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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Mechanisms and Origins of Regioselectivity in Rare-Earth-Catalyzed C–H Functionalization of Anisoles and Thioanisoles

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

Published: March 12, 2025

The direct catalytic C–H functionalization of aromatic compounds such as anisoles and thioanisoles is great interest significance. However, achieving precise regioselectivity remains a major challenge. In this study, we conducted comprehensive density functional theory calculations to explore the mechanisms rare-earth-catalyzed regioselective alkylation, borylation, silylation anisole thioanisole. results reveal that in cationic alkylation systems, alkene insertion step follows substrate-assisted mechanism, which an additional substrate molecule acts ligand facilitate transformation. neutral borylation although mononuclear hydride species readily dimerize into binuclear due thermodynamic stability, process predominantly proceeds via pathway. Furthermore, origins were thoroughly elucidated. A detailed analysis electronic steric effects related transition states reveals that, for anisole, primarily governed by ring strain. Since α-C(sp3)–H activation involves formation highly strained three-membered ring, reaction preferentially occurs at ortho-C(sp2)–H site, forming less four-membered ring. contrast, thioanisole, play decisive role, driving more negatively charged α-C(sp3) site stronger metal–carbon interactions.

Language: Английский

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Unveiling the Detailed Mechanism and Origins of Chemo-, Regio-, and Stereoselectivity of Rare-Earth Catalyzed Alternating Copolymerization of Polar and Nonpolar Olefins

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(7), P. 3544 - 3559

Published: Feb. 3, 2024

The direct copolymerization of polar and nonpolar olefins is great interest significance, as it the most atom-economical straightforward strategy for synthesis functional polyolefin materials. Despite considerable efforts, precise control monomer-sequence their regio- stereochemistry full challenges, related mechanistic origins are still in infancy to date. Herein, studies on model reaction Sc-catalyzed co-syndiospecific alternating anisylpropylene (AP) styrene were performed by DFT calculations. results suggest that subtle balance between electronic steric factors plays an important role during monomer insertions, a new amino-dissociated mechanism was proposed AP insertion at chain initiation. follows 2,1-si-insertion pattern, which mainly controlled caused restricted MeO···Sc interaction. As insertion, prefers 2,1-re-insertion manner its stereoselectivities influenced repulsions inserting polymer or ligand. More interestingly, found determined "steric matching" principle, quantitatively expressed buried volume metal center preinserted species. concept pocket has been successfully applied explain different performances several catalysts other reactions. insightful findings quantitative present here expected promote rational design rare-earth developing regio-, stereo-, sequence-controlled specific olefins.

Language: Английский

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Mechanistic Insights into Rare-Earth-Catalyzed Alternating Copolymerization through C–H Polyaddition of Functionalized Organic Compounds to Unconjugated Dienes

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(18), P. 8079 - 8091

Published: April 25, 2024

Density functional theory (DFT) calculations have been conducted to elucidate the detailed mechanisms of yttrium-catalyzed C–H polyaddition 1,4-dimethoxybenzene (DMB) 1,4-divinylbenzene (DVB). It was computationally determined that DMB not only serves as a substrate but also performs crucial role ligand, stabilizing catalytically active species and promoting alkene insertion. Side pathways involving Cβ–H activation C═C continuous insertion were excluded due steric electronic factors, respectively, explaining why reaction occurred efficiently selectively give perfectly alternating DMB–DVB polymers. Interestingly, theoretical prediction reactivity N,N-dimethyl-1,4-phenylenediamine 2,2′-biethyl-4,4′-bipyridine reveals significant differences in coordination effects these substrates, leading distinct mechanisms, primarily influenced by their effects. These findings shed new light on previously overlooked ligand rare-earth-catalyzed step-growth copolymerization reactions.

Language: Английский

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Overlooked Ligand Role of Pyridine Substrate in Site Selectivity of Rare-Earth-Catalyzed C–H Alkylation with Alkenes

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

Published: April 11, 2025

The rare-earth-catalyzed C-H alkylation of heteroatom-containing substrates with alkenes has been extensively studied over the past decade. Traditionally, those have regarded primarily as reactants in these reactions. In this study, mechanism 2-ethylpyridine styrene was investigated by DFT calculations, revealing often-overlooked ligand effect pyridine substrates. Our findings demonstrate that substrates, acting ligands, play a pivotal role modulating site selectivity during activation. These results enhance our understanding rare-earth catalysis and provide valuable insights into its versatile reactivity, offering novel perspective on dual roles (both reactant ligand) which are widely used functionalization

Language: Английский

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Mechanism and Origin of Site Selectivity and Regioselectivity of Scandium-Catalyzed Benzylic C–H Alkylation of Tertiary Anilines with Alkenes

Inorganic Chemistry, Journal Year: 2023, Volume and Issue: 62(2), P. 979 - 988

Published: Jan. 5, 2023

Benzylic C(sp3)-H alkylation of tertiary anilines with alkenes by an anilido-oxazoline-ligated scandium alkyl catalyst was recently reported C-H site selectivity and alkene-dependent regioselectivity. Revealing the mechanism origin is undoubtedly great importance for understanding experimental observations developing new reactions. Herein, density functional theory (DFT) calculations have been carried out on model reaction Sc-catalyzed benzylic N,N-dimethyl-o-toluidine allylbenzene. The generally undergoes generation active species, alkene insertion, protonation steps. difference distortion energy aniline moiety in transition states, which related to ring size forming metallacycles, accounts activation. activation possessing less strained five-membered metallacycle compared ortho-C(sp2)-H α-methyl results observed experimentally. Both steric electronic factors are responsible 1,2-insertion regioselectivity alkyl-substituted alkenes, while control 2,1-insertion manner vinylsilanes. analysis original substrates further strengthens These help us obtain mechanistic expected be conducive development functionalization

Language: Английский

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Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

Beilstein Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 19, P. 820 - 863

Published: June 12, 2023

Pyridine is a crucial heterocyclic scaffold that widely found in organic chemistry, medicines, natural products, and functional materials. In spite of the discovery several methods for synthesis functionalized pyridines or their integration into an molecule, new methodologies direct functionalization pyridine scaffolds have been developed during past two decades. addition, transition-metal-catalyzed C–H rare earth metal-catalyzed reactions flourished over decades development molecules concern. this review, we discuss recent achievements transition-metal bond look mechanisms involved.

Language: Английский

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Mechanistic Investigation on Potassium Amide-Catalyzed Benzylic C–H Bond Addition of Alkylpyridines to Styrenes

Organometallics, Journal Year: 2024, Volume and Issue: 43(4), P. 526 - 531

Published: Feb. 2, 2024

The catalytic C–H bond addition of alkylpyridines to olefins represents one the most efficient approaches alkyl-substituted pyridine derivatives with 100% atom-economy efficiency. Various catalysts including late transition metal, early and s-block metal complexes displayed rich versatile activity. Potassium amide could selectively achieve benzylic alkylation alkylpyridines, displaying distinct activity regioselectivity. Here, mechanistic investigation via both kinetic experiments DFT calculations revealed dimer structure potassium confirmed a deprotonative functionalization process.

Language: Английский

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Rare-earth metal bis(alkyl) amidopyridinate complexes in dehydrocoupling of anisole with hydrosilanes

Russian Chemical Bulletin, Journal Year: 2024, Volume and Issue: 73(10), P. 2872 - 2882

Published: Oct. 1, 2024

Language: Английский

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Six-membered ring systems: pyridines and benzo derivatives

Progress in heterocyclic chemistry, Journal Year: 2023, Volume and Issue: unknown, P. 383 - 425

Published: Jan. 1, 2023

Language: Английский

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