Hydrochloric Acid → 2-amino-6-borono-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)hexanoic acid dihydrochloride

関与物質

反応手順

An aqueous solution of 2-acetamido-N-tert-butyl-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanamide (0.280 g, 0.527 mmol) in 6M hydrogen chloride (10 mL, 60 mmol) was heated under reflux overnight. The reaction was cooled to room temperature, diluted with 20 mL of water, and washed with ethyl acetate (20 mL). The aqueous layer was purified by HPLC (3 injections) using a 5-20% acetonitrile in water. The fractions corresponding to the desired product were concentrated and lyophilized to give 2-amino-6-borono-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)hexanoic acid dihydrochloride as white powder, which became oily upon exposure to air (hydroscopic). (0.003 g, 2%). 1H NMR (400 MHz, CDCl3, Mixture of diastereoisomers) δ 7.41 (dd, J1=8.1 Hz, J2=6.5 Hz, 2H), 7.12 (t, J=8.1 Hz, 2H), 4.35-4.25 (br, m, 2H), 3.77-3.09 (br. m, 3H), 2.99-2.60 (br. m, 1H), 2.39-1.57 (br. m, 4H), 1.34-1.18 (br. m, 2H), 1.15-1.03 (br. m, 1H), 0.70-0.61 (m, 2H),; ESI MS found for C17H26BFN2O4 m/z 335.3 (M+H-water)+; 351.4 (M−H)−; 333.4 (M−H-water)−.

情報源と証拠