|Important Progress in the Study of Palladium-Catalyzed Asymmetric Cycloaddition Was Made by Prof. GUO Hongchao's Research Group
Recently, important progress in the research of palladium-catalyzed asymmetric cycloaddition reaction was made by the research group of GUO Hongchao, professor of CAU College of Science. For the first time, a palladium-catalyzed asymmetric [4+2] cycloaddition reaction of 2-methenyltrimethylene carbonate with active olefins was achieved. This achievement provides a concise and efficient synthetic method for the construction of organisms with potential biological activity such as Chiral spiropyrazolone-tetrahydropyran derivatives, spirocyclic indanone-tetrahydropyran derivatives. The corresponding research results were published online in German Applied Chemistry (Angewandte Chemie International Edition, DOI: 10.1002/anie.202002765).
In recent years, π-allyl palladium zwitterionic intermediates have been playing an important role in the rapid and efficient construction of various heterocyclic compounds. In the related researches on various zwitterions formed by palladium catalysis, there are few related reactions based on 2-methenyltrimethylene carbonate, thus the related asymmetric cycloaddition reaction has never been realized. The research team of Prof. GUO successfully realized the first palladium-catalyzed asymmetric [4+2] cycloaddition reaction involving 2-methenyltrimethylene carbonate based on reaction mechanism analysis, rational design and fine screening. In this reaction, commercially available metal palladium catalyst and chiral phosphine are used as ligands, 2-methenyltrimethylene carbonate and inexpensive and readily available unsaturated pyrazolone, indone derived olefin or barbiturate activated olefin are used as the reaction substrate. The reaction was made under mild conditions by using simple operation, and a series of novel chiral spiro compounds can be obtained with high yield, high enantioselectivity and high diastereoselectivity.
This method not only possesses good compatibility with the substitution of the substrate, but also provides a good broad spectrum for the type of substrate. In addition, the chiral spiro products produced by the reaction can be derivatized to obtain various types of other chiral products while keeping the chirality, which provides a favorable basis for the practical application of the subsequent reaction.
Being oriented towards developing new pesticides, Prof. GUO 's research group has been devoting to the research of cycloaddition and cyclization reactions catalyzed by metal and organic small molecule catalysts. At present, a number of new and efficient cycloaddition reactions have been developed. This work is another important result in the field of cycloaddition reaction achieved by this group. The first author of this latest work is PhD student MAO Biming from College of Science. Main collaborators are undergraduate YAN Zhengyang and PhD student LIU Honglei. The research was financially aided by the National Natural Science Foundation of China, Ministry of Science and Technology, and University Fundamental Research Fund.