反应详情

35 mg of 1-benzyl-3-[(1Z)-1-(methylsulfanyl)prop-1-en-2-yl]-1,3-dihydro-2H-benzimidazol-2-one 1 (0.113 mmol) prepared as described in example 2 were solubilised in a solution of MeOH/H2O 1:1 (2 mL). Then, CF3SO3H (2 mL) was added and the solution refluxed under magnetic stirring. After 3 h, H2O was added (5 mL) and the solution was extracted 3×10 mL of CH2Cl2. The resulting solid was finally chromatographed on silica gel (CH2Cl2/AcOEt 8:2) to yield 1-benzyl-1,3-dihydro-2H-benzimidazol-2-one 2 as a white powder (12 mg, 48%). Mp 194° C. (Iitt. G. Vernin, H. Domlog, C. Siv, J. Metzger, J. Heterocyclic Chem., 18, 85 (1981): 198° C.); Rf=0.23 (CH2Cl2/AcOEt 8:2); 1H NMR (200 MHz, CDCl3) δ=5.11 (2H, s, CH2), 6.84-7.35 (9H, m, Ar), 10.08 (1H, brs, NH).

1. temperaturethe solution refluxed under magnetic stirring
2. extractionthe solution was extracted 3×10 mL of CH2Cl2
3. customThe resulting solid was finally chromatographed on silica gel (CH2Cl2/AcOEt 8:2)