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Title: Ion pair catalyst - pentanidinium
Authors: Qin, Yimin
Zhang, Zhenqiang
Ye, Xinyi
Tan, Choon-Hong
Keywords: Science::Chemistry
Issue Date: 2023
Source: Qin, Y., Zhang, Z., Ye, X. & Tan, C. (2023). Ion pair catalyst - pentanidinium. The Chemical Record, e202200304-.
Journal: The Chemical Record
Abstract: In this account, we further describe our already developed N-sp2 hybrid guanidinium as an efficient phase-transfer catalyst and ion pair catalysis based on N-sp2 hybrid pentanidinium and its application in some new reactions. The sp3 hybrid quaternary ammonium salt has a tetrahedral structure, which means that three sides of it can be effectively steric, allowing the remaining side to be close to the substrate. However, the sp2 hybrid ammonium salt allows the substrate to form ion pairs from both directions respectively, so it is a greater challenge to control the stereoselectivity of the reaction. Van der Waals forces, such as hydrogen bonds and π-π${\pi -\pi }$ interactions, have been used to make electrophiles approach from a certain direction, leading to a higher enantioselectivity. Based on the above idea, we designed an N-sp2 hybrid phase-transfer catalyst, pentanidinium. Pentanidinium has five conjugated nitrogen atoms, one of which has a formal positive charge, which is necessary for it to become an ion pair catalyst. We have confirmed that pentanidinium can catalyze α-hydroxylation of 3-substituted-2-oxindoles, Michael addition of 3-alkyloxindoles with vinyl sulfone, and alkylation reactions of sulfenate anions and dihydrocoumarins, desymmetrization of pro-chiral sulfinate to afford enantioenriched sulfinate esters. Pentanidinium with side chain structure changes can also be catalyzed efficiently with enantioconvergent halogenophilic nucleophilic substitution, including azidation and thioesterification. In the reaction catalyzed by pentanidinium, it always attracts us with the advantages of low catalytic load and good enantioselectivity.
ISSN: 1527-8999
DOI: 10.1002/tcr.202200304
Schools: School of Chemistry, Chemical Engineering and Biotechnology 
Rights: © 2023 The Chemical Society of Japan and Wiley-VCH GmbH. All rights reserved.
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:CCEB Journal Articles

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