Theoretical Study On The Reaction Mechanism Of Rhodium/gold Catalyzed CH Alkynylation And Cyclization Of N-methylisoquinolinone Or Allene Compounds

In recent years,environmental pollution has become more and more obvious,and the problem of depletion of the earth's resources has become serious.The development of more green and efficient new catalysts has become a focus area for most of chemists.Raising the chemical reaction to a new height,realizing the greening and cleanliness of chemical production,solving the current severe environmental problems,and achieving sustainable development are still the direction of the unremitting efforts of researchers in the chemical and related disciplines.Therefore,in order to improve and develop new catalytic reactions,it is necessary to further understand the relevant catalytic reaction mechanism.Therefore,in this paper we mainly use quantum chemical calculation methods to study the geometry of the reactants,intermediates and transition states,and to calculation the energy barrier of the reaction,and then to understand the reaction mechanism and design a new related reaction.This paper mainly contains two contents:?1?In the supported of density functional theory?DFT?,we investigated the regioselectivity of C/C-4 alkynylation of N-methylisoquinolinone catalyzed by Rh/Au.In this study we explored the multifunctional role of the substrate 1-[?triisopropylsilyl?ethynyl]-1,2-benzoiodo-3?1H?-one?TIPS-EBX?.In the catalytic reaction using[Cp*RhCl₂]₂,TIPS-EBX acts as a Brons base and undergoes a self-assisted deprotonation mechanism to produce a C8-alkynylation product.This apparent regioselectivity is attributed to the electronic effect.In contrast,due to the steric effect,the C4-alkynylation product became the main product again when AuCl was used as the catalyst.This is mainly because the iodine?III?center in the TIPS-EBX moiety can be used as a strong Lewis acid to effectively activate the alkyne moiety in this reaction.?2?By using density functional theory?DFT?calculations,we investigated the reaction mechanism of gold-catalyzed[2+3]and[2+2]cycloisomerization reactions.The stepwise addition of an olefin to the gold-allyl species followed by the selectivity-determining cyclization is calculated to be the most favorable mechanism,although this mechanism is considered to be infeasible that in the experiment.We verified the experimental results by using the electron-donating group and the electron-withdrawing group instead of the reaction substrate.The calculated data is consistent with the Hammett analysis that the experiment has proposed.The regioselectivity of the reaction was elucidated by our calculations.