3,3,3-Trifluoropropyne → ethyl 4-trifluoroprop-1-ynylbenzoate

Participants

Reaction Conditions

Reaction Steps

3,3,3-Trifluoro-1-propyne (approx. 0.6 mL, approx. 6 mmol) was condensed in a flame-dried Schlenk tube immersed in a dry ice/acetone bath. Tetrahydrofuran (3 mL) was added followed by a solution of butyllithium in hexanes (2.15 mL, 3.44 mmol, 1.6 M). After stirring 2.5 h at −78° C., zinc chloride (6.87 mL, 3.44 mmol, 0.5 M solution in tetrahydrofuran) was added to the reaction mixture and the reaction vessel was transferred to an ice-water bath and maintained at 0° C. for 30 min. Ethyl 2-ethoxy-4-iodobenzoate (1.00 g, 3.12 mmol, prepared as described in example 14) and tetrakis(triphenylphosphine)palladium(0) (0.18 g, 0.16 mmol) were then added. The reaction vessel was allowed to warm to room temperature and then after 1 h warmed to 50° C. for 18 h. After cooling, the reaction mixture was partitioned between brine (70 mL) and methylene chloride (2×100 mL), dried over magnesium sulfate and evaporated. Purification of the crude residue by flash column chromatography (silica gel, eluting with 1/1 mixture of methylene chloride and hexanes) gave ethyl 4-trifluoroprop-1-ynylbenzoate as an off-white solid (0.474 g, 53%).

Provenance & Evidence