反应详情

To a solution of (R)-4-biphenyl-4-yl-3-{3-[1-(2-cyano-ethyl)-1H-tetrazol-5-yl]-propionylamino}-butyric acid ethyl ester (137 mg, 0.297 mmol) in DCM (8 mL) at room temperature is added DBU (1.507 mL, 10.00 mmol) and the mixture is stirred at room temperature for 2 hours. The reaction is extracted with DCM. The combined organic layer is washed with saturated NH4Cl, brine and dried over anhydrous sodium sulfate, filtered and concentrated under reduced. The obtained residue is purified by flash chromatography (silica gel, 2% to 10% EtOH/DCM) to give (R)-4-bipheyl-4-yl-3-(3-1H-tetrazol-5-yl-propionylamino)-butyric acid ethyl ester (37 mg). To the obtained ester in EtOH (2 mL) at room temperature is added aqueous 1M NaOH (1 mL, 1.0 mmol) and the mixture is stirred at room temperature for 1 hour. To the reaction is added 1 mL of aqueous 1M HCl to pH=4, and the mixture is purified by reverse phase HPLC [30% to 60% acetonitrile-H2O (0.1% TFA)] to give (R)-4-bipheyl-4-yl-3-(3-1H-tetrazol-5-yl-propionylamino)-butyric acid. HPLC retention time=1.24 minutes (condition C); MS (m+1)=380; 1H NMR (400 MHz, DMSO-d6) δ ppm 2.37 (dd, J=6.7, 2.1 Hz, 2 H), 2.53 (t, J=7.6 Hz, 2 H), 2.69-2.82 (m, 2 H), 3.02 (t, J=7.7 Hz, 2 H), 4.17-4.29 (m, 1 H), 7.22 (d, J=8.3 Hz, 2 H), 7.34 (tt, J=7.3, 1.3 Hz, 1 H), 7.42-7.48 (m, 2 H), 7.57 (d, J=8.3 Hz, 2 H), 7.64 (dd, J=8.2, 1.1 Hz, 2 H), 8.00 (d, J=8.1 Hz, 1 H), 12.21 (br. s., 1 H), 15.92 (br. s., 1 H).

1. customthe mixture is purified by reverse phase HPLC [30% to 60% acetonitrile-H2O (0.1% TFA)]