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A Structurally Robust Chiral Borate Ion: Molecular Design, Synthesis, and Asymmetric Catalysis
Author(s) -
Uraguchi Daisuke,
Ueoka Fumito,
Tanaka Naoya,
Kizu Tomohito,
Takahashi Wakana,
Ooi Takashi
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202001637
Subject(s) - boron , oxonium ion , catalysis , nucleophile , enantioselective synthesis , combinatorial chemistry , selectivity , chemistry , ion , organocatalysis , computational chemistry , organic chemistry
Catalysis by chiral weakly‐coordinating anions (WCAs) remains underdeveloped due to the lack of a molecular design strategy for exploiting their characteristics, such as the non‐nucleophilic nature. Here, we report the development of a chiral borate ion comprising an O,N,N,O‐tetradentate backbone, which ensures hitherto unattainable structural robustness. Upon pairing with a proton, the hydrogen borate acts as an effective catalyst for the asymmetric Prins‐type cyclization of vinyl ethers, providing access to structurally and stereochemically defined dihydropyrans. The key to selectivity control is the distinct ability of the borate ion to discriminate the prochiral faces of the acyclic oxonium ion intermediate and dictate the regiochemical outcome. We anticipate that this study paves the way for exploring the untapped potential of WCA catalysis for selective chemical synthesis.