A solution of 4-[1-(4-pentafluoroethyloxy-phenyl)-1H-[1,2,4]triazol-3-yl]-benzoic acid (1.67 g, 4.2 mmol), diphenylphosphoryl azide (1.26 g, 4.58 mmol) and triethylamine (0.5 g, 5 mmol) in 10 mL of dry t-BuOH was heated to 75° C. for 90 min, resulting in dissolution of the starting acid and subsequent precipitation of the azide. The cooled solution was then poured onto 10 g of ice, and the resulting mixture was filtered and dried to furnish 0.80 g of the azide as a white solid. 1H NMR (300 MHz, CDCl3) δ 10.1 (s, 1H), 8.65 (s, 1H), 8.40 (d, J=8.4 Hz, 2H), 8.0 (d, J=8.4 Hz, 2H), 7.85 (d, J=9 Hz, 2H), 7.45 (d, J=9 Hz, 2H); ESIMS 399.2 (M+H); mp 175° C. dec.
