Impact of Host Flexibility on Selectivity in a Supramolecular Host-Catalyzed Enantioselective aza-Darzens Reaction

A highly enantioselective aza-Darzens reaction (up to 99% ee) catalyzed by an enantiopure supramolecular host has been discovered. To understand the role of host structure on reaction outcome, nine new gallium­(III)-based enantiopure supramolecular assemblies were prepared via substitution of the ex...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2022-06, Vol.144 (25), p.11425-11433
Main Authors: Bierschenk, Stephen M., Pan, Judy Y., Settineri, Nicholas S., Warzok, Ulrike, Bergman, Robert G., Raymond, Kenneth N., Toste, F. Dean
Format: Article
Language:English
Subjects:
amides
catalysts
cavities
condensation
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
selectivity
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Summary:A highly enantioselective aza-Darzens reaction (up to 99% ee) catalyzed by an enantiopure supramolecular host has been discovered. To understand the role of host structure on reaction outcome, nine new gallium­(III)-based enantiopure supramolecular assemblies were prepared via substitution of the external chiral amide. Despite the distal nature of the substitution in these catalysts, changes in enantioselectivity (61 to 90% ee) in the aziridine product were observed. The enantioselectivities were correlated to the flexibility of the supramolecular host scaffold as measured by the kinetics of exchange of a model cationic guest. This correlation led to the development of a best-in-class catalyst by substituting the gallium­(III)-based host with one based on indium­(III), which generated the most flexible and selective catalyst.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.2c04182