To a solution of 3-{4-[(2-azidoethyl)amino]-1,2,5-oxadiazol-3-yl}-4-[3-(trifluoromethyl)phenyl]-1,2,4-oxadiazol-5(4H)-one (1.05 g, 2.8 mmol) in methanol (12 mL) was added sodium iodide (2.5 g, 17 mmol). After stirring for 10 minutes, a solution of chlorotrimethylsilane (2.1 mL, 17 mmol) in methanol (1.41 mL) was added dropwise over 15 minutes. The reaction continued to stir for 40 minutes and then a solution of sodium thiosulfate (2.7 g, 17 mmol) in water (12.5 mL) was added in one portion. A beige solid precipitated upon addition of the sodium thiosulfate solution and it was collected by vacuum filtration. The solid was rinsed with water (2×10 mL) and was dried under vacuum overnight to give the desired product. A solid had also precipitated from the filtrate and it was collected by vacuum filtration. After washing with water (3×10 mL) in the funnel, the product was dried overnight under vacuum. The solid was slurry washed with ethyl acetate (3.8 mL) for 1 hour and recollected by filtration. After rinsing with ethyl acetate (2×2 mL) and drying overnight, additional product was obtained. In total, 760 mg of desired product (57%) was obtained as the hydroiodide salt. LCMS calculated for C13H12F3N6O3 (M+H)+: m/z=357.1. 1H NMR (400 MHz, DMSO-d6): δ 8.10 (s, 1H), 7.95 (m, 2H), 7.81 (t, J=8.1 Hz, 1H), 7.68 (br s, 2H), 6.74 (t, J=6.7 Hz, 1H), 3.49 (m, 2H), 3.03 (t, J=6.7 Hz, 2H).
