1,3-Dibromopropane → tert-Butyl 4-(3-bromopropyl)piperazine-1-carboxylate

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Reaction Steps

1,3-Dibromopropane (6.78 mL, 66.8 mmol) is added to a stirred solution of piperazine-1-carboxylic acid tert-butyl ester (4.15 g, 22.2 mmol) and diisopropylethylamine (7.73 mL, 44.4 mmol) in anhydrous 1,4-dioxane (40 mL). The resultant mixture is heated in an oil bath at 90° C. for 20 hours. At ambient temperature ethyl acetate (160 mL) and half-saturated aqueous sodium bicarbonate (NaHCO3) (120 mL) are added to the mixture. The organic layer is separated, dried over magnesium sulfate, filtered, and concentrated. The crude oil is subjected to chromatography on silica gel and eluted with 2 M NH3/MeOH in dichloromethane 0-3% to provide the title compound as a dark oil (4.80 g, 70% yield).

Provenance & Evidence