In recent years, electrocatalysis has swiftly established its dominance in organic synthesis owing to its high efficiency and low contamination. However, without developed methods for controlling regio- and stereochemistry, the selectivity control proved difficult in this field.
Recently, the research team led by Prof. GUO Chang from the University of Science and Technology of China (USTC) succeeded in realizing the asymmetric electrochemical radical functionalization of alkenes and allylation. The relevant achievements were reported in Science Advances and Angew. Chem. Int. Ed.
The team first activated the nucleophile with stereoselective Lewis acid-Nickle complex to form a key radical intermediate through oxidation on the anode.
The formation of the key radical intermediate. (Image by Prof. GUO Chang’s team)
The intermediate was then added to various alkenes to form new radicals that ultimately turned into alkene difunctionalization (Path1) or alkenylation (Path2) products through further oxidation and addition (or elimination). The products analysis showed high asymmetric selectivity thanks to the single electron-transfer (SET) process and the Nickel catalyst.
The researchers carried out extensive experiments on the function and necessity of each reaction component in order to better understand the mechanism of the asymmetric electrolytic reaction. They discovered that the electrode potentials of the nickel-mediated alkene oxidation are significantly lower than those of the direct oxidation.
The suggested mechanism of the reaction. (Image by Prof. GUO Chang’s team)
Moreover, using similar methods, the team developed an electrocatalytic asymmetric allylation in which the intermediate was an electron-deficient α-ketone radical.
“We believe that in the near future, the realization of enantioselective electrochemical transformations will improve the scope of electrosynthesis and pave the way for exploring new chemical spaces and developing solutions to challenging synthetic problems,” says the paper.
Given the essential role of synthesis in many areas, the research is undoubtfully a profound insight into the potential of electrosynthesis.
(Written by LI Jialin, edited by ZHANG Wenjing, USTC News Center)