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) on an ice bath was added 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (2.2 g, 11 mmol) and 1-hydroxybenzotriazole (1.5 g, 11 mmol) in dichloromethane (50 ml) dropwise and the mixture was stirred at room temperature for 15 hours. The dichloromethane was then distilled off under reduced pressure and the residue was extracted with ethyl acetate (200 ml). The ethyl acetate layer was serially washed with 10% aqueous citric acid solution, saturated aqueous sodium hydrogen carbonate solution, and saturated saline in the order mentioned and dried over anhydrous sodium sulfate. The solvent was then distilled off and the residue was purified by 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. After this colorless oil was dissolved in ethyl acetate (50 ml), 4N HCl/ethyl acetate (50ml) 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 provide 1-((s)-2-amino-3-methyl-1-oxobutyl)-4-(2-chlorophenyl)piperazine hydrochloride (3.32 g, 95.8%) as colorless crystals.

Provenance & Evidence