反应详情

A mixture of tert-butyl (2-mercapto-benzoimidazol-1-yl)-acetate (Intermediate 3-I, 52 mg, 0.2 mmol), 6-bromo-hexanoic acid ethyl ester (49 mg, 39 μl, 0.22 mmol) and K2CO3 (55 mg, 0.4 mmol) is refluxed in acetone (2 ml) for 5 h and stirred at rt overnight. Evaporation of the solvent in vacuo affords a residue that is purified by flash-chromatography on silica-gel (AcOEt/heptane, 25:75), yielding the title compound (55 mg) in 68% as a colourless oil: tR=7.24 min (LC-1), ESI-MS (pos.): m/z 407.23 [M+H]+, ESI-MS (neg.) 405.22 [M−H]+; 1H-NMR (CDCl3): δ (ppm) 1.25 (t, 3H CH3), 1.44 (s, 9H, tBu), 1.48 (m, 2H), 1.66 (quint., 2H), 1.79 (quint., 2H), 2.30 (t, 2H, CH2C═O), 3.38 (t, 2H, SCH2), 4.10 (q, 2H, OCH2), 4.73 (s, 2H, CH2CO2), 7.17-7.25 (m, 3Harom), 7.69 (m, 1Harom).

1. customEvaporation of the solvent in vacuo
2. customaffords a residue that
3. customis purified by flash-chromatography on silica-gel (AcOEt/heptane, 25:75)