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Anion-π catalysis: Bicyclic products with four contiguous stereogenic centers from otherwise elusive diastereospecific domino reactions on π-acidic surfaces

Liu, Le and Cotelle, Yoann and Klehr, Juliane and Sakai, Naomi and Ward, Thomas R. and Matile, Stefan. (2017) Anion-π catalysis: Bicyclic products with four contiguous stereogenic centers from otherwise elusive diastereospecific domino reactions on π-acidic surfaces. Chemical Science, 8 (5). pp. 3770-3774.

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Abstract

Anion–π interactions have been introduced recently to catalysis. The idea of stabilizing anionic intermediates and transition states on π-acidic surfaces is a new fundamental concept. By now, examples exist for asymmetric enolate, enamine, iminium and transamination chemistry, and the first anion–π enzyme has been created. Delocalized over large aromatic planes, anion–π interactions appear particularly attractive to stabilize extensive long-distance charge displacements during domino processes. Moving on from the formation of cyclohexane rings with five stereogenic centers in one step on a π-acidic surface, we here focus on asymmetric anion–π catalysis of domino reactions that afford bicyclic products with quaternary stereogenic centers. Catalyst screening includes a newly synthesized, better performing anion–π version of classical organocatalysts from cinchona alkaloids, and anion–π enzymes. We find stereoselectivities that are clearly better than the best ones reported with conventional catalysts, culminating in unprecedented diastereospecificity. Moreover, we describe achiral salts as supramolecular chirality enhancers and report the first artificial enzyme that operates in neutral water with anion–π interactions, i.e., interactions that are essentially new to enzymes. Evidence in support of contributions of anion–π interactions to asymmetric catalysis include increasing diastereo- and enantioselectivity with increasing rates, i.e., asymmetric transition-state stabilization in the presence of π-acidic surfaces and inhibition with the anion selectivity sequence NO3− > Br− > BF4− > PF6−.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Bioanorganische Chemie (Ward)
UniBasel Contributors:Ward, Thomas R. R. and Cotelle, Yoann and Klehr, Juliane
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Royal Society of Chemistry
ISSN:2041-6520
e-ISSN:2041-6539
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:22 Jan 2018 10:10
Deposited On:22 Jan 2018 10:09

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