| 81% |
With sodium hydroxide; In ethanol; at 20℃; |
The thiazole ethyl ester (1.0 g, 5.81 mmol) was treated with 0.5 M ethanolic sodium hydroxide solution (60 mL), overnight at room temperature. The reaction mixture was then cooled in an ice bath, and neutralized with acetic acid. The precipitated acid 2 was filtered, washed with diethyl ether, and dried overnight at 60 C.Yield: 81%; off-white crystals, mp 225-227 C (lit. [31] 223 C). 1HNMR (400 MHz, DMSO-d6): 2.35 (s, 3H, CH3), 7.61 (s, 2H, NH2),12.26(br s, 1H, COOH) ppm. HRMS (ESI): m/z [M H] calcd forC5H7N2O2S 159.1698; found 159.1663. |
| 79% |
With sodium hydroxide; In methanol;Reflux; |
Ethyl 2-amino-4-methyl-1,3-thiazole-5-carboxylate(2) (0.075 M) and sodium hydroxide (0.3 M) in methanol were taken in 50 mL round bottom flask. The solution was refluxed with stirring until the reaction was complete. The clear solution was cooled and neutralized with glacial acetic acid and stirred for 30 min. Precipitate obtained was filtered, washed with water, dried and recrystallized with ethanol. The progress of the reaction and purity of the compound were checked by TLC, using benzene : acetone (8 : 2) as mobile phase. Yield: 79%; m.p.: 160-162C; IR (KBr v max) : 3370, 3055, 1741, 1645, 1492, 1388, 913, 728 cm-1; 1H-NMR (300 MHz, DMSO-d6, δ, ppm): 2.71 (s, 3H, CH3), 5.98 (bs, 2H, D2O exchangeable NH2), 10.71 (bs, 1H, COOH); 13C-NMR (75 MHz, CDCl3, δ, ppm): 13.91, (CH3), 133.59, 147.27, 169.54 (-C=O), 173.49 (-C-NH2, thiazole); ESI-MS: m/z 159.13 (M+H), 181.17 (M+Na); Analysis: calcd. for C5H6N2O2S: C, 37.97; H, 3.82; N, 17.71%; found: 37.93; H, 3.84; N, 17.76%. |
| 75 - 94% |
|
A. To a solution of ethyl 2-amino-4-methylthiazole-5-carboxylate (2.19 g, 11.8 mmol) in a 1 :1 mixture of tetrahydrofuran (20 mL) and water (10 mL) was added sodium hydroxide (1.80 g, 45.0 mmol). The reaction mixture was refluxed for 18 hours and allowed to cool down to ambient temperature. The organic solvent was removed in vacuo. The aqueous solution was acidified with 10% aqueous hydrochloric acid solution. The colorless solid was collected and dried to afford 2-amino-4-methylthiazole-5- carboxylic acid (1.40 g, 75%): 1H NMR (300 MHz, DMSO-J6) δ 11.95 (s, IH), 7.26 (s, 2H), 2.01 (s, 3H); MS (ES+) m/z 159.3 (M + 1).A. A mixture of ethyl 2-amino-4-methylthiazole-5-carboxylate (6.58 g, 35.50 mmol) and NaOH (5.40 g, 135.0 mmol) in tetrahydrofuran (60 mL) and water (30 mL) was heated to reflux overnight. Tetrahydrofuran was removed in vacuo, and the residue was neutralized with 5% hydrochloric acid solution to pH 5~6. The precipitate obtained was collected by filtration and dried to afford the crude 2-amino-4-methylthiazole-5- carboxylic acid (5.20 g, 94%): 1H NMR (300 MHz, DMSO-J6) δ 7.63 (s, 2H), 2.30 (s, 3H); MS (ES+) m/z 159.1 (M + 1). |
|
|
An aqueous solution of 1M-sodium hydroxide (50 ml) was added to an ethanol solution (100 ml) of ethyl 2-amino-4-methylthiazole-5-carboxylate (3.0 g) and the mixture was stirred at room temperature for 26 hours. After distilling off the solvent, acetic acid was added thereto under ice cooling (pH=5). Water was added thereto, the resultant mixture was stirred, and the crystal was collected by filtration. The crystal was washed with water, thereby obtaining 2-amino-4-methyl-thiazole-5-carboxylic acid (2.5 g) as a colorless solid. |
Chemistry
Pharmaceutical Intermediates
Inhibitors/Agonists
Material Science
For Research Only
120K+ Compounds
Competitive Price
1-2 Day Shipping
