Harnessing Multistep Chalcogen Bonding Activation in the α-Stereoselective Synthesis of Iminoglycosides

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(15), P. 10608 - 10620

Published: April 2, 2024

The use of noncovalent interactions (NCIs) has received significant attention as a pivotal synthetic handle. Recently, the exploitation unconventional NCIs gained considerable traction in challenging reaction manifolds such glycosylation due to their capacity facilitate entry into difficult-to-access sugars and glycomimetics. While investigations involving oxacyclic pyrano- or furanoside scaffolds are relatively common, methods that allow selective synthesis biologically important iminosugars comparatively rare. Here, we report phosphonochalcogenide (PCH) catalyze stereoselective α-iminoglycosylation iminoglycals with wide array glycosyl acceptors remarkable protecting group tolerance. Mechanistic studies have illuminated counterintuitive role catalyst serially activating both donor acceptor up/downstream stages through chalcogen bonding (ChB). dynamic interaction chalcogens substrates opens up new mechanistic opportunities based on iterative ChB engagement disengagement multiple elementary steps.

Language: Английский

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Triethoxysilane-Catalyzed Single and Sequential Regioselective Hydroboration of Terminal Alkynes: Sustainable Access to E-Alkenylboronate and Alkyl Gem-Diboronate Esters by Non-Covalent Interactions

ACS Catalysis, Journal Year: 2025, Volume and Issue: unknown, P. 976 - 981

Published: Jan. 1, 2025

Triethoxysilane was found to be an efficient catalyst for the synthesis of E-alkenyl- and alkyl-di-boronate esters by single sequential hydroboration terminal alkynes, respectively, with pinacolborane. Mechanistic studies support that formation diboronate proceeds a double pathway steric electronic profile at Si being key enabling second step. Weak non-covalent interactions involving C≡C or C═C bonds in alkynes alkenylboronate have been identified as responsible substrate activation toward addition HBPin.

Language: Английский

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Stereoselective Entry into α,α’‐C‐Oxepane Scaffolds through a Chalcogen Bonding Catalyzed Strain‐Release C‐Septanosylation Strategy

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(29)

Published: April 30, 2024

Abstract The utility of unconventional noncovalent interactions (NCIs) such as chalcogen bonding has lately emerged a robust platform to access synthetically difficult glycosides stereoselectively. Herein, we disclose the versatility phosphonochalcogenide (PCH) catalyst facilitate into challenging, but biologically interesting 7‐membered ring α,α’‐ C ‐disubstituted oxepane core through an α‐selective strain‐release ‐glycosylation. Methodically, this strategy represents switch from more common entropically less desired macrocyclizations thermodynamically favored ring‐expansion approach. In light general lack stereoselective methods ‐septanosides, remarkable palette silyl‐based nucleophiles can be reliably employed in our method. This include broad variety useful synthons, easily available silyl‐allyl, silyl‐enol ether, silyl‐ketene acetal, vinylogous silyl‐alkyne and silylazide reagents. Mechanistic investigations suggest that mechanistic shift towards intramolecular aglycone transposition involving pentacoordinate silicon intermediate is likely responsible steering stereoselectivity.

Language: Английский

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A Blueprint for Secondary Coordination Sphere Editing: Approaches Toward Lewis‐Acid Assisted Carbon Dioxide Co‐Activation

ChemSusChem, Journal Year: 2024, Volume and Issue: 17(13)

Published: Feb. 15, 2024

Abstract Carbon dioxide (CO 2 ) is a potent greenhouse gas of environmental concern. Seeking to offer solution the “CO ‐problem”, chemistry community has turned focus toward transition metal complexes which can activate, reduce, and convert CO into carbon‐based products. The design such systems involves judicious selection both accompanying donor ligand; in part, these efforts are motivated by biological metalloenzymes that undertake similar transformations. As element, metal‐ligand cooperativity, leverages intramolecular interactions between an adjacent secondary ligand site, been acknowledged as vitally important component activation community. These “push‐pull” style where electron density chaperoned onto with electrophile, Lewis‐acid, playing role acceptor. This pairing allows for stabilization reactive C x H y O z ‐containing intermediates bias product selectivity. In laboratory, chemists test hypotheses ideas, enabling rationalization why given metal/Lewis‐acid leads selective reduction outcomes. Concept identifies literature examples highlights key properties, allowing interested contributors design, create, implement novel productive transformations small molecule huge potential impact.

