Diethyl Ether → methyl 8-bromo-2-morpholino-4-oxo-4H-chromene-6-carboxylate

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Reaction Steps

To a stirred solution methyl 3-acetyl-5-bromo-4-hydroxybenzoate (106 g, 388 mmol) in toluene (1 L) was added dropwise (diethyloxonio)trifluoroborate (0.201 L, 1630 mmol), under nitrogen. The resulting solution was left to stir overnight at room temperature, then 4-(dichloromethylene)morpholin-4-ium chloride (143 g, 698 mmol) was added and mixture heated at 90° C. for 12 h. Upon cooling to room temperature, ether (1.5 L) was added and the solid was collected by filtration. This solid was then suspended in MeOH (1 L) and the mixture was heated at 50° C. for 2 h. Upon cooling to room temperature, the solid was collected by filtration then solubilized in DCM (1 L) and washed with water and a saturated solution of sodium bicarbonate. The organic layer was dried over MgSO4, filtered and evaporated to dryness to afford methyl 8-bromo-2-morpholino-4-oxo-4H-chromene-6-carboxylate (68.0 g, 47.6%) as an off-white solid. Mass Spectrum: m/z [M+H]+=368.

Provenance & Evidence