Trifluoroacetic acid → 5-(Piperidin-4-yl)-1H-benzo[d]imidazol-2(3H)-one

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Reaction Steps

To a solution of compound 17 (0.95 g, 3 mmol) in a mixture of CH2Cl2 (15 mL) and CH3OH (20 mL) was added trifluoroacetic acid (3 mL) at 0° C., and the mixture was stirred for 6 h at room temperature. Solvents were evaporated under reduced pressure, and triturating with diethyl ether gave the title compound 5. Yield: 90%, light yellow solid, mp 214-215° C. IR (KBr, cm−1) 3238 (CONH), 3043 (Ar—H), 2956 (Alph-H), 1692 (CO), 1612, 1446 (C—C), 1180 (C—N), 1126 (C-0); 1HNMR (500 MHz, DMSO d6) δ 1.73-188 (m, 3H, CH, CH2), 2.77 (m, 2H, CH2), 2.97 (m, 2H, CH2), 3.44 (obscured by H2O, 2H, CH2), 4.46 (m, 1H, CH), 6.74-6.84 (m, 3H, H-4, H-6, H-7), 10.50 (br. s, 1H, NH), 10.54 (br. s, 1H, NH). 13C NMR (125.7 MHz, DMSO d6) δ 30.04 (CH2), 33.37 (CH), 43.86 (CH2), 106.66 (C-4), 118.43 (C-7), 118.94 (C-6), 128.37 (C-8), 129.87 (C-9), 137.24 (C-5), 155.56 (CO). Anal. Calcd for C14H16F3N3O3: C, 50.76; H, 4.87; N, 12.68%. Found: C, 50.70; H, 4.92; N, 12.60%.

Provenance & Evidence