Piperazine → 4-Fmoc-Piperazine-2-(R)-carboxylic acid

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Reaction Steps

Piperazine-2(R)-carboxylic acid dihydrochloride (5.95 g) was added to 50 mL dioxane/water (1:1). The solution was cooled in an ice bath and aqueous sodium hydroxide (10% w/v) solution was added drop-wise to adjust the pH to 9˜10. At this pH, piperazine-2-carboxylic acid dissolved completely. Then, Fmoc Chloride (2.46 g) in dioxane was added drop-wise to the ice-cooled solution of piperazine and the reaction mixture was stirred from 0° C. to RT over 5-6 hr. The mixture was poured into 800 ml of ice water and washed once with ether. Then the aqueous phase was acidified to pH 2-3 with 2N of HCl which precipitated a white solid. This solid was filtered and dried in vacuo to obtain 2.46 g of a white powder. MS (ESI pos.): 353 (M+H).

Provenance & Evidence