5-azido-3-(pyridin-4-yl)-1-trityl-1H-indazole (1.0 g, 2.1 mmol) and (S)-tert-butyl 3-ethynylpiperidine-1-carboxylate (0.43 g, 2.1 mmol) were suspended in t-BuOH:H2O (1:1 10 mL:10 mL) and then CuSO4.5H2O (5 mg, 0.002 mmol) and Na-Ascorbic acid (40 mg, 0.21 mmol) were added sequentially. Reaction mixture was stirred vigorously at room temperature overnight. After the completion of reaction, added sat. NaCl (30 mL), extracted with EtOAc (3×50 mL), evaporated the organic solvent to give (R)-tert-butyl 3-(1-(3-(pyridin-4-yl)-1-trityl-1H-indazol-5-yl)-1H-1,2,3-triazol-4-yl)piperidine-1-carboxylate (1.26 g) which was used for next step with out purification.
