Supramolecularly fine-regulated enantioselective catalysts

Vaquero, M. Pilar; Rovira, Laura; Vidal‐Ferran, Anton

doi:10.1039/c6cc04474c

Cited by 42 publications

(22 citation statements)

References 67 publications

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“…Chemists are at the beginning of building synthetic catalysts with similar functions, with the long‐term aim to control chemical pathways in more complex chemical mixtures . In this context, there is increasing interest in synthetic catalysts that can be switched by external stimuli or cofactors . Most of these studies have been carried out using relatively simple hydrolysis reactions and organocatalytic reactions, and the number of transition‐metal catalysts that have a switching function is very limited .…”

Section: Figurementioning

confidence: 99%

Cofactor Controlled Encapsulation of a Rhodium Hydroformylation Catalyst

Jongkind

Elemans²,

Reek

2019

Angewandte Chemie

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Supramolecular approaches in transition‐metal catalysis, including catalyst encapsulation, have attracted considerable attention. Compared to enzymes, supramolecular catalysts in general are less complex. Enzyme activity is often controlled by the use of smaller cofactor molecules, which is important in order to control reactivity in complex mixtures of molecules. Interested in increasing complexity and allowing control over supramolecular catalyst formation in response to external stimuli, we designed a catalytic system that only forms an efficient supramolecular complex when a small cofactor molecule is added to the solution. This in turn affects both the activity and selectivity when applied in a hydroformylation reaction. This contribution shows that catalyst encapsulation can be controlled by the addition of a cofactor, which affects crucial catalyst properties.

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Section: Figurementioning

confidence: 99%

Cofactor Controlled Encapsulation of a Rhodium Hydroformylation Catalyst

Jongkind

Elemans²,

Reek

2019

Angewandte Chemie

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“…Nowadays, countless examples support the efficacy of catalytic systems whose cohesion is ensured by weak interactions. Among them, those based on hydrogen bonding4 and coordination chemistry, are the most popular, but systems based on other types of attractive interactions (ion‐dipole, electrostatic or ionic hydrogen bond) also proved to be successful to design effective catalysts. Of interest, catalytic systems that make use of hydrophobic effects proved to be especially suitable for the conversion of hydrophobic substrates under aqueous biphasic conditions.…”

Section: Introductionmentioning

confidence: 99%

Pillar5arenes as Supramolecular Hosts in Aqueous Biphasic Rhodium‐Catalyzed Hydroformylation of Long Alkyl‐chain Alkenes

et al. 2018

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Aqueous biphasic catalysis continues to attract strong interest, especially when very hydrophobic substrates are concerned. Indeed, their insolubility in water strongly limit their transformation by water‐soluble organometallic catalysts. To improve contacts between the substrate‐containing organic phase and the catalyst‐containing phase, one of the best solutions consists in using interfacial additives capable of supramolecularly recognize the substrate and/or the catalyst. In the present study, modified pillar5arenes are considered as interfacial additives and their performance is assessed in Rh‐catalyzed hydroformylation of long alkyl‐chain alkenes (higher olefins). Pillar5arenes substituted by carboxylate functions and methyl groups P5 A‐(Me)10‐x‐(CH2COOMe)x are compared to pillar5arenes substituted by polyethylene glycol (PEG) chains (P5 A‐(Me)5‐(PEG)5 and P5 A‐(PEG)10). Utilization of P5 A‐(Me)10‐x‐(CH2COOMe)x leads to high conversion and regioselectivity (linear/branched aldehyde ratio) in Rh‐catalyzed hydroformylation of 1‐decene and 1‐hexadecene. Compared with other interfacial additives such as modified cyclodextrins, the studied pillar5arenes show lower chemo‐selectivity, similar catalytic activity and higher regioselectivity.

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“…[12][13][14][15][16] Recently,control of axial chirality in a tropos ligand was demonstrated by association of small chiral molecules through hydrogen bonding. [17,18] In this manner, ab y-design nonlinear amplification of stereoselectivity was achieved.Self-assembly ligand systems have also been used successfully in asymmetric catalysis, [19] and the necessary asymmetric induction has so far been achieved using building blocks with either chiral P-donors [20][21][22][23] or an axially chiral biphenyl moiety as as tereoregulating unit. [24] Theg roups of Raynal and Vidal-Ferran achieved stereocontrol through the coassembly of chiral benzene-1,3,5-tricarboxamides (BTA) with achiral BTAs functionalized with P-donor moieties in ahelical scaffold.…”

mentioning

confidence: 99%

Inducing Axial Chirality in a Supramolecular Catalyst

2018

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A new type of ligand, which is able to form axially chiral, supramolecular complexes was designed using DFT calculations. Two chiral monomers, each featuring a covalently bound chiral auxiliary, form a bidentate phosphine ligand with a twisted, hydrogen-bonded backbone upon coordination to a transition metal center which results in two diastereomeric, tropos complexes. The ratio of the diastereomers in solution is very temperature- and solvent-dependent. Rhodium and platinum complexes were analyzed through a combination of NMR studies, ESI-MS measurements, as well as UV-VIS and circular dichroism spectroscopy. The chiral self-organized ligands were evaluated in the rhodium-catalyzed asymmetric hydrogenation of α-dehydrogenated amino acids and resulted in good conversion and high enantioselectivity. This research opens the way for new ligand designs based on stereocontrol of supramolecular assemblies through stereodirecting chiral centers.

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Supramolecularly fine-regulated enantioselective catalysts

Cited by 42 publications

References 67 publications

Cofactor Controlled Encapsulation of a Rhodium Hydroformylation Catalyst

Cofactor Controlled Encapsulation of a Rhodium Hydroformylation Catalyst

Pillar5arenes as Supramolecular Hosts in Aqueous Biphasic Rhodium‐Catalyzed Hydroformylation of Long Alkyl‐chain Alkenes

Inducing Axial Chirality in a Supramolecular Catalyst

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