Sodium hydride → 2,4,5,6,7-Pentachloro-1-(2-acetoxyethoxymethyl)benzimidazole

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Reaction Steps

NaH (0.12 g, 3.0 mmole, 60% oil disperson) was added to a stirred suspension of 2,4,5,6,7-pentachlorobenzimidazole (14) (1.0 g, 3.4 mmole) in dry CH3CN (120 mL) under a N2 atmosphere. The solution was stirred until H2 evolution has ceased and a clear solution was obtained (20 min.). (2-Acetoxyethoxy) methyl bromide (0.68 g, 10.66 mmole) in CH3CN (34 mL) was then added dropwise. The reaction mixture was stirred for an additional 3 hr. The resulting mixture was concentrated under reduced pressure, diluted with H2O (50 mL), extracted with EtOAc (100 mL), washed with H2O (100 mL), dried (anhyd. Na2SO4) and the solvent was removed under reduced pressure to yield an oil (165). The resulting oil was purified by flash column chromatography (2×24 cm) (230-400 mesh). Elution of the column with hexane:EtOAc (6:4, v/v) and evaporation of the appropriate fractions gave a solid which was recrystallized from MeOH to afford 1.39 g (72%) of 165: m.p. 119° C. 1H NMR (CDCl3): d 5.93 (s, 2H, C-1'), 4.143.92 (m, 4H, C-3' and C-4'), 1.83 (s, 3H, Ac). Anal. Calcd. for C12H9N2Cl5O3 : C,35.45; H, 2.23; N, 6.89. Found: C, 35.57; H, 2.17; N, 16.91.

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