Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

On- and Off-Cycle Catalyst Cooperativity in Anion-Binding Catalysis.

ABSTRACT: Chiral, neutral H-bond donors have found widespread use as catalysts in enantioselective reactions involving ion-pair intermediates. Herein, a systematic mechanistic study of a prototypical anion-binding reaction, the thiourea-catalyzed enantioselective alkylation of ?-chloroethers, is detailed. This study reveals that the catalyst resting state is an inactive dimeric aggregate that must dissociate and then reassemble to form a 2:1 catalyst-substrate complex in the rate-determining transition structure. Insight into this mode of catalyst cooperativity sheds light on the practical limitations that have plagued many of the H-bond donor-catalyzed reactions developed to date and suggests design strategies for new, highly efficient catalyst structures.

SUBMITTER: Ford DD

PROVIDER: S-EPMC5108296 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

On- and Off-Cycle Catalyst Cooperativity in Anion-Binding Catalysis.

Ford David D DD Lehnherr Dan D Kennedy C Rose CR Jacobsen Eric N EN

Journal of the American Chemical Society 20160615 25

Chiral, neutral H-bond donors have found widespread use as catalysts in enantioselective reactions involving ion-pair intermediates. Herein, a systematic mechanistic study of a prototypical anion-binding reaction, the thiourea-catalyzed enantioselective alkylation of α-chloroethers, is detailed. This study reveals that the catalyst resting state is an inactive dimeric aggregate that must dissociate and then reassemble to form a 2:1 catalyst-substrate complex in the rate-determining transition st ...[more]

PMID: 27276389

Similar Datasets

Silanediol Anion Binding and Enantioselective Catalysis.

Project description:Silanediols possess unique and complementary catalytic activity in reactions that are likely to proceed through anion binding. This article directly compares silanediols, thioureas, and squaramides in three separate anion-binding processes. The catalytic abilities of select members of each family are directly correlated to association constant.

| S-EPMC6548508 | biostudies-literature

Stereodivergent Anion Binding Catalysis with Molecular Motors.

Project description:A photoresponsive chiral catalyst based on an oligotriazole-functionalized unidirectional molecular motor has been developed for stereodivergent anion binding catalysis. The motor function controls the helical chirality of supramolecular assemblies with chloride anions, which by means of chirality transfer enables the enantioselective addition of a silyl ketene acetal nucleophile to oxocarbenium cations. Reversal of stereoselectivity (up to 142?% ?ee) was achieved through rotation of the motor core induced by photochemical and thermal isomerization steps.

| S-EPMC7004205 | biostudies-literature

Enantioselective vinylogous-Mukaiyama-type dearomatisation by anion-binding catalysis.

Project description:The first enantioselective vinylogous Mukaiyama-type dearomatisation of heteroarenes under anion-binding catalysis is presented. A recyclable tetrakistriazole catalyst was used for the enantiocontrol of the remote vinylogous active position of silyl dienol ethers. This approach provided chiral heterocycles bearing α,β-unsaturated chains with complete regioselectivity and excellent enantioselectivities (up to 97.5 : 2.5 e.r.).

| S-EPMC8438702 | biostudies-literature

Enantioselective transition-metal catalysis via an anion-binding approach.

Project description:Asymmetric transition-metal catalysis represents a powerful strategy for accessing enantiomerically enriched molecules1-3. The classical strategy for inducing enantioselectivity with transition-metal catalysts relies on direct complexation of chiral ligands to produce a sterically constrained reactive metal site that allows formation of the major product enantiomer while effectively inhibiting the pathway to the minor enantiomer through steric repulsion4. The chiral-ligand strategy has proven applicable to a wide variety of highly enantioselective transition-metal-catalysed reactions, but important scenarios exist that impose limits to its successful adaptation. Here, we report a new approach for inducing enantioselectivity in transition-metal-catalysed reactions that relies on neutral hydrogen-bond donors (HBDs)5,6 that bind anions of cationic transition-metal complexes to achieve enantiocontrol and rate enhancement through ion pairing together with other non-covalent interactions7-9. A cooperative anion-binding effect of a chiral bis-thiourea HBD is demonstrated to lead to high enantioselectivity (up to 99% enantiomeric excess) in intramolecular ruthenium-catalysed propargylic substitution reactions10. Experimental and computational mechanistic studies show the attractive interactions between electron-deficient arene components of the HBD and the metal complex that underlie enantioinduction and the acceleration effect.

| S-EPMC10388379 | biostudies-literature

Mechanism-Guided Development of a Highly Active Bis-thiourea Catalyst for Anion-Abstraction Catalysis.

