Synthesis
Example 1: Preparation of ethyl 2-oxime cyanoacetate
To a suspension of ethyl cyanoacetate (1.0 kg, 8.84 mol) and sodium nitrite (0.735 kg, 10.65 mol) in water (0.80 L) was slowly added acetic acid (0.70 kg, 11.66 mol), and the reaction temperature was controlled to be in the range of 0-50°C. The reaction temperature was slowly raised to 23-27 °C over a period of 1 h and the reaction mixture was continuously stirred at this temperature for 1 h. The reaction temperature was then adjusted to the temperature of the reaction mixture. After confirming complete consumption of ethyl cyanoacetate by TLC or GC monitoring, the reaction mixture was extracted with ethyl acetate (5 x 1.5 L). The organic layers were combined and washed sequentially with 10% sodium bicarbonate solution (2 x 1.25 L) and saturated brine (1.25 L). The organic layer was dried over anhydrous sodium sulfate and filtered through a hyflow bed. The solvent was removed by distillation under reduced pressure at 40-45 °C. The resulting solid was stirred with cyclohexane (3.0 L) at 25-30 °C for 30 min, filtered and dried in vacuum at 40-45 °C to give ethyl 2-oxime cyanoacetate 1.14 kg (91.2% yield) with 99.82% HPLC purity.
References
[1] Chemistry - A European Journal, 2015, vol. 21, # 16, p. 6090 - 6099
[2] Synthesis, 1999, # 1, p. 46 - 48
[3] Patent: WO2010/140168, 2010, A1. Location in patent: Page/Page column 14
[4] PLoS ONE, 2014, vol. 9, # 10,
[5] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 1, p. 553 - 557
