Enantioselective [3+2] Annulation of Aldimines with Alkynes by Scandium‐Catalyzed C−H Activation

Angewandte Chemie International Edition, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 3, 2025

Abstract The enantioselective [3+2] annulation of readily accessible aldimines with alkynes via C−H activation is, in principle, a straightforward and atom‐efficient route for synthesizing chiral 1‐aminoindenes, which are important components wide array natural products, bioactive molecules, functional materials. However, such asymmetric transformation has remained undeveloped to date due the lack suitable catalysts. Here, we report first time using half‐sandwich scandium This protocol enabled synthesis diverse multi‐substituted 1‐aminoindene derivatives 100 % atom‐efficiency, broad substrate scope, high regio‐ enantioselectivity. Density theory (DFT) analyses have revealed that noncovalent C−H⋅⋅⋅π interaction between tert ‐Bu substituent cyclopentadienyl (Cp) ligand phenyl ring an aromatic aldimine played role achieving level work not only offers efficient selective new family but also unprecedented insights into enantioselectivity control Cp‐ligated metal

Language: Английский

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Anti-Markovnikov hydroallylation reaction of alkenes via scandium-catalyzed allylic C‒H activation

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: Feb. 6, 2025

Compared with rare-earth (RE)…heteroatom interaction, RE…π frequently used in facilitating regio- and stereoselectivity of olefin polymerizations, is seldomly to trigger catalytic C - H functionalization. Here, we describe a direct anti-Markovnikov hydroallylation reaction styrene derivatives 1-aryl-2-alkyl alkenes α-alkenes by use interaction. This protocol provides straightforward atom-efficient route for the synthesis valuable chain elongated internal (65 examples, up 99% yield, > 19:1 E/Z ratio). The proceeds via an allylic Csp3‒H activation pathway initiated site-selective deprotonation assistance cationic imidazolin-2-iminato scandium alkyl species followed alkene insertion into resulting scandium-allyl bond. A amount Lewis base additives, such as amine tetrahydrofuran (THF) show significant effects on reactivity selectivity. mechanism elucidated experimental studies theoretical calculations.

Language: Английский

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Unleashing the potentiality of metals: synergistic catalysis with light and electricity

Organic Chemistry Frontiers, Journal Year: 2024, Volume and Issue: 11(14), P. 4024 - 4040

Published: Jan. 1, 2024

This review provides a comprehensive overview of metal catalysis in photo-electrochemical systems, discussing reaction mechanisms and offering prospects for this triadic catalytic mode.

Language: Английский

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Divergent Synthesis of Multi‐Substituted Aminotetralins via [4+2] Annulation of Aldimines with Alkenes by Rare‐Earth‐Catalyzed Benzylic C(sp³)−H Activation

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(13)

Published: Jan. 16, 2024

The search for efficient and selective methods the divergent synthesis of multi-substituted aminotetralins is much interest importance. We report herein first time diastereoselective [4+2] annulation 2-methyl aromatic aldimines with alkenes via benzylic C(sp

Language: Английский

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Rare Earths—The Answer to Everything

Molecules, Journal Year: 2024, Volume and Issue: 29(3), P. 688 - 688

Published: Feb. 1, 2024

Rare earths, scandium, yttrium, and the fifteen lanthanoids from lanthanum to lutetium, are classified as critical metals because of their ubiquity in daily life. They present magnets cars, especially electric cars; green electricity generating systems computers; steel manufacturing; glass light emission materials for safety lighting lasers; exhaust catalysts supports; artificial rubber production; agriculture animal husbandry; health cancer diagnosis treatment; a variety electronic products essential modern living. have potential replace toxic chromates corrosion inhibition, magnetic refrigeration, new materials, role may expand. This review examines sustainability, environment, recycling, crop production, feedstocks, catalysis, health, well considering future uses.

Language: Английский

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Regio- and Diastereoselective Annulation of α,β-Unsaturated Aldimines with Alkenes via Allylic C(sp³)–H Activation by Rare-Earth Catalysts