Project description:We describe the rational design of a linked, bis-thiourea catalyst with enhanced activity relative to monomeric analogues in a representative enantioselective anion-abstraction reaction. Mechanistic insights guide development of this linking strategy to favor substrate activation though the intramolecular cooperation of two thiourea subunits while avoiding nonproductive aggregation. The resulting catalyst platform overcomes many of the practical limitations that have plagued hydrogen-bond-donor catalysis and enables use of catalyst loadings as low as 0.05 mol %. Computational analyses of possible anion-binding modes provide detailed insight into the precise mechanism of anion-abstraction catalysis with this pseudo-dimeric thiourea.

| S-EPMC5380606 | biostudies-literature

Asymmetric Mannich synthesis of ?-amino esters by anion-binding catalysis.

Project description:We report a scalable, one-pot Mannich route to enantioenriched ?-amino esters by direct reaction of ?-chloroglycine ester as a practical imino ester surrogate. The reaction is promoted by a chiral aminothiourea, which is proposed to operate cooperatively by generating an iminium ion by chloride abstraction and an enolate by deprotonation, followed by highly stereoselective C-C bond formation between both reactive intermediates associated non-covalently within the catalyst framework.

| S-EPMC4183616 | biostudies-literature

Xanthene-4,5-diamine derivatives: a study of anion-binding catalysis.

Project description:This study describes the synthesis of a class of anion-binding catalysts based on a xanthene scaffold. Both unsymmetrical catalysts and C2-symmetrical catalysts were generated, and were examined in the cyclization of 3- and 2-substituted furans onto N-acyliminium ions. Good conversion for each reaction was observed with a variety of anion-binding catalysts (42-76%).

| S-EPMC4551103 | biostudies-literature

Enantioselective acylation of silyl ketene acetals through fluoride anion-binding catalysis.

Project description:A highly enantioselective acylation of silyl ketene acetals with acyl fluorides has been developed to generate useful α,α-disubstituted butyrolactone products. This transformation is promoted by a new thiourea catalyst and 4-pyrrolidinopyridine and represents the first example of enantioselective thiourea anion-binding catalysis with fluoride.

| S-EPMC3164931 | biostudies-literature

Insight into the Folding and Cooperative Multi-Recognition Mechanism in Supramolecular Anion-Binding Catalysis.

Project description:H-bond donor catalysts able to modulate the reactivity of ionic substrates for asymmetric reactions have gained great attention in the past years, leading to the development of cooperative multidentate H-bonding supramolecular structures. However, there is still a lack of understanding of the forces driving the ion recognition and catalytic performance of these systems. Herein, insight into the cooperativity nature, anion binding strength, and folding mechanism of a model chiral triazole catalyst is presented. Our combined experimental and computational study revealed that multi-interaction catalysts exhibiting weak binding energies (≈3-4 kcal mol-1 ) can effectively recognize ionic substrates and induce chirality, while strong dependencies on the temperature and solvent were quantified. These results are key for the future design of catalysts with optimal anion binding strength and catalytic activity in target reactions.

| S-EPMC7839480 | biostudies-literature

Enantioselective dearomatization of isoquinolines by anion-binding catalysis en route to cyclic α-aminophosphonates.

Project description:An enantioselective dearomatization of isoquinolines has been developed using chiral anion-binding catalysis. This transformation, catalyzed by a simple and easy to prepare tert-leucine-based thiourea derivative, makes use of silyl phosphite as a nucleophile and generates cyclic α-aminophosphonates. This is the first time asymmetric anion-binding catalysis has been applied to the synthesis of α-aminophosphonates.

| S-EPMC5465551 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data