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Stereoselective Synthesis of Atropisomeric Acridinium Salts by the Catalyst-Controlled Cyclization of ortho-Quinone Methide Iminiums

Wu, Xingxing and Sparr, Christof. (2022) Stereoselective Synthesis of Atropisomeric Acridinium Salts by the Catalyst-Controlled Cyclization of ortho-Quinone Methide Iminiums. Angewandte Chemie International Edition, 61 (19). e202201424.

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Abstract

Quinone methides are fundamental intermediates for a wide range of reactions in which catalyst stereocontrol is often achieved by hydrogen bonding. Herein, we describe the feasibility of an intramolecular Friedel-Crafts 6π electrocyclization through ortho-quinone methide iminiums stereocontrolled by a contact ion pair. A disulfonimide catalyst activates racemic trichloroacetimidate substrates and imparts stereocontrol in the cyclization step, providing a new avenue for selective ortho-quinone methide iminium functionalization. A highly stereospecific oxidation readily transforms the enantioenriched acridanes into rotationally restricted acridiniums. Upon ion exchange, the method selectively affords atropisomeric acridinium tetrafluoroborate salts in high yields and an enantioenrichment of up to 93 : 7 e.r. We envision that ion-pairing catalysis over ortho-quinone methide iminiums enables the selective synthesis of a diversity of heterocycles and aniline derivatives with distinct stereogenic units.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Organische Chemie (Sparr)
UniBasel Contributors:Wu, Xingxing and Sparr, Christof
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Wiley
ISSN:1433-7851
e-ISSN:1521-3773
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
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Last Modified:15 Dec 2022 10:16
Deposited On:15 Sep 2022 14:28

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