Palladium-catalyzed oxidative C-H/C-H cross-coupling of pyrazolo[1,5- a ]azines with five-membered heteroarenes.

The use of Pd(OAc) ₂ as the catalyst and AgOAc as the oxidant enabled the direct regioselective oxidative C-H/C-H cross-coupling of pyrazolo[1,5- a ]pyrimidines or pyrazolo[1,5- a ]pyridines with various five-membered heteroarenes without the need of pre-activation and/or directing groups. Successful coupling partners include thiophenes, benzothiophenes, thiazoles, furans, oxazoles, indoles and imidazo[1,2- a ]pyridines.