Synthesis of 4-aryl(hetaryl)pyrazolo[1,5-a]pyrazines by palladium-catalyzed Suzuki-Miyaura cross coupling

4-Bromopyrazolo[1,5-a]pyrazines react with aryl(hetaryl)boronic acids in the presence of catalytic amounts of Pd(dppf)Cl-2 center dot CH2Cl2 and an excess of Cs2CO3 in the MeCN-H2O, 9:1 solvent system with the formation of 4-aryl(hetaryl)pyrazolo[1,5-a]pyrazines.