Hydrochloric Acid → 4-(1-(2-(1H-tetrazol-1-yl)ethyl)-1H-benzimidazol-2-yl)[1,4]diazepane

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Reaction Steps

Combine 1-(t-butoxycarbonyl)-4-(1-(2-(1H-tetrazol-1-yl)ethyl)-1H-benzimidazol-2-yl)[1,4]diazepane (2.06 g) and methanol (15 mL). Add a solution of hydrochloric acid in dioxane (4 mL, 4 M, 16 mmol) and stir. After 4 hours, add a 1 M aqueous solution of sodium hydroxide until the pH is about 14. Concentrate in vacuo to remove most of the methanol and then extract 5 times with dichloromethane. Dry the combined organic layers over Na2SO4, filter, and concentrate in vacuo to give a residue. Chromatograph the residue on silica gel eluting with 10% methanol/dichloromethane/0.5% concentrated aqueous ammonia to give 4-(1-(2-(1H-tetrazol-1-yl)ethyl)-1H-benzimidazol-2-yl)[1,4]diazepane: Rf=0.30 (silica gel, 10% methanol/dichloromethane/0.5% concentrated aqueous ammonia).

Provenance & Evidence