C([O:3][C:4]([C:6]1[S:10][C:9]([NH:11][C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13])=[N:8][C:7]=1[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)=O)C.[H-].[Na+].O[NH:28][C:29](=[NH:31])[CH3:30].C(OCC)(=O)C>C1COCC1>[C:15]([O:14][C:12](=[O:13])[NH:11][C:9]1[S:10][C:6]([C:4]2[O:3][N:31]=[C:29]([CH3:30])[N:28]=2)=[C:7]([C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)[N:8]=1)([CH3:17])([CH3:18])[CH3:16]2-Tert-butoxycarbonylamino-4-phenyl-thiazole-5-carboxylic acid ethyl ester (1.9 g 5.6 mmol) was dissolved in dry THF (60 mL). Sodium hydride (60% in oil) and N-hydroxy-acetamidine (0.83 g, 11.2 mmol) dissolved in THF (30 mL) was added. The reaction mixture was heated to reflux over night. The reaction mixture was cooled and ethyl acetate (75 mL) glacial acetic acid (0.43 g) were added. The organic mixture was washed with brine (75 mL). The aqueous phase was extracted with ethylacetate The combined organic phases was washed with brine (50 mL) dried with MgSO4 and solvents were removed in vacuo to give a solid. Yield: 36%.
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