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a) Preparation of intermediate 1b
A solution of 3-chlorofuran-2,4(3H,5H)-dione (74.3 mmol, 1eq.) and thiourea (86.2 mmol, 1.2 eq.) in EtOH (50 mL) was heated at reflux for 4 hrs. Solvent was removed and the residue was dissolved in water with HCl (1M). The aqueous solution was basified with aqueous Na2CO3; the solid formed was filtered, washed with water and dried in vacuo (Y: 73%).
for 4h; Reflux;
Stage #1: 3-chloro-(3H,5H)-furan-2,4-dione; ethanol; thiourea for 4h; Heating / reflux;
Stage #2: With hydrogenchloride In water
Stage #3: With sodium carbonate In water Alkaline aqueous solution;
9 Ethyl 2-amino-4-(hydroxymethyl)-1,3-thiazole-5-carboxylate
Ethyl 2-amino-4-(hydroxymethyl)-1,3-thiazole-5-carboxylate A solution of 5.0 g (37 mmol) of 3-chlorofuran-2,4(3H,5H)-dione and 3.3 g (43 mmol) of thiourea in 50 ml EtOH was heated at reflux for 4 h. Solvent was removed and the residue was dissolved in water with 1N HCl added. The aqueous solution was basified with aqueous Na2CO3. Thick solids that formed were filtered, rinsed with water and dried in vacuo. NMR: 1.2 (t, 3H), 4.2 (q, 2H), 4.6 (s, 2H), 4.9 (br s, 1H), 7.8 (s, 2H).