To a solution of 3-(3-iodo-1-tosyl-1H-indol-5-yl)-5-(trichloromethyl)-1,2,4-oxadiazole (600 mg, 1.03 mmol) in DMSO (6 mL) was added isopropyl amine (1.2 mL). The reaction was heated to 90° C. in a sealed tube for 12 h then cooled to RT. The mixture was treated with water and extracted with EtOAc (2×20 mL). The organic layer was dried over anhydrous Na2SO4, and concentrated in vacuo. The residue was purified with basic alumina column chromatography (eluent: 35% EtOAc in petroleum ether) to give 3-(3-iodo-1-tosyl-1H-indol-5-yl)-N-isopropyl-1,2,4-oxadiazol-5-amine (450 mg, 83.3%) as an off brown solid. MS (ESI, pos. ion) m/z: 523.0 (M+1); 1H NMR (400 MHz, DMSO-d6): δ 9.44 (d, J=7.6 Hz, 1H), 8.18 (s, 1H), 8.09-8.07 (m, 1H), 7.96-7.93 (m, 3H), 7.83 (d, J=1.2 Hz, 1H), 7.42 (d, J=8.0 Hz, 1H), 3.88-3.83 (m, 1H), 2.32 (s, 3H), 1.22 (d, J=6.4 Hz, 6H).
