반응 #6525

반응 방정식

pyrrole-2-carboxylic acid

o-aminophenol

boric acid

→

2-(pyrrol-2-yl)benzoxazole

수율 52.0%

용매

ethyl acetate

xylene

반응 조건

후처리

1. 1
   기타2-(Pyrrol-2-yl)benzoxazole was prepared
2. 2
   온도was heated
3. 3
   온도under reflux for 3 days
4. 4
   기타while removing water which
5. 5
   기타was generated from reaction
6. 6
   기타The cooled reaction mixture
7. 7
   세척washed with 150 mL of 5% sodium hydroxide solution
8. 8
   건조The separated organic layer was dried over anhydrous sodium sulfate
9. 9
   기타The resulting crude product was purified by column chromatography on silica gel with 20% hexane in chloroform as eluant

실험 절차

2-(Pyrrol-2-yl)benzoxazole was prepared as follows: A mixture of 5.55 g (0.05 mol) of pyrrole-2-carboxylic acid and 5.46 g (0.05 mol) of o-aminophenol and 3.09 g (0.05 mol) boric acid in 50 mL of xylene was heated under reflux for 3 days while removing water which was generated from reaction using a Dean-Stark trap. The cooled reaction mixture was diluted with 100 mL of ethyl acetate, washed with 150 mL of 5% sodium hydroxide solution and then with 150 mL of water. The separated organic layer was dried over anhydrous sodium sulfate. The resulting crude product was purified by column chromatography on silica gel with 20% hexane in chloroform as eluant. The desired product, 2-(pyrrol-2-yl)benzoxazole (4.75 g, 52%), was obtained as a white solid. m.p. 149°-150° C.; 1H NMR (CDCl3) δ6.38-6.40 (m, 1H, ArH), 7.05-7.06 (m, 1H, ArH), 7.11-7.13 (m, 1H, ArH), 7.29-7.36 (m, 2H, 2xArH), 7.53-7.56 (m, 1H, ArH), 7.65-7.69 (m, 1H, ArH), 10.9 (bs, 1H, NH).

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