反应详情

To a solution of (R)-3-tert-butoxycarbonylamino-4-(3′-chloro-biphenyl-4-yl)-2-hydroxy-butyric acid methyl ester (220 mg, 0.524 mmol) is added DAST (0.083 mL, 0.629 mmol) at 0° C. The reaction mixture is gradually warmed to room temperature and stirred for 1 h. Additional DAST (0.083 mL, 0.629 mmol) is added and stirred at room temperature for 2 h. The reaction mixture is diluted with EtOAc and washed with saturated NaHCO3 aqueous solution and brine. The organic layer is dried over Na2SO4 and concentrated. The residue is purified by flash column chromatography (silica gel, eluent; heptane/EtOAc=100:0 to 0:100) to give (R)-3-tert-butoxycarbonylamino-4-(3′-chloro-biphenyl-4-yl)-2-fluoro-butyric acid methyl ester (63 mg). HPLC retention time=1.36 minutes (condition B): MS (m+1-Boc)=322. 1H-NMR (400 MHz, CDCl3) δ ppm 1.39 (s, 9 H), 2.84-2.95 (m, 2 H), 3.06 (bs, 0.5 H), 3.69 (s, 3 H), 4.43-4.61 (m, 1 H), 4.72-4.80 (m, 0.5 H), 5.00 (s, 0.5 H), 5.12 (s, 0.5 H), 7.28-7.34 (m, 3 H), 7.37 (t, 1 H, J=7.58 Hz), 7.42-7.47 (m, 1 H), 7.48-7.53 (m, 1 H), 7.55 (t, 1 H, J=2.02 Hz). 19F-NMR (377 MHz, CDCl3) δ ppm −204.18.

1. stirringstirred at room temperature for 2 h
2. washwashed with saturated NaHCO3 aqueous solution and brine
3. dry with materialThe organic layer is dried over Na2SO4
4. concentrationconcentrated
5. customThe residue is purified by flash column chromatography (silica gel, eluent; heptane/EtOAc=100:0 to 0:100)