Theoretical Study On The Activation Mechanism Of Rhodium-catalyzed Carbon-containing Nucleophiles

The continuous progress of synthetic chemistry meets the increasing material needs of human beings,and the most critical process in synthetic chemistry is the construction of covalent bonds.In recent decades,with the rapid development of organic reactions catalyzed by transition metals,the continuous improvement and breakthrough of complex reactions and the synthesis and modification of complex molecules are the driving forces for the continuous progress of synthetic chemists.Among them,the reaction of carbon-containing nucleophiles activated by transition metal rhodium to construct covalent bonds has become a topic reported by synthetic chemists.As rhodium catalyzed new reactions appear one after another,the activation modes of rhodium catalysts for substrates are also endless.Therefore,the research work on the mechanism of rhodium catalysis is also urgently needed.The theoretical calculation can help us to deeply understand the mechanism and selectivity of the reaction.Meanwhile,it can help us understand the nature of the reaction.On this basis,it enables us to carry out the purposeful design of the reaction,so as to realize the conversion with high selectivity and high reactivity.In this paper,we use theoretical calculations to study the activation of carbon-containing nucleophiles catalyzed by rhodium.The main research results are as follows:1.We have used theoretical calculations to thoroughly study the mechanism and selectivity of monovalent rhodium-catalyzed silane-activated alkyne insertion reactions.Our proposed mechanism includes the three elemental reactions of carbon-silicon bond oxidative addition to metal rhodium,alkyne insertion and reduction of carbon-silicon bond.We give a reasonable explanation for the cause of the enantioselectivity under rhodium catalysis using the three-layer chiral transfer model: the chiral binaphthylphosphite ligand in the back layer controls the relative position of each group,the middle metal layer transfers the chiral environment to the silane substrate added on the front,and the 2D profile analysis further confirms the model.2.A theoretical study on the rhodium-catalyzed [4 + 1] cycloaddition reaction of solvent controlled chemoselectivity using density functional calculation method.The calculation results show that the reaction will undergo elementary reactions such as nitrogen-hydrogen bond cleavage / carbon-hydrogen bond cleavage / alkynes insertion /?-F elimination / metathesis / diene insertion / protonation.The reason for the chemical selectivity is due to the energy crossover of the metathesis process under different solvents.The NCI analysis explained that the enantioselectivity is caused by the ?-?stacking effect between the substrate and the ligand.3.The mechanism of [4 + 1] cycloaddition reaction by rhodium-catalyzed carbon-hydrogen bond activation and carbene insertion was studied in depth using density functional method M06.The calculation results show that the reaction first undergoes nitrogen-hydrogen bond activation / carbon-hydrogen bond activation,and then performs elementary reactions such as nitrogen-oxygen bond oxidation / Lossen rearrangement / carbene insertion / nucleophilic attack / protonation.At the same time,we also prove that the path of carbene insertion first and then Lossen rearrangement is a relatively unfavorable process.