反応 #6525

反応方程式

pyrrole-2-carboxylic acid

o-aminophenol

boric acid

→

2-(pyrrol-2-yl)benzoxazole

収率 52.0%

溶媒

ethyl acetate

xylene

反応条件

後処理

1. 1
   その他2-(Pyrrol-2-yl)benzoxazole was prepared
2. 2
   温度was heated
3. 3
   温度under reflux for 3 days
4. 4
   その他while removing water which
5. 5
   その他was generated from reaction
6. 6
   その他The cooled reaction mixture
7. 7
   洗浄washed with 150 mL of 5% sodium hydroxide solution
8. 8
   乾燥The separated organic layer was dried over anhydrous sodium sulfate
9. 9
   その他The resulting crude product was purified by column chromatography on silica gel with 20% hexane in chloroform as eluant

実験手順

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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