反应详情

1.2 g of bromochloromethane (9.2 mmol) were added at room temperature to a solution of 1.0 g of crude 6-Fluoro-1-benzopyran-2-carboxylic acid methyl ester (4.7 mmol) in 15 ml of THF. The solution was then cooled to −80/−85° C. and 4.6 ml of 2.5 M n-BuLi in hexane (9.2 mmol) were slowly added to maintain the internal temperature between −75° C. and −80° C. The reaction progress was monitored by TLC. The solution was then acidified by the addition of 1 ml glacial acetic acid in 2 ml THF between −70° C. and −80° C. 5 ml of water were then added at 0° C. and the aqueous layer was then removed after decantation. The organic layer was concentrated under reduced pressure to give the title compound (1.05 g) as a yellow oil (titration by NMR: ≈80% w/w).

1. additionwere slowly added
2. temperatureto maintain the internal temperature between −75° C. and −80° C
3. customthe aqueous layer was then removed after decantation
4. concentrationThe organic layer was concentrated under reduced pressure