Synthesis and reactions of 1-azo-2-azonia-allene salts derived from pyridine derivatives

The 1-aza-2-azonia-allene salts prepared from 3-acetyl- or 3-benzoyl-pyridi ne via the corresponding hydrazone and alpha-chloroaryl-azo derivatives rea ct with propionitrile to afford the corresponding 3-(3-pyridyl)-1,2,4-triaz olium salts. The intramolecular cyclization products could be only isolated as the main products if the intermediate alpha-chlorophenyl-azo derivative s prepared from 4-benzoyl pyridine were treated with SbCl5 in presence or a bsence of propionitrile. Also, only 3-methyl-1,2,3-triazolo[1,5-a]pyridiniu m salts were obtained by reaction of the cumulene prepared from 2-acetyl-py ridine with or without propionitrile in good yields. Treatment of 3-pyridyl indazolium hexachloroantimonates and 3-methyl-1,2,3-triazolo[1,5-a]pyridini um salts with Na2CO3 gave 3-pyridylindazoles and 3-methyl-1,2,3-triazolo[1, 5-a]pyridine.