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

Abstract

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.