Rapid Access to 3-Aminoindazoles from Nitriles with Hydrazines: A Strategy to Overcome the Basicity Barrier Imparted by Hydrazines

A practical and efficient base mediated synthesis of free 3-aminoindazoles has been developed from reaction of nitriles with hydrazines, which successfully overcomes the difficulty of using aromatic hydrazines as substrates and allows for the synthesis of a wide range of N-aryl substituted free 3-aminoindazoles in moderate to excellent yields under mild conditions in one-pot. This finding provides a rapid and useful strategy for synthesis of various functionalization 3-aminoindazole derivatives.