1-Hydroxybenzotriazole → HCID 54291569, compound

Participants

Reaction Steps

To a solution of N-tert-butoxycarbonyl-L-valine (2.27 g, 10 mmol) and 1-(2-chlorophenyl)piperazine (2.00 g, 10 mmol) in N,N-dimethylformamide (50 ml) under ice-cooling was dropwise added a solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (2.2 g, 11 mmol) and 1-hydroxybenzotriazole (1.5 g, 11 mmol) in dichloromethane (50 ml), and the reaction mixture was stirred at room temperature for 15 hours. The dichloromethane was then distilled off under reduced pressure and ethyl acetate (200 ml) was added to the residue. The ethyl acetate layer was washed successively with 10 w/v % aqueous citric acid solution, saturated aqueous sodium hydrogen carbonate solution, and saturated brine in the order mentioned and dried over anhydrous sodium sulfate. The solvent was then distilled off and the residue was subjected to silica gel chromatography. Elution with ethyl acetate-n-hexane (1:2, v/v) gave 1,1-dimethylethyl 2-(4-(2-chlorophenyl)piperazinyl)-2-oxo-(s)-1-(2-propyl)ethylcarbamate. This colorless oil was dissolved in ethyl acetate (50 ml), and 4N HCl/ethyl acetate (50 ml) was added dropwise under ice-cooling. The mixture was stirred at room temperature for 3 hours. The reaction product was filtered and washed with ethyl acetate-n-hexane (1:1, v/v) to give 1-((s)-2-amino-3-methyl-1-oxobutyl)-4-(2-chlorophenyl)piperazine hydrochloride (3.32 g, 95.8%) as colorless crystals.

Provenance & Evidence