Abstract 3-Bromo-1-methyl-1, 2, 5, 6-tetrahydropyridine (N− B) borane (7) was prepared from 3-bromopyridine by conversion to 3-bromo-1-methylpyridinium iodide, hydrogenation of the latter with sodium tetrahydroborate and treatment of the resulting 3-bromo-1-methyl-1, 2, 5, 6-tetrahydropyridine (6) with borane− dimethyl sulfide. Whereas no trapping product of the possible intermediate 1-methyl-1-azacyclohexa-2, 3-diene (4) could be observed on ...