Assembly of N,N-Disubstituted Hydrazines and 1-Aryl-1H-indazoles via Copper-Catalyzed Coupling Reactions

CuI-catalyzed coupling of N-acyl-N′-substituted hydrazines with aryl iodides takes place at 60–90 °C to afford N-acyl-N′,N′-disubstituted hydrazines regioselectively and thereby gives a facile method for assembling N,N-diaryl hydrazines. N-Acyl-N′-substituted hydrazines can also react with 2-bromoarylcarbonylic compounds at 60–125 °C under the catalysis of CuI/4-hydroxy-l-proline to provide 1-aryl-1H-indazoles.