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

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Reaction Steps

NaH (0.033 g, 1.52 mmole, 90% oil dispersion) was added to a stirred suspension of 2,4,5,6,7-pentachlorobenzimidazole (14) (0.3 g, 1.03 mmole) in dry CH3CN (35 mL) under a N2 atmosphere. The solution was stirred until H2 evolution had ceased and a clear solution was obtained (20 min.). (2-Benzyloxyethoxy)methylchloride (0.31 g, 1.54 mmole) in CH3CN (10 mL) was then added dropwise. The reaction mixture was stirred for an additional 15 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. 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 followed by crystallization from hexane:EtOAc afforded 0.18 g (38.4%) of blocked product: m.p. 95° C.; 1H NMR (CDCl3): d 7.22-7.34 (m, 5H, C6H5), 5.93 (s, 2H, C-1'), 4.47 (s, 2H, CH2C6H5), 3.70-3.73 (m, 2H, C-3'), 3.45-3.57 (m, 2H, C-4'), 1.83 (s, 3H, Ac). Anal. Calcd. for C17H13NCl5O2 : C, 44.88; H, 2.86; N, 6.16. Found: C, 44.95; H, 2.59; N, 6.05.

Provenance & Evidence