反应详情

A solution of n-BuLi (36.7 mL, 91.6 mmol) was added dropwise to a solution of 2,4-dibromo-6-fluorobenzoic acid (13.0 g, 43.6 mmol, in 200 mL of THF) at −70° C. The resulting solution was stirred for 15 minutes before CH2O gas (generated by heating 5.1 g of Para formaldehyde to 200° C.) was bubbled into the mixture at −70° C. The suspension was stirred for 1 hour then warmed to room temperature and stirred for another 2 hours. HCl gas was bubbled into the suspension for 15 minutes to give a clear solution. The mixture was diluted with 1 L of EtOAc and washed subsequently with water, saturated Na2CO3 and brine, then dried over anhydrous Na2SO4 and concentrated. The residue was purified by column chromatography (PE:EtOAc=5:1) to give 5-bromo-7-fluoro-2-benzofuran-1(3H)-one as white solid.

1. customwas bubbled into the mixture at −70° C
2. stirringstirred for another 2 hours
3. customHCl gas was bubbled into the suspension for 15 minutes
4. customto give a clear solution
5. washwashed subsequently with water, saturated Na2CO3 and brine
6. dry with materialdried over anhydrous Na2SO4
7. concentrationconcentrated
8. customThe residue was purified by column chromatography (PE:EtOAc=5:1)