Propargyl bromide → (4RS,5R,6S)-N-[(tert-butyloxy)carbonyl]-6-amino-5-(triisopropylsilyloxy)-7-cyclohexyl-1-heptyn-4-ol

Participants

Reaction Conditions

Reaction Steps

To a solution of magnesium metal (16.4 mmol) and HgCl2 (0.03 g) in Et2O (4 mL) in a flask at room temperature was added several drops of 80% propargyl bromide (16.4 mmol) solution in toluene (1.82 mL) contained in an addition funnel. The mixture turned cloudy. Ether (10 mL) was then added to both the flask and to the propargyl bromide solution in the addition funnel. The funnel solution was added dropwise to the reaction mixture which was cooled to 10° C. The white opaque mixture was stirred for 45 minutes at room temperature after the addition was completed. A solution of the title aldehyde of Step 4 (4.64 mmol) in Et2O (10 mL) was added dropwise to the flask at room temperature. After 2 h at room temperature, the mixture was cooled down to 0° C. and a saturated NH4Cl solution (25 mL) was added. The Et2O layer was collected and the aqueous layer was extracted with Et2O (10 mL). The combined organic layers were washed with water (10 mL), brine (10 mL) and then dried over MgSO4. After evaporation, the residue (a clear, yellow liquid) was purified by medium column chromatography (10% EtOAc in hexane) to give the title alkyne (1.49 g, 66.5% yield). The 1H, 13C and APT NMR spectral data were consistent for the proposed structure.

Provenance & Evidence