A theoretical study on synthesis mechanisms of α,β-unsaturated carbon γ-amino ester catalyzed by PPh3
In this paper, generation mechanism of α,β-unsaturated carbon γ-amino esters catalyzed by triphenylphosphine (PPh3) have been investigated using density functional theory (DFT). Two possible mechanisms (Mechanism A and Mechanism B) are proposed, in which there are three possible reaction pathways (Path A1/A2/A3 in Mechanism A and Path B1/B2/B3 in Mechanism B) except for the generation of the intermediate M1. The calculated results demonstrate that the energy favorable pathways (Path A2 and Path B2) include three process: the first step is an intermolecular proton transfer accompanied by a nucleophilic attack, the second step is an intramolecular proton transfer process, and the last step is the dissociation of PPh3 and the product generation. Furthermore, the reaction pathway associated with the E-isomer is the most favorable pathway and leads to the main product (E-P), which is in good agreement with the experimental results. This work might be helpful for understanding the significant roles of catalyst PPh3 and thus provide valuable insights on the rational design of potential catalysts for this kind of reactions.
KeywordsReaction mechanism Triphenylphosphine Amino ester DFT
The authors acknowledge financial support from the National Natural Science Foundation of China (Nos. 21001095 and J120062), University Key Research Programs of Department of Education in Henan Province (Grant Nos. 15A150082 and 14A150033), and Training Foundation of Zhengzhou University Innovation & Enterprise Capability of College Student (No. 2016xjxm264).
Compliance with ethical standards
Ethical statement/conflict of interest
The authors declare that they have no conflict of interest. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.
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