methyl pent-3-ynoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of 4-fluoro-2-(4-methanesulfonyl-phenylethynyl)-benzaldehyde (example 2-1, 3rd step) (2.02 g, 6.68 mmol) and pent-3-ynoic acid methyl ester (3.03 g, 26.8 mmol) in 1,2-dichloroethane (40 mL), was added gold(III) bromide (0.264 g, 1.18 mmol). The resulting mixture was heated at 80° C. for 2 hours before additional gold(III) bromide (0.125 g, 0.59 mmol) was added. Another portion of gold(III) bromide (0.125 g, 0.59 mmol) was added after 2 more hours. After a total of 6 hours of heating, the reaction mixture was cooled to room temperature, and the solvent was removed to afford a brown oil. Flash chromatography (Aspire FlashReady™, 50 μm, 30% ethyl acetate in hexane) gave [6-fluoro-4-(4-methanesulfonyl-benzoyl)-3-methyl-naphthalen-2-yl]-acetic acid methyl ester (87 mg, 3.1%). HRMS (ESI+) cald. for C22H19FO5S [(M+Na)+] 437.0829, obsd. 437.0827. was added After a total of 6 hours of heating the solvent was removed to afford a brown oil