反应详情

A solution of ethyl 2′-(acetylamino)-4′-methyl-4,5′-bi-1,3-thiazole-2-carboxylate, Compound (1), (200 mg; 0.64 mmol; 1 eq.) in THF (6 ml) is cooled down to 0° C. Sodium hydroxide (1.60 ml; 5 M; 8.03 mmol; 12.50 eq.) is added dropwise. After 1 h, no starting material can be detected. The mixture is neutralized at 0° C. with HCl 5M solution (1.607 ml; 5 M; 8.03 mmol; 12.50 eq.). The resulting precipitate is filtrated, washed with water and Et2O, affording Compound (4) as white-off powder (137.5 mg; 76%). 1H NMR (DMSO-d6, 300 MHz) δ 2.12 (s, 3H), 2.44 (s, 3H), 7.48 (s, 1H), 12.01 (s, 1H). M− (ESI): 282; M+ (ESI): 284. HPLC (method A), Rt: 1.90 min (purity: 99.50%). Analysis calculated for C10H9N3O3S2 2.0H2O: C, 37.61; H, 4.10; N, 13.16; Exp.: C, 37.73; H, 3.79; N, 13.14. Potassium salt of 2′-(acetylamino)-4′-methyl-4,5′-bi-1,3-thiazole-2-carboxylic acid, Compound (4), is prepared by suspending the parent molecule (90.6 mg; 0.32 mmol; 1 eq.) in THF (3 ml) and water (3 ml). Potassium hydroxide (640 μl; 0.50 M; 0.32 mmol; 1 eq.) is added. The solution is diluted with water, filtered through cotton and lyophylized. The potassium salt of Compound (4) is isolated as white-off solid (104.1 mg; quantitative). 1H NMR (DMSO-d6, 300 MHz) δ 2.12 (s, 3H), 2.44 (s, 3H), 7.48 (s, 1H), 12.01 (br s, 1H). M− (ESI): 282; M+ (ESI): 284. HPLC (method A), Rt: 1.87 min (purity: 99.4%).

1. filtrationThe resulting precipitate is filtrated
2. washwashed with water and Et2O