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Electrochemical Oxidative Cleavage of Alkynes to Carboxylic Acids

Qingyuan Feng, Yamin Wang, Binnan Zheng and Shenlin Huang*

*International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China, Email:

Q. Feng, Y. Wang, B. Zheng, S. Huang, Org. Lett., 2023, 25, 293-297.

DOI: 10.1021/acs.orglett.2c04204

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An electrolysis of terminal alkynes into their corresponding carboxylic acids in an undivided cell at room temperature avoids transition metal catalysis and stoichiometric chemical oxidants. The reaction tolerates a variety of aryl, heteroaryl, and alkyl alkynes. Sodium nitrite serves a triple role as the electrolyte, nitryl radical precursor, and a nitrosating reagent.

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proposed mechanism

General procedure

A three necked round bottom flask was equipped with a stir bar, two platinum electrodes (10 mm×10 mm×0.2 mm) as both the anode and cathode. Then terminal alkyne (0.6 mmol), AcOH (345.5 μL, 6 mmol, 10 equiv), sodium nitrite (41.8 mg, 0.72 mmol, 1.2 equiv), MeCN (10 mL) and water (2 mL) were combined and added. The reaction mixture was stirred and electrolyzed at a constant current of 5 mA (I = 5 mA/cm2) under room temperature. The reaction was monitored by TLC. The solvent was removed with a rotary evaporator when the reaction was finished. The residue was purified by column chromatography to afford the desired product (PE/EA = 4/1).

Key Words

cleavage of alkynes, Nef reaction, sodium nitrite, electrochemistry

ID: J54-Y2023