Short-RInChIKey=SA-FUHFF-UHFFFADPSC-JZSBUPSAIW-UHFFFADPSC-NUHFF-NUHFF-NUHFF-ZZZ

In a vial, ethyl 5-azido-1H-pyrazole-4-carboxylate (50.0 mg, 276 μmol, 1.00 equiv) was dissolved in THF (6.00 mL) and water (6.00 mL) (1:1) and copper;sulfate (8.81 mg, 55.2 μmol, 0.20 equiv), sodium ascorbate (54.7 mg, 276 μmol, 1.00 equiv) and ethynylbenzene (36.6 mg, 39.4 μL, 359 μmol, 1.30 equiv) were added. The reaction mixture was stirred at 70 °C for 48 hours. For work, up the reaction mixture was diluted in water and extracted three times with methylene chloride. The combined organic phases were washed with water and brine, dried over Na2SO4 and filtered.