bromo-2-propynyl-Magnesium synthesis

Yield:-

Reaction Conditions:

mercury dichloride in diethyl ether at 0 - 5; for 1 h;

Steps:

4.A
A 100 mL round bottom flask is charged with magnesium turnings (164 mg, 6.73 mmol) and mercury(II)choride (2.8 mg) and set under nitrogen atmosphere. Ether (1 mL) is added to the solids and the suspension cooled to O⁰C using ice/water bath. Propargyl bromide (1 mL, 6.73 mmol) was added via syringe dropwise maintaining an internal temperature of 5°C. After complete addition, the solution was stirred for 1 hour at 0°C. The cooling bath was removed and the solution warmed to room temperature.After checking if the gridnard reaction was complete (small acetone quench of an liquot and mass spectra analysis to see Grignard reacted to acetone), 2,2-dimethyl-l,3-dioxan-5- one (500 mg, 3.84 mmol) was added dropwise via syringe and the mixture stirred for two hours. The reaction mixture was quenched with sat. aq. NH₄Cl (25 mL) and then extracted with ethyl acetate (50 mL). The organic layer was dried over Na₂SO₄, filtered and the solvent removed under vacuum to afford the crude intermediate.

References:

MERCK & CO., INC. WO2008/85300, 2008, A1 Location in patent:Page/Page column 46-47