Quinolizines. Part XIII. Rearrangement of quinolizinium-1-diazonium salts into v-triazolo[1,5-a]pyridines

Abstract

A number of 1-aminoquinolizinium salts undergo rearrangement when treated with aqueous nitrous acid to give first the cis-3-(v-triazolo[1,5-a]-pyridyl)acraldehydes; these are readily isomerized to the trans-isomers. The structure of one pair of isomers has been established by oxidation to 3-formyl-v-triazolo[1,5-a]pyridine (12) which has been synthesized. The n.m.r. spectra of the triazolopyridines, and the mechanism of the rearrangement are discussed.