The Mechanism Studies On C-C And C-P Bond Formation Through Decarbonylative Coupling Reaction

Decarbonylation coupling catalyzed by Transition metal is a commonly used method for constructing new chemical bonds.This type of reaction is usually accomplished by four steps: oxidative addition,metal transfer,decarbonylation,and reduction elimination.It is found that such reactions can be used to construct C-C bonds and C-P bonds recently and those reactions have been applied in organic synthesis.However,there are still many problems of these reactions,such as the use of transitional precious metals and poor universality of substrates.In addition,the detailed mechanism of the reaction is still unclear,which seriously hinders people’s understanding and subsequent improvement of these reactions.Therefore,this paper uses density functional theory(DFT)to systematically study the mechanism of nickel-catalyzed decarbonylation of benzophenone to construct C-C bond and the mechanism of cross-coupling of palladium-catalyzed amide to construct C-P bond,which explains the relevant reaction reasonably.This paper mainly includes the following two parts:1.Mechanism calculation of carbon-carbon bond formation by nickel-catalyzed decarbonylation of simple benzophenone: The experimenter reported the decarbonylation of simple ketone molecules catalyzed by nickel to construct carbon-carbon bonds.The related reactions have important applications in the fields of organic material synthesis and natural product synthesis.The experimenter proposed the reaction mechanism briefly and predict the oxidation addition is the the rate-determining step based on the previous research.We selected benzophenone as the reaction substrate and studied the mechanism of the reaction systematically.The calculation results show that the whole reaction has undergone four steps of oxidation addition,migration extrusion,decarbonylation and reduction elimination,in which oxidation addition is easy to occur,and reduction elimination is the key step of reaction.This result modifies the mechanism put forward by the experimenter "oxidative addition is the rate-determining step,and reduction elimination is easy to occur." What’s more,our calculation results on the effect of the electronic effects of different substituents are also consistent with the experimental results,that is,the substrate with the electron-withdrawing group CF3 has the fastest rate.In general,our theoretical calculation results not only propose a feasible reaction mechanism,but also explain the experimental phenomenon reasonably.2.Computational mechanism for palladium-catalyzed C-P bond construction through decarbonylative phosphorylation of Amide: The experimenter reported the work of palladium-catalyzed cross-coupling of amide decarbonylation phosphorylation to construct C-P bonds,and the related reactions were applied in the fields of medicinal chemistry and agrochemistry.We studied the mechanism of the reaction and selected 1-benzoylpiperidine-2,6-dione as the reaction substrate.The calculation results show that the whole reaction has undergone oxidative addition,ligand exchange,hydrogen transfer,decarbonylation and reduction elimination;wherein decarbonylation is the rate-determining step of the reaction.We propose that the ion pair effects,hydrogen bonding effects,and flexibility of the ligand 1,4-bis(diphenylphosphine)butane(DPPB)promote the reaction.The mechanism proposed by us reasonably explains the experiment and shows good consistency between theoretical and experimental.