反应详情

A mixture of propionic acid (0.8 ml, 10 mol), diphenylphosphoryl azide (2.22 ml, 10.3 mmol) and triethylamine (1.39 ml, 10 mmol) in toluene (15 ml) was refluxed for 90 minutes. The mixture was then cooled to below 40° C., and a solution of ethyl 2-amino-5-(ethoxycarbonyl)-4-methylthiophene-3-carboxylate (1.76 g, 6.85 mmol) in toluene (10 ml) was added, the mixture refluxed for 24 hours. The reaction mixture was diluted with brine, and extracted with ethyl acetate. The organic layer was washed with brine and dried over sodium sulfate. Solvent was removed under reduced pressure, and the residue purified by column chromatography, eluting with ethyl acetate/hexane 1:6 to 1:4, to provide ethyl 5-(ethoxycarbonyl)-2-[(ethylamino)carbonylamino]-4-methylthiophene-3-carboxylate. The structure was confirmed by 1H NMR and mass spectrometry.

1. temperaturewas refluxed for 90 minutes
2. temperatureThe mixture was then cooled to below 40° C.
3. temperaturethe mixture refluxed for 24 hours
4. extractionextracted with ethyl acetate
5. washThe organic layer was washed with brine
6. dry with materialdried over sodium sulfate
7. customSolvent was removed under reduced pressure
8. customthe residue purified by column chromatography
9. washeluting with ethyl acetate/hexane 1:6 to 1:4