Stannane, tributyl(1-ethoxyethenyl)- → methyl 8-acetyl-2-morpholino-4-oxo-4H-chromene-6-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a stirred suspension of methyl 8-bromo-2-morpholino-4-oxo-4H-chromene-6-carboxylate (40 g, 108 mmol, as described in Example 1.00) in dioxane (300 mL) was added tributyl(1-ethoxyvinyl)stannane (38.5 mL, 114 mmol) and bis(triphenylphosphine) palladium (II) chloride (3.05 g, 4.35 mmol). The mixture was purged with nitrogen and heated at 90° C. overnight. More tributyl(1-ethoxyvinyl)stannane (20 mL) and bis(triphenylphosphine) palladium (II) chloride (1.5 g) were added and the reaction mixture heated for an additional 3 hrs. The mixture was cooled to room temperature, HC1-2N (81 mL, 163 mmol) was added and the dark suspension heated at 45° C. for 30 min. The dioxane was evaporated under vacuum, the residue was dissolved in DCM and a saturated solution of sodium bicarbonate was added until pH 4. The organic layer was washed with brine, dried over magnesium sulfate, filtered and concentrated to afford a crude compound which was triturated in diethylether, filtered and dried to afford methyl 8-acetyl-2-morpholino-4-oxo-4H-chromene-6-carboxylate (25.0 g, 69.5%) as an off-white solid.

Provenance & Evidence