O1[C:5]2([CH2:10][CH2:9][N:8]([C:11]3[CH:18]=[CH:17][C:14]([C:15]#[N:16])=[CH:13][CH:12]=3)[CH2:7][CH2:6]2)[O:4]CC1.OS(O)(=O)=O.CCOC(C)=O>C1COCC1.O>[O:4]=[C:5]1[CH2:6][CH2:7][N:8]([C:11]2[CH:18]=[CH:17][C:14]([C:15]#[N:16])=[CH:13][CH:12]=2)[CH2:9][CH2:10]1To 4-(1,4-dioxa-8-aza-spiro[4.5]dec-8-yl)-benzonitrile (460 mg, 1.88 mmol, reference example 117) dissolved in THF (2 mL) was added 10% H2SO4 (4 mL) and the reaction was stirred for 24 h at room temperature. TLC (40% EtOAc in hexanes) shows a small amount of starting material, but mainly a more polar product. The reaction was diluted with water, extracted with dichloromethane (3×), washed with saturated aqueous NaCl solution, dried with Na2SO4, filtered and evaporated. The crude product was chromatographed on silica gel (20-40% EtOAc in hexanes) to afford the title compound (315 mg, 84%). 1H NMR (CDCl3): δ 7.52 (d, 2H), 6.88 (d, 2H), 3.72 (t, 4H), 2.57 (t, 4H). MS (ion spray) m/z 200 (M+).
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