Theoretically Study On The Mechanism Of Thiol-Ene Click Reaction

In the early years of this decade, Sharpless and co-workers brought to light the archetypal concept of click chemistry. Ever since, an exponentially increasing number of papers have appeared on the use of the click reaction. The great success of this process as a ligation tool in fields of research as diverse as organic synthesis, polymer and material science, medicinal chemistry, molecular biology, and biotechnology relies on the efficiency and selectivity, the ready occurrence of the process under aerobic conditions, and its wide scope regardless of the molecular complexity of the reagents. It is necessary to investigate the thiol-ene click reaction system theoretically and directing the synthesis methods and practical applications. In this thesis, quantum methods have been applied to study the thiol-ene click reaction mechanisms. The main contents are summarized as follows:(1) The mechanism of thiol-ene radical mechanism was investigated firstly. The geometries and harmonic frequencies of reactants, intermediates, transition states and products were calculated at the B3LYP/6-311++G** and MP2/6-311++G** level, and the potential energy profile is further refined by single-point energy calculations at the G3MP2B3 levels. To get more precise reaction informations, the rate constants of all reactions were evaluated by transition state theory (TST). The present calculations show the different radical mechanisms occurred in different thiol-ene systems.(2) The mechanism of trialkyl phosphine-catalyzed thiol-ene Michael addition was investigated by using B3LYP, MP2 and G3MP2B3 methods as well as the conductor-like polarized continuum model. The geometries, charges, energies, and free energy reaction profiles of the reaction in solution phase were explored. The present calculations demonstrate that the mechanism proposed in the present work is in reasonable agreement with the reported experimental results.