6-chloro-3-(4-fluorophenyl)-1-trityl-1H-pyrazolo[4,3-c]pyridine (Intermediate 4a, 73 mg, 0.147 mmol), (R)-1-(1-phenylethyl)urea (37 mg, 0.225 mmol), Cs2CO3 (120 mg, 0.367 mmol), BrettPhos precatalyst (11.7 mg, 0.015 mmol) and DMA (1.1 mL) were charged in a vial. The mixture was evacuated and purged with nitrogen six times and heated at 100° C. for 55 min. The mixture was diluted with EtOAc and washed with water, brine, dried (Na2SO4) and concentrated to afford a residue, which was purified by chromatography on silica gel (0-100% ethyl acetate in hexane, 20 CV) to afford (R)-1-(3-(4-fluorophenyl)-1-trityl-1H-pyrazolo[4,3-c]pyridin-6-yl)-3-(1-phenylethyl)urea (85 mg, 0.136 mmol, 92%) as a yellow solid. MS ESI calcd. For C40H32FN5O [M+H]+ 618, found 618.
