3-Hydroxyanthranilic Acid → 2-p-Tolylbenzoxazole-4-carboxylic acid

To a suspension of 3-hydroxyanthranilic acid (0.153 g, 1 mmol) in toluene (10 mL) was added 4-methylbenzoylchloride (0.464 g, 3 mmol) followed by pyridine (0.275 g, 3.5 mmol) at room temperature. The resulting mixture was stirred at room temperature for 30 minutes then heated to 80C for 1 hr. After this time the reaction was cooled and poured into a mixture of ethyl acetate (50 mL) and 5% aqueous hydrochloric acid (20 mL). Subsequent separation of the layers, drying the organic over MgSO4 and filtration afforded a solution. After removal of the solvent, the residue was dissolved in xylenes (20 mL) and the solution treated with p-TsOH (0.4 g, 2.1 mmol). The reaction mixture was then heated to reflux overnight. After this time the reaction was cooled and poured into water (100 mL), the organic layer separated then washed with water (100 mL). The organic was dried over MgSO4, filtered and concentrated to a solid. Recrystallization of this solid from ethyl acetate gave a white solid product, 2-p-tolylbenzo[d]oxazole-4-carboxylic acid (0.15 g, 60% yield). MS (ESI) m/e 254 [M+H]+.

1. temperatureAfter this time the reaction was cooled
2. customSubsequent separation of the layers
3. customdrying the
4. filtrationorganic over MgSO4 and filtration
5. customafforded a solution
6. customAfter removal of the solvent
7. dissolutionthe residue was dissolved in xylenes (20 mL)
8. temperatureThe reaction mixture was then heated
9. temperatureto reflux overnight
10. temperatureAfter this time the reaction was cooled
11. customthe organic layer separated
12. washthen washed with water (100 mL)
13. dry with materialThe organic was dried over MgSO4
14. filtrationfiltered
15. concentrationconcentrated to a solid
16. customRecrystallization of this solid from ethyl acetate

ORDレコード

ord-077aa96292b24018a811234f39f85d07

出典データセット

uspto-grants-2012_01

DOI

10.6084/m9.figshare.5104873.v1

特許番号

US08088760B2