76% |
In acetonitrile at 100℃; for 7h; Inert atmosphere; |
4.2.3. 1-(Trimethoxysilyl)propyl-3-(2',6'-diisopropylphenyl)imidazolium bromide (1c)
General procedure: N-(2,6-diisopropylphenyl)imidazole (764 mg, 3.2 mmol) in acetonitrile (20 mL) was added to a dry, round-bottomed flask under an atmosphere of nitrogen. 3-(bromopropyl)trimethoxysilane (684 mg, 3.2 mmol) was added and the mixture heated to 100 °C for 7 h. After cooling to room temperature, the solvent was removed in vacuo and the crude product (now solid) was triturated in diethyl ether (3 × 50 mL) to yield the title compound 1c as an off-white solid (MP: 116-118 °C, 1.17 g, 76%). 1H NMR (400 MHz, CHCl3): 10.30-10.36 (s, 1H, Ar-H), 7.91-7.94 (s, 1H, Ar-H), 7.47-7.55 (m, 1H, Ar-H), 7.25-7.30 (m, 2H, Ar-H), 7.19-7.22 (m, 1H, Ar-H), 4.74-4.81 (t, J = 6.96 Hz, 2H, alkyl-CH2), 3.52-3.57 (s, 9H, O-CH3), 2.19-2.30 (septet, J = 6.96 Hz, 2H, alkyl-CH), 2.04-2.14 (quintet, J = 8.06 Hz, 2H, alkyl-CH2), 0.63-0.69 (t, J = 8.06 Hz, 2H, alkyl-CH2). 13C NMR (100 MHz, CHCl3): 145.4, 138.4, 132.0, 130.2, 124.8, 124.2, 123.2, 52.1, 50.8, 28.8, 24.5, 24.2, 5.6. MS (ES): 391 m/z (M+ - Br). HRMS (EI): calculated for C19H35O3N2Si; 391.2411, found: 391.2401. |