[NH2:1][C:2]1[S:3][CH:4]=[C:5](/[C:7](=[N:13]/[OH:14])/[C:8]([O:10][CH2:11][CH3:12])=[O:9])[N:6]=1.Br[C:16]([CH3:25])([CH3:24])[C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18].C(=O)([O-])[O-].[K+].[K+].O>CN(C)C=O>[NH2:1][C:2]1[S:3][CH:4]=[C:5](/[C:7](=[N:13]/[O:14][C:16]([C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18])([CH3:25])[CH3:24])/[C:8]([O:10][CH2:11][CH3:12])=[O:9])[N:6]=1Ethyl (Z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (32.25 g) of Formula (I) is dissolved in N,N-dimethylformamide (258 ml) at room temperature. Tert.-butyl 2-bromoisobutyrate (38.47 g) and anhydrous potassium carbonate (47.61 g) are added and the resulting suspension is heated to 40-45° C. for 20-25 hrs. The reaction mass is cooled to 30-32° C. and it is added slowly to water. The resulting slurry is stirred at 25-30° C. for about one and a half hours. The product is filtered, washed with water and dried under reduced pressure. Yield: 50 g (93.37%), water content <1.0% w/w; Chromatographic purity (HPLC) >98%.
読み込み中…