A 100 mL round bottom flask was charged with tert-butyl 4-(5-bromoimidazo[1,2-a]pyrazin-8-yl)piperazine-1-carboxylate (1.0 g, 2.62 mmol), thiophen-2-ylboronic acid (0.50 g, 3.93 mmol), Pd(PPh3)2Cl2 (200 mg, 0.26 mmol), Cs2CO3 (0.60 g, 3.93 mmol) and DMF (30 mL). After air was purged by bubbling N2 into the reaction solution, the reaction mixture was heated at 90° C. for 30 h. Work-up: the reaction mixture was poured into water (150 mL) and extracted with EtOAc (200 mL×3). The combined organic layers were dried over anhydrous Na2SO4 and then concentrated in vacuo. The residue was further purified by flash column chromatography on silica gel with 10% EtOAc in petroleum ether, to afford 0.70 g (72%) of the product as a yellow solid. MS m/z: 386 (M+H+).
