A mixture of tert-butyl N-tert-butoxycarbonyl-N-[5-(4-ethylsulfonylpiperazin-1-yl)-3-ethynyl-pyrazin-2-yl]carbamate (50 mg, 0.1009 mmol) and 4-Azidoaniline hydrochloride (17.32 mg, 0.1009 mmol) were suspended in t-BuOH (1 mL)/Water (1.000 mL). The reaction was treated with (+)-Sodium L-ascorbate (1.999 mg, 0.01009 mmol) followed by CuSO4.5H2O (0.2519 mg, 0.1103 μL, 0.001009 mmol) and the mixture allowed to stir at ambient temperature for 16 hours. The reaction was treated with DIPEA (13.04 mg, 17.57 μL, 0.1009 mmol) and allowed to heat to 40° C. for 5 hours and then cooled to ambient temperature. The mixture was partitioned between EtOAc/NaHCO3 and the aqueous layer extracted with EtOAc (2×), dried (MgSO4), filtered and concentrated. The material was used crude in the next step (quantitative yield assumed). MS (ES+) 630.00
