N[C:2]1[S:3][C:4]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[C:5]([C:7]([O:9][CH2:10][CH3:11])=[O:8])[N:6]=1.[N+]([O-])(OCCC(C)C)=O.C(Cl)(Cl)[Cl:28].[OH-].[Na+]>CC#N>[Cl:28][C:2]1[S:3][C:4]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[C:5]([C:7]([O:9][CH2:10][CH3:11])=[O:8])[N:6]=1To a solution of ethyl 2-amino-5-phenylthiazole-4-carboxylate in MeCN was added CuCl2 at 0° C., and the isoamyl nitrate was slowly added dropwise thereto, followed by stirring for 1 hour. To the reaction mixture was added CHCl3, followed by stirring at 0° C. for 2 hours and then at room temperature for 2 hours. The reaction mixture was neutralized by addition of a 1 M aqueous NaOH solution, and filtered through Celite. The filtrate was extracted with EtOAc, and the organic layer was washed with water and brine in this order and then dried over MgSO4. After concentration under reduced pressure, the residue obtained was purified by medium-pressure preparative liquid chromatography (silica gel YAMAZEN YFLC WPrep2XY, hexane:EtOAc) to obtain ethyl 2-chloro-5-phenylthiazole-4-carboxylate as a yellow oil.
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