Synthesis and crystal structure of piperidinium 2‐aryl[1,2,4]triazolo[1,5‐ a ]pyridinides and their neutralization to 2‐aryl[1,2,4]triazolo[1,5‐ a ]pyridines

A one step synthesis of novel piperidinium 2‐aryl[1,2,4]triazolo[1,5‐ a ]pyridinides 6 from 2′‐benzoyl‐2‐cyanoacetohydrazide (2) and α‐substituted cinnamonitriles 3 is described. The reaction takes place by 6‐exodig cyclization followed by an 5‐exo‐trig process to afford salts 6 . The X‐ray diffraction of compound 6a reveal that the cation is strongly linked to the anion by hydrogen bonds and a characteristic partial stacking motive. 2‐Aryl[1,2,4]triazolo[1,5‐ a ]pyridines were obtained from salts 6 by treatment with hydrochloric acid.