Synthesis
The general procedure for the synthesis of methyl 3-bromopropiolate from methyl propiolate: methyl propiolate (60 g, 713.6 mmol) was dissolved in acetone (2 L), followed by the sequential addition of N-bromosuccinimide (147.22 g, 827.13 mmol) and silver nitrate (12.12 g, 71.37 mmol). A slight exothermic phenomenon was observed during the reaction and the reaction temperature was increased from 21°C to 32°C. The reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the resulting gray suspension was evaporated by vacuum to remove the solvent, pentane (100 mL) was added and filtered through Celite, and the filter cake was washed with additional pentane. The process was repeated twice and all filtrates were combined and vacuum evaporated to give 113 g of methyl 3-bromopropiolate in 98% yield, which contained about 10% unreacted material. The product was characterized by 1H NMR (400 MHz, CDCl3) with a chemical shift δ of 3.78 (s, 3H).
References
[1] Patent: WO2015/166373, 2015, A1. Location in patent: Page/Page column 148
[2] Organic Syntheses, 1997, vol. 74, p. 212 - 212
[3] Synthetic Communications, 1992, vol. 22, # 4, p. 567 - 572
[4] Patent: US2003/236264, 2003, A1. Location in patent: Page 44
[5] Patent: US2003/236270, 2003, A1. Location in patent: Page 33
