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Metal-catalyzed alkane/aromatic carbon-hydrogen bond selective functionalization is an ideal, highly efficient method of chemical conversion. The reduction-elimination reaction is one of the key reactions in the construction of new CC/CX (heteroatom) bonds in the functionalization of carbon and hydrogen bonds. However, reduction and elimination reactions such as CO/C–N/C–F and other bond formation reactions are often difficult. One strategy is to use ligands to accelerate the reduction to eliminate the reaction, whereas ligands often interfere with the carbon-carbon functionalization reaction; another strategy is to use external oxidants to oxidize metal species to higher valence states, thereby facilitating oxidation elimination reactions. However, chemical oxidants are generally more expensive, toxic, and can create byproducts that interfere with the reaction. Therefore, finding an oxidant that can overcome the above drawbacks is an important research topic in the field of carbon-hydrogen bond functionalization.
The Mei Tiansheng research team of the State Key Laboratory of Organometallic Chemistry of the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, has successfully implemented metal-catalyzed selective functionalization of carbon-hydrogen bonds using a new strategy of electrochemical oxidation instead of traditional chemical oxidants (J. Am. Chem. Soc. 2017, ASAP, DOI: 10.1021/jacs.7b01232). The catalytic system uses clean, green, and inexpensive currents to oxidize metal species and promote the reduction and elimination of C–O bonds. At the same time, different nucleophiles can be added to the reaction to obtain the corresponding products, and a series of C–O bonding reactions can be achieved. Compared with the traditional chemical oxidation system, this system has the following advantages: 1) The electrochemical oxidation system avoids the use of toxic and expensive chemical oxidants such as PhI(OAc)2, making the carbon-hydrogen bond functionalization more Economic, green; 2) Due to the controllability of the current intensity and voltage, the new system developed in this study gives a better chemical selectivity; 3) The use of cyclic voltammetry (CV) unique to electrochemistry, It can effectively track the valence changes of metal species, so it provides a good platform for in-depth study of the reaction mechanism.
Utilizing the advantages of organic electrochemistry to solve the problems in the traditional metal organic chemistry is the focus of future work of Mei Tiansheng's research team.
The above research was funded by the China Youth Ministry’s 1000-member youth plan, the National Natural Science Foundation of China, the Shanghai Science and Technology Commission, the Chinese Academy of Sciences, the Shanghai Institute of Organic Chemistry of the Chinese Academy of Sciences and the State Key Laboratory of Organometallic Chemistry.
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