Language: Английский

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Chalcogen- and Halogen-Bond-Donating Cyanoborohydrides Provide Imine Hydrogenation

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(5), P. 2916 - 2925

Published: Feb. 19, 2024

Sulfonium, selenonium, telluronium, and iodonium cyanoborohydrides have been synthesized, isolated, fully characterized by various methods, including single-crystal X-ray diffraction (XRD) analysis. The quantum theory of atoms in molecules' analysis based on the XRD data indicated that hydride···σ-hole short contacts observed crystal structures each compound a purely noncovalent nature. telluronium provide significantly higher rate model reaction imine hydrogenation compared with sodium tetrabutylammonium cyanoborohydrides. Based NMR high-resolution electrospray ionization mass spectrometry indicating progress is accompanied cation reduction, mechanism involving intermediate formation elusive onium hydrides has proposed as an alternative to conventional electrophilic activation moiety its ligation cation's σ-hole.

Language: Английский

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Noncovalent Interactions Steer the Formation of Polycyclic Aromatic Hydrocarbons

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(33), P. 23022 - 23033

Published: Aug. 7, 2024

Aromatic molecules play an important role in the chemistry of astronomical environments such as cold interstellar medium (ISM) and (exo)planetary atmospheres. The observed abundances (polycyclic) aromatic hydrocarbons benzonitrile cyanonaphthalenes are, however, highly underestimated by astrochemical models. This demonstrates need for more experimentally verified reaction pathways. low-temperature ion–molecule benzonitrile•+ with acetylene is studied here using a multifaceted approach involving kinetics spectroscopic probing products. A fast radiative association via situ prereactive complex shows importance noncovalent interactions steering pathway during reactions. Product structures subsequent reactions are unambiguously identified infrared action spectroscopy reveal formation nitrogen-containing, linked bicyclic phenylpyridine•+ benzo-N-pentalene+ structures. results, contradicting earlier assumptions on product structure, demonstrate products emphasize possible environments.

Language: Английский

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Cationic Hypervalent Chalcogen Bond Catalysis on the Povarov Reaction: Reactivity and Stereoselectivity

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(24)

Published: Feb. 19, 2024

Abstract Chalcogen bond catalysis, particularly cationic hypervalent chalcogen is considered to be an effective strategy for organocatalysis. In this work, the catalysis Povarov reaction between N‐benzylideneaniline and ethyl vinyl ether was investigated by density functional theory (DFT). The catalytic involves cycloaddition process proton transfer process, rate‐determining step process. Cationic tellurium derivatives bearing CF 3 F groups exhibit superior activity. For step, Gibbs free energy barrier decreases as positive electrostatic potential of catalysts increases. More importantly, has a strong linear correlation with in catalyst‐substrate complex. Furthermore, reactions include endo pathway exo pathway. C−H⋅⋅⋅π interaction substituent aryl ring contributes endo‐selectivity reaction. This research deeper understanding providing insights designing high performance.

Language: Английский

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Substituent Effect on Chalcogen Bonding in 5-Substituted Benzo[c][1,2,5]selenadiazoles and Their Copper(II) Complexes: Experimental and Theoretical Study

Crystal Growth & Design, Journal Year: 2023, Volume and Issue: 24(2), P. 781 - 791

Published: Dec. 27, 2023

In parallel to the nature of chalcogen atom (Ch) and nucleophile (Nu), strength directionality bonding (ChB) are also dependent on electron donor or acceptor character functional group (R) at ∠R–Ch···Nu. Although Hammett's para-substituent constant (σp) can be used for quantitative description substituent effects, herein, we found that due participation substituents in various types intermolecular interactions, there is no linear relationship between σp R (X = −CH3, −H, −F, −Cl, −Br, −NO2) experimental Se···N distance ∠N–Se···N angle 5-substituted benzo[c][1,2,5]selenadiazoles their copper(II) complexes. Such a not observed theoretically, which rationalized by taking into consideration formation intramolecular hydrogen bonds Cu The have been analyzed using quantum theory "atoms molecules" combined with noncovalent interaction plot energy decomposition analysis.

Language: Английский

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Asymmetric amino acid-based homogeneous catalysts

Elsevier eBooks, Journal Year: 2025, Volume and Issue: unknown, P. 95 - 124

Published: Jan. 1, 2025

Language: Английский

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Oxidant-free annulation of α-hydroxy ketones with diamines using aluminum(III) chloride: A supramolecular approach for practical quinoxaline synthesis

Results in Chemistry, Journal Year: 2025, Volume and Issue: unknown, P. 102148 - 102148

Published: Feb. 1, 2025

Language: Английский

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