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Backbone-Modified C₂-Symmetrical Chiral Bisphosphine TMS-QuinoxP* : Asymmetric Borylation of Racemic Allyl Electrophiles

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Title: Backbone-Modified C₂-Symmetrical Chiral Bisphosphine TMS-QuinoxP* : Asymmetric Borylation of Racemic Allyl Electrophiles
Authors: Iwamoto, Hiroaki Browse this author
Ozawa, Yu Browse this author
Takenouchi, Yuta Browse this author
Imamoto, Tsuneo Browse this author
Ito, Hajime Browse this author →KAKEN DB
Keywords: Chiral bisphosphine ligand
Direct enantioconvergent reaction
Asymmetric borylation
DFT calculation
Issue Date: 5-May-2021
Publisher: American Chemical Society(ACS)
Journal Title: Journal of the American Chemical Society
Volume: 143
Issue: 17
Start Page: 6413
End Page: 6422
Publisher DOI: 10.1021/jacs.0c08899
Abstract: A new C₂-symmetrical P-chirogenic bisphosphine ligand with silyl substituents on the ligand backbone, (R,R)-5,8-TMS-QuinoxP*, has been developed. This ligand showed higher reactivity and enantioselectivity for the direct enantioconvergent borylation of cyclic allyl electrophiles than its parent ligand, (R,R)-QuinoxP* (e.g., for a piperidine-type substrate: 95% ee vs 76% ee). The borylative kinetic resolution of linear allyl electrophiles was also achieved using (R,R)-5,8-TMS-QuinoxP* (up to 90% ee, s = 46.4). An investigation into the role of the silyl groups on the ligand backbone using X-ray crystallography and computational studies displayed interlocking structures between the phosphine and silyl moieties of (R,R)-5,8-TMS-QuinoxP*. The results of DFT calculations revealed that the entropy effect thermodynamically destabilizes the dormant dimer species in the catalytic cycle to improve the reactivity. Furthermore, in the direct enantioconvergent case, detailed calculations indicated a pronounced enantioselective recognition of carbon–carbon double bonds, which is virtually unaffected by the chirality at the allylic position, as a key for the borylation from both enantiomers of racemic allyl electrophiles.
Rights: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see
Type: article (author version)
Appears in Collections:総合化学院 (Graduate School of Chemical Sciences and Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 小澤 友

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