Reaktion #6526

Reaktionsgleichung

pyrrole-2-carboxylic acid

2-aminothiophenol

boric acid

→

2-(pyrrol-2-yl)benzothiazole

Ausbeute 14.0%

Lösungsmittel

xylene

ethyl acetate

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwas heated
2. 2
   Temperaturunder reflux for 3 days
3. 3
   Sonstigewhile removing water which
4. 4
   Sonstigewas generated from reaction
5. 5
   Sonstigethe cooled reaction mixture
6. 6
   Waschenwashed with 200 mL of 5% sodium hydroxide solution
7. 7
   TrocknenThe separated organic layer was dried over anhydrous sodium sulfate
8. 8
   SonstigeThe resulting crude product was purified by column chromatography on silica gel with 10% ethyl acetate in hexane as eluant

Vorschrift

A mixture of 5.55 g (50 mmol) of pyrrole-2-carboxylic acid, 6.26 g (50 mmol) of 2-aminothiophenol and 3.09 g (50 mmol) of boric acid in 250 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 200 mL of ethyl acetate, washed with 200 mL of 5% sodium hydroxide solution and then with 200 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 10% ethyl acetate in hexane as eluant. The desired product, 2-(pyrrol-2-yl)benzothiazole (1.40 g, 14%) was obtained as a pale yellow solid. m.p. 150°-151° C.; 1H-NMR (CDCl3) 6.32-6.35 (m, 1H, ArH), 6.87-6.89 (m, 1H, ArH), 6.94-6.96 (m, 1H, ArH), 6.33 (t, 1H, ArH), 6.43 (t, 1H, ArH), 7.84 (d, 1H, ArH), 7.90 (d, 1H, ArH).

Quelle