To a stirred solution of borane-methyl sulfide complex (587 μl of a 2.0 M solution in THF; 1.18 mmol; 1.3 eq.) in THF (6.0 mL) maintained at 0° C. under nitrogen atmosphere, was added dropwise a solution of tert-butyl 4-{4-[4-(1H-indazol-3-yl)-1H-1,2,3-triazol-1-yl]phenyl}-3,6-dihydropyridine-1(2H)-carboxylate (400 mg; 0.90 mmol; 1.0 eq.) in THF (6.0 mL). The reaction mixture was stirred at RT for 12 h. Further borane-methyl sulfide complex (135 μl of a 2.00 M solution in THF; 0.27 mmol; 0.3 eq.) was added and the reaction mixture was stirred at RT for 1 more hour. The reaction mixture was then cooled down to 0° C. before the dropwise addition of NaOH (3.6 mL) followed by hydrogen peroxide (615 μl). It was then allowed to warm to RT and stir O/N. The reaction mixture was then diluted with water and extracted with DCM (four times). The combined organic phases were washed with brine, dried over magnesium sulfate, filtered and concentrated. Purification by flash chromatography on silica (EtOAc:heptanes, gradient from 90:10 to 40:60) to give the title compound as a white foam (90 mg, 22%). HPLC (max plot) 96.4%; Rt % 4.16 min. UPLC/MS: (MS+) 461.4, (MS−) 459.5.
