Regioselective synthesis of 5-azaindazoles based on the intramolecular amination reaction of 5-acyl-4-pyridones with hydrazines

The labile tautomerism of N-unsubstituted 5-acyl-4-pyridones, which exist in the form of 4-pyridone or 4-hydroxypyridine depending on the solvent, has been demonstrated. This equilibrium determines reactivity of pyridones and ability...