Some reactions of N-substituted-1,2-dihydropyridines with cyanogen azide. Synthesis of 1,2,3,4-tetrahydropyridylidene-4-cyanamides

Abstract

The reaction of cyanogen azide (2) with several N-substituted-1,2-dihydropyridines (1) was investigated. Reaction of 1,2-dihydropyridines (1a-d) possessing a N-methoxycarbonyl or N-methanesulfonyl substituent with 2 afford a 1:1 mixture of stereoisomers E- and Z-1,2,3,4-tetrahydropyridylidene-4-cyanamides (3 and 4). In contrast, reaction of N-acetyl-2-butyl-1,2-dihydropyridine (1e with 2 gave rise to the unexpected 2,7-diazabicyclo[4.1.0]hept-4-ene (7) and 2-diazo-1,2,3,6-tetrahydropyridylidene-3-cyanamide (9) together with a 1:1 isomeric mixture of 2 compounds derived from 3 and 4. Mechanisms for the formation of 3, 4, 7 and 9 are discussed. [Synthesis of pharmacologically interesting heterocycles is discussed.].