FC(F)(F)C(O)=O.[CH3:8][NH:9][C:10]1[S:11][C:12]([C:18]2[CH:23]=[CH:22][N:21]=[CH:20][CH:19]=2)=[C:13]([C:15](=O)[NH2:16])[N:14]=1.Cl.C(=O)([O-])[O-].[K+].[K+]>C(Cl)Cl.N1C=CC=CC=1>[C:15]([C:13]1[N:14]=[C:10]([NH:9][CH3:8])[S:11][C:12]=1[C:18]1[CH:23]=[CH:22][N:21]=[CH:20][CH:19]=1)#[N:16]Trifluoroacetic acid (2.8 g) was dropwise added to a suspension of 2-methylamino-4-carbamoyl-5-(4-pyridyl)thiazole (2.1 g) and pyridine (2.8 g) in methylene chloride (60 ml) at 5° to 10° C. with stirring, which was continued under the same condition for 6 hours. The reaction mixture was poured into ice-water and the resultant mixture was acidified to pH 1.0 with 10% hydrochloric acid. The separated aqueous layer was adjusted to pH 7.5 with 20% potassium carbonate and extracted with ethyl acetate. The organic extract was washed with brine and dried over magnesium sulfate. The solvent was removed in vacuo to give a crystalline residue, which was recrystallized from a mixture of ethyl acetate and tetrahydrofuran to afford 4-cyano-2-methylamino-5-(4-pyridyl)thiazole (0.5 g). mp 192°-195° C.
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