Ethyl chloroformate → Ethyl 5-bromo-3-oxo-2,3-dihydro-1-benzofuran-2-carboxylate

Reaction equation

C(=O)([O-])[O-].[K+].[K+].[Br:7][C:8]1[CH:9]=[CH:10][C:11]2[O:15][CH2:14][C:13](=[O:16])[C:12]=2[CH:17]=1.Cl[C:19]([O:21][CH2:22][CH3:23])=[O:20]>CC(C)=O>[Br:7][C:8]1[CH:9]=[CH:10][C:11]2[O:15][CH:14]([C:19]([O:21][CH2:22][CH3:23])=[O:20])[C:13](=[O:16])[C:12]=2[CH:17]=1

Participants

Procedure

Potassium carbonate (1.66 g, 12 mmol) is added to a solution of 5-bromo-1-benzofuran-3(2H)-one (2.13 g, 10 mmol) in acetone (25 mL). The stirred mixture is treated dropwise with ethyl chloroformate (1.05 mL, 11 mmol). The mixture is then heated at reflux for 18 h. The solids are filtered off and the filtrate concentrated in vacuo. The residue is partitioned between EtOAc and saturated aqueous NaHCO3. The layers are separated and the organic layer washed with brine, dried (Na2SO4), filtered and concentrated in vacuo. The residue is purified by silica gel chromatography (gradient elution with hexanes-EtOAc) to afford the title compound.