Methyl chloroformate → Methyl hept-6-en-2-ynoate

A solution of allylmagnesium bromide (1M, 150 mL, 150 mmol) in ether under a nitrogen atmosphere was cooled to −10° C., and propargyl chloride (5.4 mL, 75 mmol) was added dropwise. The solution was stirred for 24 h at room temperature, and then cooled to 0° C. Methyl chloroformate was added dropwise, and the solution was allowed to stir at room temperature for 4 h. The reaction was quenched by cautious addition of satd aq NH4Cl (100 mL) at 0° C. The organic layer was washed with brine, dried, and evaporated to a residue. Chromatography on silica gel provided the title compound (4.5 g, 44%) as a pale yellow liquid.