Theoretical Study On The Mechanism Of Gold-catalyzed Aminoalkynes Reaction

Transition metal catalysis is an important research method for carbon-carbon bond construction in organic synthesis reactions.As a result of intrinsic p-activation property of gold catalysts,gold-catalyzed annulations of alkynes with weak nucleophiles are powerful tools to access highly functionalized carbo-and Heterocycles.In this paper,the M06 level of density functional theory(DFT)was used to perform the theoretical calculations of the following two subjects,and a reasonable reaction mechanism was proposed for the corresponding experimental research to explain the experimental phenomena and experimental results.It is anticipated that the calculated results would provide theoretical guidance for developing new reactions and designing novel transition metal catalysts.The findings found in this work are as follows:⑴ The reaction mechanism of gold(I)-catalyzed cascade reaction of aminaloalkynes involving Petasis-Ferrier arrangement was studied with the aid of density functional theory calculations.Our study showed that two mechanisms proposed by the Patil group and by us are possible.With the substrate bearing a-C≡C-H component the mechanism by us is preferred in which the reaction undergoes first a Petasis-Ferrier rearrangement.With the substrate bearing a-C≡C-Ar component the mechanism by the Patil group is preferred in which the reaction undergoes first a protodeauration step.Both pathways are possible and can be active,and which one will prevail will depend on the reaction substrate,or rather on the size of the group attached to the alkynyl carbon atom.⑵ The mechanism of gold(I)/gold(III)catalytic oxidation of 1,2-aminooxygenation was studied theoretically by means of density functional theory calculations.Our research proposes two possible reaction pathways from the cis-and trans-coordination of the substrate to gold catalysts.It is believed that the initial oxidation of the gold catalyst with the fluorine reagent provides an active cationic gold(III)species that nucleophilically attacks at the alkyne moiety of the substrate to provide a trans amination intermediate.The isobutylene dissociated from a vinyl gold(III)intermediate,followed by intramolecular SN2-type nucleophilic substitution and regeneration of the catalyst give the product.Based on the theoretical calculations,the reaction path associated with the nucleophilic attack to obtain the trans-rather than the cis-amination intermediate was found to be more favorable.