Synthesis of multi-substituted 4-aminopyridines via ring-opening and recyclization reactions of 2-iminopyridines

Abstract

A novel synthesis of multi-substituted 4-aminopyridines from 2-iminopyridines by a two-step procedure is described. During this transformation, 4-amino-2-iminopyridines undergo a regioselective ring-opening reaction in the presence of KOH in t-butanol to afford 5-oxo-pent-3-enimidamides, which are then converted into 4-aminopyridines in toluene under reflux following a 6π-azaelectrocyclization and N-to-N 1,3-sulfonyl group migration mechanism.