Synthesis of 1,2,4‐Triazolo[4,3‐<i>a</i>]pyridines and Related Heterocycles by Sequential Condensation and Iodine‐Mediated Oxidative Cyclization

Abstract

A facile and efficient approach to access 1,2,4-triazolo[4,3-a]pyridines and related heterocycles has been accomplished through condensation of readily available aryl hydrazines with corresponding aldehydes followed by iodine-mediated oxidative cyclization. This transition-metal-free synthetic process is broadly applicable to a variety of aromatic, aliphatic, and α,β-unsaturated aldehydes, and can be conveniently conducted on the gram scale.