The general procedure for the synthesis of ethyl propargylate from ethanol and propargylate was as follows: propargylate (310 μL, 5 mmol; Alfa Aesar, Ward Hill, MA; Catalog No. A13245) was dissolved in 13 mL of ethanol to form a colorless solution, followed by the slow addition of concentrated sulfuric acid (139 μL, 2.5 mmol) to this solution. The reaction mixture was heated to reflux for 24 hours. Upon completion of the reaction, the reaction was quenched with 13 mL of water followed by extraction with dichloromethane (10 mL; three times). The organic phases were combined, washed sequentially with water (10 mL; three times) and brine (10 mL), and then dried with anhydrous Na2SO4 (Thermo Fisher Scientific, Pittsburgh, PA; catalog number S421-3). The solvent was removed by distillation under reduced pressure to give the light yellow oily product ethyl propiolate (177 mg, 36% yield). The product was characterized by 1H NMR (400 MHz, CDCl3, δ): 4.26 (q, 3JH-H = 7.1 Hz, CH2, 2H), 2.92 (s, C≡CH, 1H), 1.33 (t, 3JH-H = 7.2 Hz, CH3, 3H).
