[O:1]1[CH2:5][CH2:4][O:3][CH:2]1[C:6]1[S:7][CH:8]=[CH:9][N:10]=1.CCCCCC.C([Li])CCC.[C:22](OCC)(=[O:28])[C:23]([O:25][CH2:26][CH3:27])=[O:24].Cl>O1CCCC1>[O:1]1[CH2:5][CH2:4][O:3][CH:2]1[C:6]1[S:7][C:8]([C:22](=[O:28])[C:23]([O:25][CH2:26][CH3:27])=[O:24])=[CH:9][N:10]=1To a solution of 2-(1,3-dioxolan-2-yl)-1,3-thiazole (14.2 g) in tetrahydrofuran (400 mL) was slowly added a 1.6M n-butyllithium hexane solution (62 mL) at −78° C. The reaction mixture was stirred for 30 min, diethyl oxalate (16.5 g) was added, and the mixture was further stirred for 2 hr. The reaction mixture was warmed to room temperature, 1M hydrochloric acid was added, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated aqueous sodium hydrogen carbonate and saturated brine, dried (MgSO4) and concentrated. The residue was subjected to silica gel column chromatography, and the title compound (12.2 g, yield 52%) was obtained as a pale-yellow oil from a fraction eluted with ethyl acetate-hexane (2:3, volume ratio). MS: 258 (MH+).
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