C([O:3][C:4](=[O:20])[CH:5]([NH:9][C:10](=[O:19])[C:11]1[CH:16]=[CH:15][C:14]([O:17][CH3:18])=[CH:13][CH:12]=1)[CH2:6][CH:7]=[CH2:8])C.[OH-].[Na+]>C1COCC1.CCO>[CH3:18][O:17][C:14]1[CH:13]=[CH:12][C:11]([C:10]([NH:9][CH:5]([CH2:6][CH:7]=[CH2:8])[C:4]([OH:20])=[O:3])=[O:19])=[CH:16][CH:15]=110.56 g of the above prepared 2-(4-methoxy-benzoylamino)-pent-4-enoic acid ethyl ester (38.1 mmol) was dissolved in 120 ml of THF/EtOH=1/1 and treated at 0° with 38 ml of 2N NaOH. The reaction mixture was kept at this temperature for 3 h. It was then poured onto crashed ice/HCl, extracted twice with AcOEt, washed with brine, and dried over natrium sulfate. Evaporation of the solvents, followed by crystallisation from AcOEt at −20°, yielded 8.41 g of the title acid as white crystals of m.p. 121-124°.
読み込み中…