To a solution of 3-(3-(6-isopropoxypyrazin-2-yl)-1-tosyl-1H-indol-5-yl)-1,2,4-oxadiazol-5-amine (150 mg, 0.30 mmol) in 1,4-dioxane (1.5 mL) was added 10% aq NaOH (0.75 mL) and the reaction was heated at 100° C. for 2 h. The mixture was cooled to RT and treated with ice cold water (1.5 mL). The precipitate was collected through filtration and the crude product was purified with preparative HPLC (eluent: 30-70% AcCN in H2O with 0.01% TFA) to give 3-(3-(6-isopropoxypyrazin-2-yl)-1H-indol-5-yl)-1,2,4-oxadiazol-5-amine (35 mg, 34%). MS (ESI, pos. ion) m/z: 337.1 (M+1); 1H NMR (400 MHz, DMSO-d6): δ 11.75 (s, 1H), 9.10 (s, 1H), 8.72 (s, 1H), 8.37 (d, J=2.8 Hz, 1H), 7.94 (s, 1H), 7.77-7.71 (m, 3H), 7.56 (d, J=8.4 Hz, 1H), 5.51-5.48 (m, 1H), 1.49 (d, J=6.4 Hz, 6H).
