反应详情

To a suspension of 5-methoxy-benzofuran-2-carboxylic acid (14 g, 72.8 mmol) in MeOH (600 ml) was added magnesium turnings (10.6 g, 437 mmol) and the mixture was vigorously mechanically stirred for 2 hr keeping the temperature below 30° C. After 2 hr, further magnesium was added (10.6 g, 437 mmol) and the mixture stirred a further 4 hr again maintaining the temperature below 30° C. After 6 hr. the mixture was concentrated to ˜100 ml and distilled H2O (600 ml) was added and the pH adjusted to 1-2 with 1N sulfuric acid. The crude mixture was extracted with EtOAc (2×300 ml) and the combined extracts washed with H2O (200 ml). The combined organic phase was dried with Na2SO4, filtered and evaporated to afford yellowish solid, which was recrystallised from hot toluene (100 ml) to afford white crystals (9.2 g, 47.4 mmol, 65%) Mp. 98-100° C., MS: m/e=194.1 (M+).

1. customthe temperature below 30° C
2. waitAfter 2 hr
3. stirringthe mixture stirred a further 4 hr
4. temperatureagain maintaining the temperature below 30° C
5. waitAfter 6 hr
6. concentrationthe mixture was concentrated to ˜100 ml
7. distillationdistilled H2O (600 ml)
8. additionwas added
9. extractionThe crude mixture was extracted with EtOAc (2×300 ml)
10. washthe combined extracts washed with H2O (200 ml)
11. dry with materialThe combined organic phase was dried with Na2SO4
12. filtrationfiltered
13. customevaporated
14. customto afford yellowish solid, which
15. customwas recrystallised from hot toluene (100 ml)