Polyhalogenoaromatic compounds. Part 49. Synthesis of carbolines by the reaction of enamines with tetrachloro-4-cyanopyridine

Abstract

Reactions of tetrachloro-4-cyanopyridine with 1-(dialkylamino)cyclohexenes gave tetrahydro-5H-pyrido[3,2-b]indoles and tetrahydro-9H-pyrido[2,3-b]indoles, in proportions varying with the dialkyl-amino-group. The tetrahydrocarbolines could be dehydrogenated by treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. 2,3-Dichloro-4-cyano-9-ethyl-9H-pyrido[2,3-b]indole was synthesised independently by photolysis of trichloro-4-cyano-6-(N-ethylanilino)pyridine.