Preparation Methods and Acylation reaction of Ethyl cyanoglyoxylate-2-oxime

Ethyl cyanoglyoxylate-2-oxime is a white or pale yellow solid at room temperature and pressure. It is insoluble in water but soluble in many organic solvents such as alcohols, ethers, and chlorinated hydrocarbons. Ethyl cyanoglyoxylate-2-oxime is commonly used as an intermediate in chemical synthesis, particularly in the production of other organic compounds. It has widespread applications in the field of pesticides, often serving as a raw material for insecticides, fungicides, and other agrochemicals.

Preparation Methods

Figure1: Preparation Methods of Ethyl cyanoglyoxylate-2-oxime

To a solution of ethyl cyanoacetate (10 g, 88.0 mmol, 1.0 equiv.) dissolved in aqueous acetic acid (45% w/w, 40 mL) at 0°C, the mixture was stirred for 15 minutes to ensure proper cooling and homogenization. Subsequently, sodium nitrite (18.3 g, 265.0 mmol, 3.0 equiv.) was added portion-wise over several minutes to control the exothermic reaction and gas evolution. After the addition was complete, the reaction mixture was allowed to warm gradually to room temperature and stirred continuously for 18 hours to ensure full conversion. Upon completion, the mixture was diluted with diethyl ether (50 mL) and water was added gradually until a clear biphasic solution was obtained, indicating complete dissolution of all solids. The aqueous layer was then extracted twice with diethyl ether to recover the organic-soluble product, and the combined organic extracts were subsequently washed twice with water to remove any residual water-soluble impurities, followed by a single wash with brine to facilitate phase separation and reduce water content. The organic phase was finally dried over anhydrous sodium sulfate to remove any trace amounts of water, and the solvent was removed under reduced pressure to afford the crude product Ethyl cyanoglyoxylate-2-oxime. [1]

Acylation reaction

Figure2: Acylation reaction of Ethyl cyanoglyoxylate-2-oxime

In an oven-dried 5 mL screw-capped glass vial, diisopropylethylamine (1 mmol) was added to a suspension of ethyl Ethyl cyanoglyoxylate-2-oxime (1 mmol) in acetone (2 mL), and the resulting mixture was subsequently cooled to 0°C using an ice bath to ensure low-temperature conditions for the ensuing reaction. Once the desired temperature was reached, 5-chlorothiophene-2-sulfonyl chloride (1 mmol) was introduced dropwise into the reaction mixture to allow for controlled addition and minimize any potential exothermic effects, after which the mixture was stirred continuously. The progress of the reaction was monitored by thin-layer chromatography (TLC), and within 5 to 10 minutes, complete consumption of the starting material was observed alongside the appearance of a new spot, indicating the formation of the desired product. Upon completion of the reaction, the acetone solvent was removed by evaporation under reduced pressure to afford a crude residue, which was then taken up in ethyl acetate for further workup. The organic layer was subsequently washed sequentially with 10% citric acid and a saturated sodium bicarbonate (NaHCO₃) solution to remove any acidic and basic impurities, respectively. The washed organic portion was then dried over anhydrous sodium sulfate (Na₂SO₄) to eliminate any residual water, filtered to separate the drying agent, and finally concentrated using a rotary evaporator to yield the purified product. [2]

Reduction Reaction

The carbon-nitrogen double bond unit in the structure of ethyl cyanoglyoxylate-2-oxime can undergo hydrogenation reduction in the presence of an appropriate reducing agent to yield the corresponding amino derivative. Synthetic procedure: To a stirred solution of ethyl Ethyl cyanoglyoxylate-2-oxime (1.4 g, 10.0 mmol) in water (20.0 mL) was added a saturated aqueous solution of NaHCO₃ (12.0 mL), followed by the portionwise addition of Na₂S₂O₄ (5.2 g, 30.0 mmol). The reaction mixture was then warmed to 35°C and stirred for an additional 2 hours. After this period, NaCl (3.0 g, 50.0 mmol) was added, and the mixture was extracted with DCM. The combined organic layers were washed with brine, dried over Na₂SO₄, filtered, and concentrated in vacuo to afford the product. [3]

Reference

[1] Scharinger, Fabian ; et al, Sterically Demanding Flexible Phosphoric Acids for Constructing Efficient and Multi-Purpose Asymmetric Organocatalysts, Angewandte Chemie, International Edition 2022, 61, e202202189.

[2] Roy, Sayanta ; et al, A New Green Oxyma-Sulfonate Coupling Reagent for Sustainable Organic Transformations, ACS Sustainable Chemistry & Engineering (2025), 13(15), 5531-5545.

[3] Zhou, Renpeng; et al, Rh(III)-Catalyzed, N-Amino-Directed C-H Coupling with α-Cyano-α-Diazoesters for the Synthesis of 3-Aminocinnoline-4-Carboxylates, Journal of Organic Chemistry 2025, 90, 15373-15380.

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