CS(O[CH:6]1[CH2:9][N:8]([C:10]2[S:11][CH:12]=[C:13]([C:15](=[O:23])[NH:16][C:17]3[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=3)[N:14]=2)[CH2:7]1)(=O)=O.[C:24]([O-:27])(=[S:26])[CH3:25].[K+]>CN(C)C=O>[C:24]([S:26][CH:6]1[CH2:7][N:8]([C:10]2[S:11][CH:12]=[C:13]([C:15](=[O:23])[NH:16][C:17]3[CH:18]=[CH:19][CH:20]=[CH:21][CH:22]=3)[N:14]=2)[CH2:9]1)(=[O:27])[CH3:25]To a solution of 3-methanesulfonyloxy-1-(4-phenylcarbamoyl-1,3-thiazol-2-yl)azetidine (1.28 g, 3.85 mmol) (obtained as described in Reference Example 32(3)) in dimethylformamide (40 ml) was added potassium thioacetate (2.60 g, 23.1 mmol) at room temperature. The mixture was stirred in an oil bath (90° C.) for 3 hours. After checking the completion of the reaction, the reaction mixture was partitioned between ethyl acetate and 10% aqueous sodium chloride solution. The organic layer was washed successively with saturated aqueous sodium hydrogencarbonate solution and saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by chromatography on a silica gel column using hexane:ethyl acetate (1:2) as the eluant to afford 3-acetylthio-1-(4-phenylcarbamoyl-1,3-thiazol-2-yl)azetidine (893 mg, yield 70%) as a pale brown solid.
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