[5C + 1N] Annulation of 2,4-pentadienenitriles with hydroxylamine: a synthetic route to multi-substituted 2-aminopyridines

Abstract

A facile and efficient synthetic route to multi-substituted 2-aminopyridines has been developed via a formal [5C + 1N] annulation of readily available 2,4-pentadienenitriles with hydroxylamine (NH₂OH) under very mild conditions, which involves sequential intermolecular aza-nucleophilic addition of hydroxylamine, intramolecular aza-cyclization, and dehydration reactions.