反应详情

温度

120 °C

In a microwave tube, 1-(2-amino-4-methyl-1,3-thiazol-5-yl)-2-bromo ethanone, hydrobromide salt (Intermediate 2)(400 mg; 1.27 mmol; 1 eq.) is suspended in EtOH (7 ml). Ethyl thiooxamate (168.6 mg; 1.27 mmol; 1 eq.) is added and the mixture is heated at 120° C. for 15 min under microwave irradiation. The reaction is complete and a precipitate is formed. It is filtered and washed with EtOH, affording ethyl 2′-amino-4′-methyl-4,5′-bi-1,3-thiazole-2-carboxylate as its hydrobromide salt (201 mg; 45.3%). It is suspended in DCM/EtOH 2:1 mixture (9 ml) and Amberlyst A-21 (200 mg; 4.54 mmol; 3.58 eq.) is added. The mixture is shaken for 2 h30, filtrated and the solvents are evaporated, affording ethyl 2′-amino-4′-methyl-4,5′-bi-1,3-thiazole-2-carboxylate as yellow powder (146.2 mg; 43%). 1H NMR (DMSO-d6, 300 MHz) δ 1.33 (t, J=6 Hz, 3H), 2.32 (s, 3H), 4.38 (q, J=6 Hz, 2H), 7.17 (br s, 2H), 7.82 (s, 1H). M− (ESI): 268.17; M+ (ESI): 270.16. HPLC (method A), Rt: 1.54 min (purity: 99.6%).

1. customa precipitate is formed
2. filtrationIt is filtered
3. washwashed with EtOH