反应详情

A solution of (2R)-2-phenylcarbonyloxypropyl (2S)-2-(tert-butoxycarbonyl)amino-3-(3,4-dihydroxyphenyl)propanoate 2 (6.3 g, 13.7 mmol) in 50 mL of 4N HCl in dioxane was stirred at room temperature for 30 min. The reaction mixture was concentrated to dryness under reduced pressure. The resulting residue was dissolved in about 20 mL of anhydrous acetonitrile and 4 mL of ether. The solution was refrigerated, and the resulting white precipitate was filtered, washed with ether, and dried under vacuum to afford 4.7 g (87% yield) of the hydrochloride salt 3 as a white solid. NMR (400 MHz, CD3OD): δ 1.40 (d, J=6.4 Hz, 3H), 2.99 (dd, J=7.6, 14.4 Hz, 1H), 3.10 (dd, J=5.6, 14.4 Hz, 1H), 4.24 (dd, J=6, 8 Hz, 1H), 4.38 (dd, J=6.8, 11.6 Hz, 1H), 4.52 (dd, J=3.2, 11.6 Hz, 1H), 5.40 (m, 1H), 6.52 (dd, J=2.2, 8.4 Hz, 1H), 6.66 (d, J=2.2 Hz, 1H), 6.69 (d, J=8.2 Hz, 1H), 7.47 (t, J=7.6 Hz, 2H), 7.60 (t, J=7.6 Hz, 1H), 8.02 (d, J=7.6 Hz, 2H). MS (ESI) m/z 360.15 (M+H)+ and 358.09 (M−H)−.

1. concentrationThe reaction mixture was concentrated to dryness under reduced pressure
2. dissolutionThe resulting residue was dissolved in about 20 mL of anhydrous acetonitrile
3. filtrationthe resulting white precipitate was filtered
4. washwashed with ether
5. customdried under vacuum