[C:1]([O:5][C:6](/[CH:8]=[CH:9]/[CH2:10][O:11][N:12]=[C:13]([C:17]1[N:18]=[C:19]([NH:22][CH:23]=[O:24])[S:20][CH:21]=1)[C:14]([OH:16])=[O:15])=[O:7])([CH3:4])([CH3:3])[CH3:2]>C(OCC)(=O)C.C(O)C.[Pd].O>[C:1]([O:5][C:6]([CH2:8][CH2:9][CH2:10][O:11][N:12]=[C:13]([C:17]1[N:18]=[C:19]([NH:22][CH:23]=[O:24])[S:20][CH:21]=1)[C:14]([OH:16])=[O:15])=[O:7])([CH3:4])([CH3:2])[CH3:3]To a solution of 2-(trans-3-tert-butoxycarbonylallyloxyimino)-2-(2-formamidothiazol-4-yl)acetic acid (syn isomer) (8.0 g) in ethyl acetate (60 ml) and ethanol (60 ml) was added 10% palladium on carbon (4.0 g) moistened in water (3 ml) in a stream of nitrogen atmosphere, followed by subjecting to catalytic reduction under atmospheric pressure for 4 hours. After the catalyst was removed by filtration, the filtrate was evaporated. To the residue were added water and ethyl acetate, followed by adjusting to pH 7.5 with a saturated aqueous sodium bicarbonate. The separated aqueous layer was washed with ethyl acetate, and thereto was added ethyl acetate, followed by adjusting to pH 2.0 with 10% hydrochloric acid. The separated organic layer was washed with a saturated aqueous sodium chloride and then dried over magnesium sulfate. Removal of the solvent gave a residue, which was crystallized from n-hexane and collected by filtration to obtain 2-(3-tert-butoxycarbonylpropoxyimino)-2-(2-formamidothiazol-4-yl)acetic acid (syn isomer) (1.80 g).
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