反应详情

2-Amino-thiazole-4-carboxylic acid ethyl ester (38 g) (prepared as described in Example 4) in methanol (400 mL) was cooled in an ice bath and to it was added 25% sodium methoxide over 0.5 hours. The ice bath was removed after 0.5 hours. A small amount of isoluble material was removed by filtration and to the yellow solution was added saturated aqueous ammonium chloride and the reaction mixture concentrated to remove excess methanol. The mixture was basified to pH=9.0 with saturated aqueous sodium bicarbonate and extracted with 1:1 ether/tetrahydrofuran (3×200 mL). The combined organic extracts were washed with water. The organic solution was dried over sodium sulfate and concentrated to give a pale yellow solid which still contained some residual solvent. The solid was suspended in hexanes, filtered on a 5.5 cm funnel then dried in vacuo to give 2-amino-thiazole-4-carboxylic acid methyl ester (15.6 g) as a pale yellow solid.

1. customThe ice bath was removed after 0.5 hours
2. customA small amount of isoluble material was removed by filtration and to the yellow solution
3. additionwas added saturated aqueous ammonium chloride
4. concentrationthe reaction mixture concentrated
5. customto remove excess methanol
6. extractionextracted with 1:1 ether/tetrahydrofuran (3×200 mL)
7. washThe combined organic extracts were washed with water
8. dry with materialThe organic solution was dried over sodium sulfate
9. concentrationconcentrated
10. customto give a pale yellow solid which
11. filtrationfiltered on a 5.5 cm funnel
12. customthen dried in vacuo