Studies On The Reductive Elimination Of Transition Metal -Catalyzed Cross-Coupling Reactions

In most of the transition metal catalyzed cross-coupling reactions, reductive elimination is the key step which build the C-C or C-X bond directly, is the step which involves in product generation directly, which controls the possibility and selectivity of reaction to a certain extent. In the early work, chemists wre interested in building sp2C-sp2C bond, in these reactions, reductive elimination is not involved in rate-limiting step, which makes it rarely been concerned. With the research interests was shifted to C-X bond formed, the reductive elimination had gradually received extensive attention. In this paper, theoretical and experimental studies were carried out on this step, and our work is consists of the following two parts:Part 1, Mechanistic study on ligand controlled Rregioselectivity-switchable Hydroarylation reaction by DFT. Yoshikai’s group reported an interesting Co-catalyzed hydroarylation of styrene in 2010, we studied the process by DFT, and find the regioselectivity of this reaction depends on repulsive force between the substrates and ligand (teric hindrance and electrostatic repulsion). Further studies showed that the repulsive force between the ligand and the substrate depends not only on the volume and electronic effect of the ligand, the different skeletal structure orientation ligand also plays a vital role.Part 2, we first realized the formation of C-OTf Aryl bond by transition metal catalyzed, based on a new method which can promote reductive elimination and is developed by ourselves. Preliminary DFT studies were performed to provide insight into the selectivity of C-OTf and C-F reductive elimination. Benzophenone was used as ligand to accelerate the palladium-catalyzed reaction by the first time.In summary, this paper mainly fcous on the reductive elimination of transition metal catalyzed coupling reactions. More importantly, a method is proposed to promote reductive elimination, and for the first time using this method to achieve the first C-OTf bond formed by reductive elimination. I believe the results of these two studies, will help chemists to understand reductive elimination and to achieve a wider variety of C-X bonds which never been achieved by reductive elimination.