Catalytic System for Inhibition of Amination-Type Reaction and Palladium-Catalysed Direct Arylation using Non-Protected Pyrazole Derivatives

The palladium-catalysed direct arylation at C-4 of non-protected 5-aminopyrazoles was found to proceed in high yields using a variety of aryl bromides. The choice of potassium acetate as the base was found to be crucial to inhibit the amination reaction and to promote the direct arylation.