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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Enantioselective C–H Alkenylation of Ferrocenes with Alkynes by Half-Sandwich Scandium Catalyst

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(6), P. 2470 - 2476

Published: Feb. 2, 2021

The enantioselective C–H alkenylation of ferrocenes with alkynes is, in principle, a straightforward and atom-efficient route for the construction planar-chiral ferrocene scaffolds bearing alkene functionality but has remained scarcely explored to date. Here we report first time highly quinoline- pyridine-substituted by half-sandwich scandium catalyst. This protocol features broad substrate scope, high enantioselectivity, 100% atom efficiency, selectively affording new family N/alkene functionalities. mechanistic details have been clarified DFT analyses. use quinoline/alkene-functionalized product as chiral ligand asymmetric catalysis is also demonstrated.

Language: Английский

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Rare‐Earth‐Based Metal–Organic Frameworks as Multifunctional Platforms for Catalytic Conversion

Small, Journal Year: 2021, Volume and Issue: 17(22)

Published: Feb. 19, 2021

Abstract The development of catalytic conversion is very important for human society. In the process, metal–organic frameworks (MOFs) can be utilized to obtain effective catalysts their porous structures and adjustable properties. addition, introduction rare‐earth (RE) elements with unique properties realize good performances. Thus, RE‐MOF related are summarized. Due cooperation RE MOF structures, RE‐based MOFs used as promising or precursors/supports other in areas energy conversion, environmental governance, organic synthesis. These aggregated studies highlight RE‐MOFs candidates conversion.

Language: Английский

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Modular Access to Spiro-dihydroquinolines via Scandium-Catalyzed Dearomative Annulation of Quinolines with Alkynes

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(48), P. 20462 - 20471

Published: Nov. 23, 2021

The catalytic enantioselective construction of three-dimensional molecular architectures from planar aromatics such as quinolines is great interest and importance the viewpoint both organic synthesis drug discovery, but there still exist many challenges. Here, we report scandium-catalyzed asymmetric dearomative spiro-annulation with alkynes. This protocol offers an efficient selective route for spiro-dihydroquinoline derivatives containing a quaternary carbon stereocenter unprotected N–H group readily accessible diverse alkynes, featuring high yields, enantioselectivity, 100% atom-efficiency, broad substrate scope. Experimental density functional theory studies revealed that reaction proceeded through C–H activation 2-aryl substituent in quinoline by scandium alkyl (or amido) species followed alkyne insertion into Sc–aryl bond subsequent 1,2-addition resulting alkenyl to C═N unit moiety. work opens new avenue dearomatization quinolines, leading spiro were previously difficult access other means.

Language: Английский

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Rhodium-catalyzed enantioselective and diastereodivergent access to diaxially chiral heterocycles

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Aug. 3, 2023

N-N axially chiral biaryls represent a rarely explored class of atropisomers. Reported herein is construction diverse classes diaxially containing and C-N/C-C diaxes in distal positions excellent enantioselectivity diastereoselectivity. The axis the products provides handle toward solvent-driven diastereodivergence, as has been realized coupling large scope benzamides sterically hindered alkynes, affording complementary diastereodivergence elucidated by computational studies which revealed that hexafluoroisopropanol (HFIP) solvent molecule participated an unusual manner well ligand switched sequence two competing elementary steps, resulting switch stereoselectivity alkyne insertion inversion configuration C-C axis. Further cleavage N-directing group diaxial transforms to enantiodivergence.

Language: Английский

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C–H functionalization with alkenes, allenes, and alkynes by half-sandwich rare-earth catalysts

Tetrahedron, Journal Year: 2023, Volume and Issue: 135, P. 133323 - 133323

Published: Feb. 23, 2023

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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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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Regiodivergent C–H Alkylation of Quinolines with Alkenes by Half-Sandwich Rare-Earth Catalysts

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(42), P. 18128 - 18137

Published: Sept. 28, 2020

The regiodivergent catalysis of C–H alkylation with alkenes is great interest and importance but has remained hardly explored to date. We report herein the first quinolines by half-sandwich rare-earth catalysts. regiodivergence was achieved fine-tuning metal/ligand combination or steric electronic properties use C5Me5-ligated scandium catalyst Sc-3 for reaction styrenes that C5Me4H-ligated yttrium Y-2 aliphatic olefins exclusively afforded corresponding C8–H products, thus constituting example direct neutral quinolines. In contrast, Sc-3-catalyzed 2-arylquinolines Y-2-catalyzed selectively gave 2-aryl o-C–H products. On basis catalyst/substrate-controlled regiodivergence, sequential regiospecific dialkylation two different also been achieved. DFT studies revealed activation 2-phenylquinoline at both C8 position an ortho 2-phenyl substituent possible, these types initially formed products were interconvertible through coordination another molecule quinoline. regioselectivity reactions governed not only ease initial formation energy barriers their interconversions, as well influences in subsequent alkene insertion processes. This work constituted efficient protocol selective synthesis diversified quinoline derivatives offered unprecedented insights into transformation may help design more efficient, selective, complementary

Language: Английский

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Recent progress in rare-earth metal-catalyzed sp² and sp³ C–H functionalization to construct C–C and C–heteroelement bonds

Organic Chemistry Frontiers, Journal Year: 2022, Volume and Issue: 9(11), P. 3102 - 3141

Published: Jan. 1, 2022

The review presents rare-earth metal-catalyzed C(sp 2 /sp 3 )–H functionalization accessing C–C/C–heteroatom bonds and olefin (co)polymerization, highlighting substrate scope, mechanistic realization, origin of site-, enantio-/diastereo-selectivity.

Language: Английский

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