Into a 100 mL 3-necked round-bottom flask purged and maintained under an inert atmosphere of nitrogen, was placed tert-butyl (3R)-3-[4-amino-3-iodo-1H-pyrazolo[3,4-d]pyrimidin-1-yl]piperidine-1-carboxylate (400 mg, 0.90 mmol, 1.00 equiv), 2-[4-(3,5-difluorophenoxy)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (360 mg, 1.08 mmol, 1.20 equiv), sodium carbonate (190 mg, 1.79 mmol, 1.99 equiv), ethylene glycol dimethyl ether (50 mL), water (15 mL), and Pd(PPh3)4 (52 mg, 0.04 mmol, 0.05 equiv). The resulting solution was stirred for 12 h at 80° C. and then concentrated under vacuum. The residue was loaded onto a silica gel column and eluted with dichloromethane/methanol (100/1) to give 340 mg (72%) of tert-butyl (3R)-3-[4-amino-3-[4-(3,5-difluorophenoxy)phenyl]-1H-pyrazolo[3,4-d]pyrimidin-1-yl]piperidine-1-carboxylate as a yellow solid.
