Sodium Carbonate → 6-(2-chloropyridin-3-yl)-1H-benzimidazole

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Reaction Steps

6-(2-Chloropyridin-3-yl)-1H-benzimidazole was synthesized in the similar manner to the preparation of 5-(2-chloropyridin-3-yl)-1H-indazole by heating the mixture of 3-bromo-2-chloropyridine (0.70 g, 3.63 mmol), 1H-benzimidazole-5-boronic acid pinacol ester (0.8 g, 3.27 mmole), Pd(PPh3)4 (330 mg, 0.28 mmol) and 2M aq.Na2CO3 (4 mL, 8 mmol) in 1,4-dioxane (30 mL). Upon extractive work-up with CH2Cl2 and purification of the concentrate by flash silica gel column chromatography (Combiflash® companion System® with RediSep® silica gel column 24 g, 3% MeOH/EtOAc as a eluting solvent upon dry loading the concentrate absorbed on silica gel) provided 6-(2-chloropyridin-3-yl)-1H-benzimidazole (200 mg, 26%). 1H NMR (DMSO-d6): δ 12.57 (s, 1H), 8.95 (dd, 1H, J=1.7 and 4.9 Hz), 8.28 (s, 1H), 7.90 (dd, 1H, J=1.7 and 7.6 Hz), 7.70-7.62 (m, 2H), 7.58 (dd, 1H, J=4.9 and 7.6 Hz), 7.29-7.27 (app s, 1H).LCMS: rt 3.71 min (A), purity 96%, MS (m/e) 230 (MH+).

Provenance & Evidence