2-(Hydroxymethyl)-1H-benzimidazole → 1-(2-Trimethylsilylethoxymethyl)-2-hydroxymethylbenzimidazole

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a stirred solution of 2-hydroxymethylbenzimidazole (31.94, 0.216 mol) in dry DMF (450 mL) was added N,N-diisopropylethylamine (90 mL, 0.52 mol) followed by 2-(trimethylsily)ethoxymethyl chloride (75% in pentane, 55 g, 0.25 mol) and the mixture heated to 60° C. for 2 h. The mixture was cooled to room temperature, concentrated under reduced pressure and partitioned between EtOAc (400 mL) and distilled water (700 mL). The phases were separated and the aqueous layer extracted with EtOAc (2×200 mL). The combined organic extracts were washed with brine (1×400 mL), dried (Na2SO4), filtered and concentrated under reduced pressure. Purification of the crude oil by column chromatography on silica gel (4% MeOH/CH2Cl2) afforded the desired 1-(2-trimethylsilylethoxymethyl)-2-hydroxymethylbenzimidazole (26.28 g, 44%) as a yellow oil. 1H NMR (CDCl3) δ −0.04 (s, 9H), 0.89 (t, 2H, J=9 Hz), 1.75 (br s, 1H), 3.55 (t, 2H, J=9 Hz), 4.94 (s, 2H), 7.26-7.30 (m, 2H), 7.43-7.45 (m, 1H), 7.70-7.72 (m, 1H).

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