反应详情

To a solution of ethyl 2-chlorooxazole-5-carboxylate (510 mg, 2.90 mmol) in anhdryous MeCN (10 mL) and anhydrous MeOH (10 mL) is added NaOMe (628 mg, 11.62 mmol). The crude is stirred at reflux for 2 hrs. To this crude is added additional MeOH. The crude is refluxed for another 4 hrs. The crude is cooled and then concentrated and is redissolved in MeOH (10 mL). To this crude is added 1 N NaOH (10 ml, 10 mmol). The crude is stirred at room temperature for 3 hrs. The crude is quenched with concentrated HCl, PH adjusted to 7 via pH paper indicator. The crude is concentrated to remove MeOH. The crude is diluted in water. The aq. layer is acidified with concentrated HCl and diluted in EtOAc. The organic layer is washed with water, brine, dried over MgSO4, filtered, and concentrated to give 2-methoxyoxazole-5-carboxylic acid (290 mg). This acid is used without further purification. HPLC retention time=0.58 minutes (condition B); MS 144.0 (M+1).

1. temperatureat reflux for 2 hrs
2. temperatureThe crude is refluxed for another 4 hrs
3. temperatureThe crude is cooled
4. concentrationconcentrated
5. dissolutionis redissolved in MeOH (10 mL)
6. stirringThe crude is stirred at room temperature for 3 hrs
7. customThe crude is quenched with concentrated HCl, PH
8. concentrationThe crude is concentrated
9. customto remove MeOH
10. additionThe crude is diluted in water
11. additiondiluted in EtOAc
12. washThe organic layer is washed with water, brine
13. dry with materialdried over MgSO4
14. filtrationfiltered
15. concentrationconcentrated