Anomalous transformations of acetaldehyde (2,6-dichloro-4-pyridyl)hydrazone under the conditions of the Fischer reaction

Instead of the usual indolization, when acetaldehyde (2,6-dichloro-4-pyridyl)hydrazone is heated with zinc chloride under the conditions of the Fischer reaction one observes the formation of acetone (2,6-dichloro-4-pyridyl)hydrazone, 1-(2,6-dichloro-4-pyridyl)-5-methylpyrazoline, and 2,6-dichloro-4-aminopyridine, the ratio between which depends on the temperature and duration of the reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 374–377, March, 1973.