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.S(=O)(=O)(O)O.N([O-])=O.[Na+].[C:27]([Cu])#[N:28].[C-]#N.[Na+].C([O-])(O)=O.[Na+]>CCOC(C)=O.C(O)(=O)C>[C:27]([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:28]To a mixed solution of ethyl 2-amino-5-phenyl-1,3-thiazole-4-carboxylate, acetic acid, and sulfuric acid was slowly added an aqueous NaNO2 solution (5 mL) at 0° C., followed by stirring at the same temperature for 1 hour. This solution was added to an aqueous solution (40 mL) containing CuCN, NaCN, and NaHCO3 (30 g) over 30 minutes, followed by stirring at the same temperature for 1 hour. EtOAc was added thereto, and the insolubles were filtered through Celite. The filtrate was extracted with EtOAc, the organic layer was dried, and the solvent was removed by evaporation under reduced pressure. The residue was purified by silica gel column chromatography (hexane:EtOAc=from 5:1 to 3:1 to 2:1) to obtain ethyl 2-cyano-5-phenyl-1,3-thiazole-4-carboxylate as a yellow solid.
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