Sodium Bicarbonate → (R)-1-(4-trifluoromethoxy-benzenesulfonyl)-piperazine-2-carboxylic acid 4-propyl-benzylamide

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Reaction Steps

To a solution of the compound (6.65 g) obtained in Example 783, Step 2,4-propylbenzylamine (3.26 g) and 1-hydroxybenzotriazole hydrate (2.69 g) in N,N-dimethylformamide (33 ml) was added, with stirring under ice-cooling, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (3.37 g). After stirring overnight at room temperature, saturated aqueous sodium hydrogen carbonate solution and water were added under ice-cooling, and the mixture was stirred at room temperature. The precipitated solid was collected by filtration, washed with water, and dried under reduced pressure to give a crude product (7.40 g). This was purified by silica gel column chromatography (ethyl acetate:n-hexane=1:2) to give a crude product containing (R)-3-(4-propyl-benzylcarbamoyl)-4-(4-trifluoromethoxy-benzenesulfonyl)-piperazine-1-carboxylic acid tert-butyl ester as a main component. The obtained crude product was dissolved in 1,4-dioxane (40 ml), 4N hydrogen chloride/1,4-dioxane solution (50 ml) was added at room temperature, and the mixture was stirred at room temperature for 2 hr. Further, 4N hydrogen chloride/1,4-dioxane solution (20 ml) was added, and the mixture was stirred at room temperature for 1 hr. The reaction mixture was concentrated under reduced pressure, and the residue was partitioned by adding saturated aqueous sodium hydrogen carbonate solution and ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous sodium carbonate, filtrated, and concentrated under reduced pressure to give a crude product (3.70 g) containing the title compound as a main component. The residue was crystallized from a mixed solvent of diisopropyl ether and n-hexane, and collected by filtration. The obtained crude crystals were suspended in diisopropyl ether, collected by filtration and dried to give the title compound (3.0 g).

Provenance & Evidence