反应详情

To 5-cyano-3-methyl-1-benzofuran-2-carboxylic acid (2.58 g) synthesized above in tetrahydrofuran (30 mL) were added oxalyl chloride (1.32 mL) and several drops of N,N-dimethylformamide, and the mixture was stirred at room temperature for 5 hr. The reaction mixture was concentrated under reduced pressure, and the residue was washed with diisopropyl ether to give a pale-brown solid. To a solution (50 mL) of the obtained solid in tetrahydrofuran was added a 1.1M solution (12.0 mL) of lithium tri(isobutoxy)aluminum hydride in tetrahydrofuran at −78° C., and the mixture was stirred at −78° C. for 1.5 hr then at 0° C. for 3 hr. 1N Hydrochloric acid was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure to give a pale-brown solid. To a solution (40 mL) of the obtained solid in tetrahydrofuran was added active manganese dioxide (10.0 g), and the mixture was stirred at 50° C. overnight. Manganese dioxide was filtered off, and the filtrate was concentrated under reduced pressure. The residue was washed with diisopropyl ether to give the title object compound (1.49 g, 63%) as a white solid.

1. concentrationThe reaction mixture was concentrated under reduced pressure
2. washthe residue was washed with diisopropyl ether
3. customto give a pale-brown solid
4. stirringthe mixture was stirred at −78° C. for 1.5 hr
5. waitat 0° C. for 3 hr
6. customto quench
7. customthe reaction
8. extractionthe mixture was extracted with ethyl acetate
9. washThe extract was washed with saturated brine
10. dry with materialdried over magnesium sulfate
11. concentrationconcentrated under reduced pressure
12. customto give a pale-brown solid
13. stirringthe mixture was stirred at 50° C. overnight
14. filtrationManganese dioxide was filtered off
15. concentrationthe filtrate was concentrated under reduced pressure
16. washThe residue was washed with diisopropyl ether