反应详情

A mixture of ethyl 2-cyano-2-[2-methoxy-3-(o-tolylthio)phenyl]propionate (10 g) and hydriodic acid (58%, 12 ml) in acetic acid (24 ml) was refluxed under heating for 24 hours. After concentration, the residue was dissolved in aqueous sodium hydrogen sulfite and extracted with diethyl ether. The extract was washed with aqueous sodium hydrogen sulfite and water in turn, dried and evaporated under reduced pressure. To the residue was added acetic anhydride (10 ml), and the mixture was refluxed under heating for 10 minutes and evaporated under reduced pressure. The residue was subjected to column chromatography on silica gel (100 g) and eluted with benzene to give oily crude 3-methyl-7-(o-tolylthio)-2,3-dihydrobenzofuran- 2-one (5.4 g). To this product (5.4 g) were added potassium hydroxide (1.5 g) and methanol (50 ml), and the mixture was refluxed under heating for an hour and concentrated under reduced pressure. The residue was crystallized with a mixture of benzene and n-hexane to give 2-[2-hydroxy-3-(o-tolylthio)phenyl]propionic acid (3.85 g), mp. 123°-125° C.

1. temperaturewas refluxed
2. temperatureunder heating for 24 hours
3. concentrationAfter concentration
4. dissolutionthe residue was dissolved in aqueous sodium hydrogen sulfite
5. extractionextracted with diethyl ether
6. washThe extract was washed with aqueous sodium hydrogen sulfite and water in turn
7. customdried
8. customevaporated under reduced pressure
9. additionTo the residue was added acetic anhydride (10 ml)
10. temperaturethe mixture was refluxed
11. temperatureunder heating for 10 minutes
12. customevaporated under reduced pressure
13. washeluted with benzene
14. customto give oily crude 3-methyl-7-(o-tolylthio)-2,3-dihydrobenzofuran- 2-one (5.4 g)
15. temperaturethe mixture was refluxed
16. temperatureunder heating for an hour
17. concentrationconcentrated under reduced pressure
18. customThe residue was crystallized with a mixture of benzene and n-hexane