an excess of benzonitrile yield 5,6,8-trichloro-2,4-diphenylpyrido[3,4-d]pyrimidine and 6,7,8-trichloro-2,4-diphenylpyrido[3,2-d]pyrimidine, respectively, via the appropriate n-lithio-imines. The reaction of 2,3,6-trichloro-5-lithio-4-piperidinopyridine with an excess of benzonitrile gives a product formulated as N-[α-(2,5,6-trichloro-4-piperidino-3-pyridyl)benzylidene]-N′-(3,5,6-trichloro-4-piperidino-2-pyridyl)benzamidine.

Tetrachloropyrazine gives methyl- and phenyl-trichloropyrazine on treatment with methyl- and phenyl-lithium, respectively.