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(14), P. 10187 - 10198

Published: March 28, 2024

The [3 + 2] or [4 annulation of α,β-unsaturated aldimines with alkenes via β′- γ-allylic C(sp3)–H activation is, in principle, an atom-efficient route for the synthesis five- six-membered-ring cycloalkylamines, which are important structural motifs numerous natural products, bioactive molecules, and pharmaceuticals. However, such a transformation has remained undeveloped to date probably due lack suitable catalysts. We report herein first time regio- diastereoselective annulations imines allylic by half-sandwich rare-earth catalysts having different metal ion sizes. reaction α-methyl-substituted C5Me4SiMe3-ligated scandium catalyst took place trans-diastereoselective fashion at α-methyl group (β′-position), exclusively affording alkylidene-functionalized cyclopentylamines excellent trans-diastereoselectivity. In contrast, β-methyl-substituted C5Me5-ligated cerium proceeded cis-diastereoselective activation, selectively yielding multisubstituted 2-cyclohexenylamines cis-diastereoselectivity. mechanistic details these transformations have been elucidated deuterium-labeling experiments, kinetic isotope effect studies, isolation key intermediates. This work offers efficient selective protocol new family cycloalkylamine derivatives, featuring 100% atom efficiency, high diastereoselectivity, broad substrate scope, unprecedented mechanism.

Language: Английский

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Theoretical Insights into Rare-Earth-Catalyst-Controlled Diastereo- and Enantioselective [3 + 2] Annulation of Aromatic Aldimines with Styrenes

Inorganic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 5, 2025

Rare-earth-catalyzed annulation reactions using alkenes via C–H activation offer an atom-efficient approach to constructing cyclic compounds. However, the mechanisms underlying these remain poorly understood, limiting rational design of related catalytic systems. Recently, Hou and Cong reported unprecedented example rare-earth-catalyst-controlled diastereodivergent asymmetric [3 + 2] aromatic aldimines with alkenes. To elucidate origins diastereo- enantioselectivity, density functional theory calculations were performed. The results revealed that styrene insertion step determines stereoselectivity. Styrene follows a similar metal–styrene interaction pattern across different catalysts. Specifically, during cis-insertion, interacts strongly metal center, exhibiting significant Sc···Ph interactions, whereas such interactions are absent trans-insertion. Thus, when catalyst is employed small ligand, stereoselectivity primarily governed by electronic factors, favoring cis-insertion mode. In contrast, for more sterically hindered catalyst, in insufficient overcome steric effects, leading preference trans-insertion mode, which minimizes hindrance. These findings deeper insights into catalyst-controlled enantioselectivity will also contribute stereospecific rare-earth catalysis.

Language: Английский

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Elucidating the mechanism and origin of diastereoselectivity in scandium-catalyzed β-C(sp³)–H activation and transformation of an aliphatic aldimine

Organic Chemistry Frontiers, Journal Year: 2024, Volume and Issue: 11(16), P. 4391 - 4401

Published: Jan. 1, 2024

The mechanism and origin of regio- diastereoselectivity in the reaction divergent [3 + 2] annulation aliphatic aldimines with alkenes by scandium-catalyzed β-C(sp 3 )–H activation have been revealed detail using DFT calculations.

Language: Английский

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(Z)-Selective Isomerization of 1,1-Disubstituted Alkenes by Scandium-Catalyzed Allylic C–H Activation

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(39), P. 26766 - 26776

Published: Sept. 20, 2024

The isomerization of 1,1-disubstituted alkenes through 1,3-hydrogen shift is an atom-efficient route for synthesizing trisubstituted alkenes, which are important moieties in many natural products, pharmaceuticals, and organic materials. However, this reaction often encounters regio- stereoselectivity challenges, typically yielding

Language: Английский

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Regio- and Stereoselective Hydroalkynylation of Internal Alkynes with Terminal Alkynes by Half-Sandwich Rare-Earth Catalysts

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 5, 2025

The regio- and stereoselective hydroalkynylation of internal alkynes with terminal is great interest importance as a straightforward route for synthesizing multisubstituted 1,3-enynes. However, this transformation often suffers from stereoselectivity issues when working unsymmetrical alkynes. Herein, we report the first time syn-stereoselective variety heteroatom-functionalized including homopropargyl ethers, thioethers, tertiary amines by half-sandwich rare-earth catalysts. This protocol provides an atom-efficient synthesis new family heteroatom (O, S, or N)-functionalized 1,3-enynes, featuring 100% atom-efficiency, broad substrate scope, high syn-stereoselectivity (>19:1 r.r. >19:1 syn/anti). mechanistic details have been elucidated deuterium-labeling experiments, control isolation transformations key reaction intermediates, revealing that proceeded through C(sp)–H deprotonation alkyne scandium alkyl species to form catalytically active dimeric tetraalkynyl followed heteroatom-assisted insertion into Sc–alkynyl bond subsequent protonolysis resulting Sc–alkenyl another molecule. coordination N) catalyst metal center plays critically important role in achieving level reactivity stereoselectivity. Remarkably, can be recovered reused, constituting example recyclable system

Language: Английский

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