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Methyl 4-hydroxy-5-(methoxycarbonyl)thiophene-2-carboxylate

sulfuric acid

nitric acid

→

semi-solid

수율 20.0%

Methyl 4-hydroxy-5-(methoxycarbonyl)-3-nitrothiophene-2-carboxylate

수율 20.0%

용매

water

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후처리

1. 1
   workup.ADDITIONThe mixture was poured into ice
2. 2
   추출extracted with ethyl acetate (3×100 mL)
3. 3
   세척The combined organic layer was washed with water, brine
4. 4
   건조dried over sodium sulfate
5. 5
   여과The solution was filtered
6. 6
   기타evaporated the solvent
7. 7
   기타The residue was chromatographed over silica gel column

실험 절차

Methyl 4-hydroxy-5-(methoxycarbonyl)thiophene-2-carboxylate (5 g, 23.14 mmol) was added slowly for 15 min at 0 to −5° C. to concentrated sulfuric acid (25 mL). Then concentrated nitric acid (3.2 mL, 70%, 34.7 mmol) was added to the above reaction mixture for 10 min and stirred at the same temperature for 1 h. The mixture was poured into ice cooled water and extracted with ethyl acetate (3×100 mL). The combined organic layer was washed with water, brine and dried over sodium sulfate. The solution was filtered and evaporated the solvent. The residue was chromatographed over silica gel column using chloroform-methanol (95:5) as eluents to give the product as a yellow color semi-solid (1.2 g, 20%).

출처