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

In a vial, 3-azido-1-(2-chloro-4-nitrophenyl)-5-methyl-1H-pyrazole (50.0 mg, 179 μmol, 1.00 equiv) was dissolved in THF (4.00 mL) and water (4.00 mL) (1:1) and copper;sulfate (5.73 mg, 35.9 μmol, 0.20 equiv), sodium ascorbate (35.5 mg, 179 μmol, 1.00 equiv) and prop-2-ynyl acetate (22.9 mg, 23.1 μL, 233 μmol, 1.30 equiv) were added. The reaction mixture was stirred at 50 °C for 16 hours, then it was diluted with water and extracted three times with methylene chloride. The combined organic phase was washed with water and brine, dried over Na2SO4 and filtered.