Chinese scientists have made important progress in the field of boron radical-catalyzed asymmetric synthesisThe reporter learned from the University of Science and Technology of China that the joint research team of Professor Wang Yifeng, Professor Fu Yao and Associate Professor Zhang Fenglian of the Key Laboratory of Precision and Intelligent Chemistry of the university has developed a class of asymmetric cyclic isomerization reactions catalyzed by chiral boron radicals. On December 1, the research results were published in the international authoritative academic journal Science.
Schematic diagram of chiral boron radical catalyst. Courtesy of University of Science and Technology of China Asymmetric catalysis is an important way to synthesize chiral functional molecules and understand the chiral world. The development of chiral catalysts with novel structures and functions and the asymmetric reactions they catalyze are the focus of research in the field of asymmetric catalysis. Free radical species contain unpaired electrons, which are highly reactive and have different reaction modes from ionic reactions, and play an increasingly important role in organic synthetic chemistry. The asymmetric reaction using free radicals as chiral catalysts is different from transition metal catalysis, organic small molecule catalysis and enzyme catalysis in terms of reaction mechanism, catalytic mode and functional group compatibility, and is expected to provide new ideas and strategies for the synthesis of chiral molecules. However, it is extremely challenging to achieve this type of asymmetric catalysis: first, organic radicals are extremely reactive and easily inactivated in reactions, making it extremely difficult to construct an effective catalytic cycleSecond, the structure of most free radicals is not easy to modify and modify, and it is difficult to finely regulate the chiral environment. Focusing on the above challenges, based on the previous in-depth research on the performance of organic boron radicals, the research team designed a class of chiral azacarbene-boron radical catalysts with novel structures and easy modifications, and developed a new class of reaction mechanisms and catalytic cycles based on their principle of reversibility of addition to unsaturated hydrocarbons. It is understood that this kind of chiral boron radical precursors are simple to prepare, rich in structure and easy to modify, which provides a basis for the chiral regulation of reactions. In addition, the research team also used quantum chemical calculations, electron paramagnetic resonance spectroscopy, deuterium labeling experiments and other methods to explain the catalytic reaction mechanism and stereoselectivity**, realize the precise control of the catalytic process, and lay a theoretical foundation for the future precise design of catalysts based on artificial intelligence. According to the researchers, this work not only demonstrates the powerful function of boron radical catalytic asymmetric synthesis for the first time, but also inspires and promotes the development of other host group radical catalysts and their asymmetric catalytic reactions, providing new design ideas and catalytic modes for the synthesis of chiral functional molecules. **Xinhua News Agency