Hydrochloric Acid → HCID 69669579, compound

Participants

Reaction Steps

A solution of the crude (3R,4S)-3-amino-1-[N-(tert-butoxycarbonyl)-4-(trifluoromethyl)phenylalanyl]-4-[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl]pyrrolidine-3-carboxylic acid (Step 2, 242 mg) in anhydrous THF (6 mL) under nitrogen was treated with 4 N HCl in 1,4-dioxane (6 mL). After stirring for 2 h at room temperature, 1M aqueous HCl (6 mL) was added and stirring was continued for an additional 1.5 h. The reaction mixture was diluted with water (15 mL) and washed successively with ethyl acetate (25 mL) and methylene chloride (25 mL). The aqueous phase was concentrated and the residue was purified by reverse phase HPLC. Product fractions (mixture of diastereomers) were pooled and concentrated. The residue was reconstituted in 1 M HCl and re-concentrated. The resulting residue was diluted with deionized water and lyophilized to give (3R,4S)-3-amino-4-[3-(dihydroxyboryl)propyl]-1-[4-(trifluoromethyl)phenylalanyl]-pyrrolidine-3-carboxylic acid dihydrochloride (mixture of two diastereomers, each a racemate) (43 mg, 12% overall for 3 steps) as a pale yellow amorphous solid. MS (ESI+) m/z 414 (M−H2O+H+), 396 (M−2H2O+H+); MS (ESI−) m/z 412 (M−H2O−H+).

Provenance & Evidence