Carbon Dioxide → 1,3-Benzoxazole-2-carboxylic acid

Reaktionsgleichung

[O:1]1[C:5]2[CH:6]=[CH:7][CH:8]=[N:9][C:4]=2[CH:3]=[CH:2]1.C([Li])CCC.[C:15](=[O:17])=[O:16]>C1COCC1>[O:1]1[C:5]2[CH:6]=[CH:7][CH:2]=[CH:3][C:4]=2[N:9]=[C:8]1[C:15]([OH:17])=[O:16]

Komponenten

Versuchsvorschrift

Furopyridine (8, 0.71 g, 5.96 mmol) is treated with n-butyl lithium (2.5M in hexane, 2.86 ml, 7.15 mmol) in anhydrous THF (30 ml) at −78° C. After 30 minutes, dry carbon dioxide is passed through the reaction mixture and the temperature is allowed to rise gradually to room temperature in 3 hours. The mixture is concentrated to dryness. The residue is dissolved in water (˜10 ml) and extracted with ethyl acetate. The aqueous layer is acidified to pH˜3 with 1N HCl and kept in the refrigerator over night. The resulting precipitates are filtered and dried to give azabenzofuran carboxylic acid as a white powder (9)