Neutral dual hydrogen bond donors (HBDs) are effective catalysts that enhance the electrophilicity of substrates or the Lewis/Brønsted acidity of reagents through an anion-binding mechanism. Despite their success in various enantioselective organocatalytic reactions, their application to transition metal catalysis remains rare. Herein, we report the activation of gold(I) precatalysts by chiral ureas, leading to enantioselective hydroarylation of allenes with indoles. Experimental and computational studies support an anion-binding mechanism for gold(I) precatalyst activation. Noncovalent interactions were identified as the source of enantiodifferentiation, providing insights into the cooperativity between achiral phosphine ligands and chiral ureas.
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http://dx.doi.org/10.1016/j.tetlet.2024.155247 | DOI Listing |
Tetrahedron Lett
October 2024
Department of Chemistry, University of California, Berkeley, CA 94720, USA.
Neutral dual hydrogen bond donors (HBDs) are effective catalysts that enhance the electrophilicity of substrates or the Lewis/Brønsted acidity of reagents through an anion-binding mechanism. Despite their success in various enantioselective organocatalytic reactions, their application to transition metal catalysis remains rare. Herein, we report the activation of gold(I) precatalysts by chiral ureas, leading to enantioselective hydroarylation of allenes with indoles.
View Article and Find Full Text PDFChem Asian J
November 2024
School of Chemical Sciences, Indian Association for the Cultivation of Science, 2 A/2B Raja S.C Mullick Road, Jadavpur, Kolkata, West Bengal, 700 032, India.
Retrosynthetically designed and syntheses of three unprecedented core modified N-confused porphyrinoids exhibiting vis-NIR absorption with tunable aromaticity is reported. Controlled modification of types of oxidants (chloranil vs. DDQ) has led to the isolation of 18π-aromatic porphyrinoid 7 (upon chloranil oxidation) while DDQ oxidation has led to 18 e σ-aromatic porphyrinoids 8 and 9.
View Article and Find Full Text PDFNanoscale
November 2024
Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, UK.
Ion transport across biological membranes, facilitated by naturally occurring ion channels and pumps, plays a crucial role in biological processes. Gating is an important aspect of these systems, whereby transport is regulated by a range of external stimuli such as light, ligands and membrane potential. While synthetic ion transport systems, especially those with gating mechanisms, are rare, they have garnered significant attention due to their potential applications in targeted therapeutics as anticancer agents or to treat channelopathies.
View Article and Find Full Text PDFChem Asian J
January 2025
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
The importance of anions in various processes has led to a search for molecules that can effectively recognize and interact with these anions. This study explores how the tetraglycine [(Gly)] peptide in its zwitterionic, neutral, and terminally capped forms acts as a receptor for HPO and HSO anions within the framework of supramolecular host-guest chemistry. Using molecular dynamics (MD) simulations, we obtained the conformations of the receptor-anion complexes.
View Article and Find Full Text PDFChem Commun (Camb)
September 2024
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
This review article summarises work from the author's group on catalysis using coordination cages over the (approximate) period 2018-2024. Recent insights discussed include (i) the general mechanism of catalysis, which involves co-location of reaction partners using orthogonal interactions involving the cage cavity (neutral hydrophobic substrates) and the surface anion-based reaction partners; (ii) the role of the cage exterior surface in facilitating catalysis in some cases; (iii) quantitative analysis of anion-binding to the cage surface, as a complement to measurement of binding constants of neutral guests inside the cavity; (iv) a new type of redox-based catalysis using reactive oxygen species, which are generated by reaction of oxidants such as HO and HSO with Co(II)/Co(III) redox couples in the cage superstructure. Collectively the results discussed provide signficant new possibilities for further exploration of catalysis using supramolecular assemblies.
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