Palladium-catalyzed oxidation of amine in air: an efficient approach to H-pyrazolo[5,1-a]-isoquinolines

An efficient approach to H-pyrazolo[5,1-a]isoquinolines through a reaction of N′-(2-alkynylbenzylidene)hydrazide with amine in the presence of a cooperative catalysis under mild conditions is reported. The palladium-catalyzed oxidation of amine in air leading to the formation of enamine is the key step during the transformation.