反应详情

A 100 mL round bottom flask equipped with a magnetic stirrer was charged with methyl 2-(4-chlorophenyl)benzoxazole-4-carboxylate (0.50 g, 1.74 mmol), THF (10 mL), methanol (10 mL), lithium hydroxide (0.08 g, 3.48 mmol) and water (10 mL). The reaction was stirred at room temperature for 18 hours. After this time, the reaction was diluted with ethyl acetate (50 mL) then acidified to pH 4 with 2 N HCl. The aqueous layer was extracted with ethyl acetate (2×25 mL). The organic layers were then combined and washed with brine (1×25 mL), dried with sodium sulfate, filtered and concentrated to dryness in vacuo to yield 2-(4-chlorophenyl)benzoxazole-4-carboxylic acid (0.43 g, 90% yield) as a white solid: 1H NMR (500 MHz, CDCl3) δ 11.53 (bs, 1H), 8.26 (d, J=8.5 Hz, 2H), 8.18 (d, J=8.0 Hz, 1H), 7.84 (d, J=8.0 Hz, 1H), 7.58 (d, J=8.5 Hz, 2H), 7.55 (t, J=8.0 Hz, 1H); MS (ESI) m/z 274 [M+H]+

1. customA 100 mL round bottom flask equipped with a magnetic stirrer
2. extractionThe aqueous layer was extracted with ethyl acetate (2×25 mL)
3. washwashed with brine (1×25 mL)
4. dry with materialdried with sodium sulfate
5. filtrationfiltered
6. concentrationconcentrated to dryness in vacuo