[C:1]([C:4]1[S:8][C:7]([NH2:9])=[N:6][C:5]=1[CH3:10])(=[O:3])[CH3:2].N1C=CC=CC=1.[C:17](Cl)(=[O:19])[CH3:18]>C1COCC1.C(Cl)Cl>[C:1]([C:4]1[S:8][C:7]([NH:9][C:17](=[O:19])[CH3:18])=[N:6][C:5]=1[CH3:10])(=[O:3])[CH3:2]5-Acetyl-2-amino-4-methylthiazole (P5) (12.35 g, 79 mmol) is suspended in THF/DCM 3:2 mixture (150 mL). The mixture was cooled down to 0° C. and pyridine (16 mL) is added, followed by the dropwise addition of acetyl chloride (8.43 mL, 119 mmol, 1.5 eq). The mixture was stirred 2 hours at 0° C. As the acetylation is complete, the reaction is quenched with addition of water (70 mL) and diluted with EtOAc (100 mL). The two phases are separated and the organic phase is washed with one portion of 10% citric acid solution. Organic layer is dried over MgSO4, filtrated and evaporated. The resulting crude mass is purified by crystallization in EtOAc/Cyclohexane mixture, to obtain N-(5-acetyl-4-methyl-1,3-thiazol-2-yl)acetamide (P6) as a colorless powder (13.13 g, 83.6% yield). 1H NMR (DMSO-d6) δ: 2.17 (s, 3H), 2.47 (s, 3H), 2.56 (s, 3H), 12.44 (br s, 1H). M− (ESI): 197.3; M+ (ESI): 199.3. HPLC, Rt: 1.7 min (purity: 99.7%).
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