2-[4-(2-Phenyl-[1,3]dioxolan-2-yl)-phenyl]-1H-benzoimidazole-5-carboxylic acid amide. To a solution of 3,4-diamino-benzamide (100 mg, 0.6 mmol) in anhydrous DMF was added 4-(2-phenyl-[1,3]dioxolan-2-yl)-benzaldehyde (168 mg, 0.6 mmol) and sodium metabisulfite (164 mg, 0.86 mmol). The mixture was heated to 90° C. under N2 for 16 h. The reaction mixture was cooled and added dropwise to ice/H2O. The resulting solids were filtered and washed with H2O (59 mL) then hexanes (2×50 mL). Purification by chromatography; (silica gel, 1% 1 methanol saturated with ammonia/9% methanol/CH2Cl2) afforded 160 mg (63%) of the title compound. TLC (silica, 1% methanol-saturated with ammonia/9% methanol/CH2Cl2): Rf=0.3. HPLC (Method A): Rt=7.02. MS (ESI+): mass calculated for C23H19N3O3, 385.1; m/z found, 386.1 [M+H]+. 1H NMR (400 MHz, CD3OD): δ 8.13 (br s, 1H), 8.04 (d, J=8.4 Hz, 2H), 7.77 (d, J=8.5 Hz, 1H), 7.64 (d, J=8.4 Hz, 2H), 7.58 (br s, 1H), 7.49-7.47 (dd, J=8.4. 1.5 Hz, 2H), 7.32-7.23 (m, 3H), 4.03 (s, 4H).
