تفاعل #6525

معادلة التفاعل

pyrrole-2-carboxylic acid

o-aminophenol

boric acid

→

2-(pyrrol-2-yl)benzoxazole

المردود 52.0%

المذيبات

ethyl acetate

xylene

ظروف التفاعل

المعالجة

1. 1
   أخرى2-(Pyrrol-2-yl)benzoxazole was prepared
2. 2
   درجة الحرارةwas heated
3. 3
   درجة الحرارةunder reflux for 3 days
4. 4
   أخرىwhile removing water which
5. 5
   أخرىwas generated from reaction
6. 6
   أخرىThe cooled reaction mixture
7. 7
   غسيلwashed with 150 mL of 5% sodium hydroxide solution
8. 8
   تجفيفThe separated organic layer was dried over anhydrous sodium sulfate
9. 9
   أخرىThe resulting crude product was purified by column chromatography on silica gel with 20% hexane in chloroform as eluant

الإجراء التجريبي

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).

المصدر