Copper-Catalyzed Tandem O‑Arylation–Oxidative Cross Coupling: Synthesis of Chromone Fused Pyrazoles

Intermolecular tandem copper-catalyzed
O-arylation–oxidative
acylation (cross dehydrogenative coupling-CDC) has been developed
under air as an oxidant. The reaction between 2,4-dihydro-3H-pyrazol-3-ones and ortho-halo aryl carboxaldehydes
furnished the corresponding chromone fused pyrazoles, in a straightforward
manner. The synthetic utility of the presented tandem catalysis has
been demonstrated with the synthesis of an A2-subtype selective
adenosine receptor antagonist in only two steps.