Potassium Carbonate → 10-Chloro-7-(1-ethylpropyl)-2,3,4,5-tetrahydro-1H-[1,3]diazepino[1,2-a]benzimidazole

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Reaction Steps

To a solution of 4-[2-amino-4-chloro-7-(1-ethylpropyl)-1H-benzimidazol-1-yl]butan-1-ol (3.40 g, 10.8 mmol) in pyridine (50 mL) was added methanesulfonyl chloride (2.60 mL, 32.9 mmol) dropwise at 0° C. After stirring for 1 hr, aqueous sodium bicarbonate was added to the mixture, which was extracted with ethyl acetate. Organic layer was washed with 2N hydrochloric acid, water and brine, dried over sodium sulfate and concentrated in vacuo. The residue was dissolved in N,N-dimethylformamide (100 mL) and potassium carbonate (4.50 g, 32.9 mmol) was added. The mixture was stirred at 110° C. for 15 hr. After cooling, the mixture was diluted with ethyl acetate, washed with water and brine, dried over sodium sulfate and concentrated in vacuo. The residue was purified by flash chromatography on silica gel eluting with a 30-100% ethyl acetate/n-hexane gradient mixture. The filtrate was concentrated in vacuo to give the title compound (1.51 g, 5.17 mmol, 47%) as a pale yellow solid.

Provenance & Evidence