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

Tetrahedron, Год журнала: 2023, Номер 135, С. 133323 - 133323

Опубликована: Фев. 23, 2023

Язык: Английский

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Recent Advances in Rare‐Earth Metal‐Catalyzed C−H Functionalization Reactions

ChemCatChem, Год журнала: 2022, Номер 14(23)

Опубликована: Окт. 12, 2022

Abstract There has been a persistent impetus for the development of versatile C−H functionalization reactions, which represents powerful approach to wide variety valuable chemical compounds. Transition metal catalyzed attracted intense interest and witnessed considerable advances in this field owing its outstanding regioselectivity atom‐economy. In recent years, rare‐earth (RE) metal‐based catalysts have successfully employed flourished area, demonstrating unique selectivity complementary reactivity with respect late‐transition metal‐catalyzed functionalization. The by taking advantage these characteristic properties is great importance interest. Herein, panorama during last decade presented.

Язык: Английский

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C-H alkylation of pyridines with olefins catalyzed by imidazolin-2-iminato-ligated rare-earth alkyl complexes

Science China Chemistry, Год журнала: 2023, Номер 66(6), С. 1804 - 1813

Опубликована: Май 10, 2023

Язык: Английский

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Enantioselective Synthesis of 1-Aminoindanes via [3 + 2] Annulation of Aldimines with Alkenes by Scandium-Catalyzed C–H Activation

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(31), С. 17468 - 17477

Опубликована: Июль 28, 2023

Multisubstituted chiral 1-aminoindanes are important components in many pharmaceuticals and bioactive molecules. Therefore, the development of efficient selective methods for synthesis is great interest importance. In principle, asymmetric [3 + 2] annulation aldimines with alkenes through C–H activation most atom-efficient straightforward route construction 1-aminoindanes, but such a transformation has remained undeveloped to date probably due lack suitable catalysts. Herein, we report first time enantioselective wide range aromatic via ortho-C(sp2)–H by half-sandwich scandium catalysts, which provides multisubstituted 1-aminoindanes. This protocol features 100% atom-efficiency, broad functional group compatibility, high regio-, diastereo-, enantioselectivity (up >19:1 dr 99:1 er). Remarkably, fine-tuning sterics ligand around catalyst metal center, diastereodivergent styrenes been achieved level diastereo- enantioselectivity, offering an method both trans cis diastereomers novel class 1-aminoindane derivatives containing two contiguous stereocenters from same set starting materials. Moreover, aliphatic α-olefins, norbornene, 1,3-dienes also achieved.

Язык: Английский

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The Effect of Basic Ligands and Alkenes on the Regioselectivity of C−H Additions of Tertiary Amines to Alkenes

Chemistry - A European Journal, Год журнала: 2024, Номер 30(32)

Опубликована: Апрель 4, 2024

Abstract Highly regioselective C−H alkylation reactions of tertiary anilines and alkyl amines with simple alkenes have been achieved by the use imidazolin‐2‐iminato scandium complexes. This protocol provided an efficient atom‐economical route to structurally diverse amine derivatives. The basic ligand, a coordinating THF in catalyst substitution alkene substrates were found switch regioselectivity presumably due generation different types catalytically active species or formation relatively stable intermediates. On basis deuterium labeling experiments KIE experiments, possible catalytical cycles understand reaction mechanism as well regioselectivity.

Язык: Английский

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Enantioselective ortho-C–H Addition of Aromatic Amines to Alkenes by Bulky Chiral Anilido-Oxazoline Scandium Complexes

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Апрель 8, 2025

The enantioselective C-H addition of anilines to alkenes represents an ideal protocol for the synthesis chiral aromatic amines in terms step- and atom-economy. However, this field remains predominantly unexplored. Herein, a series newly designed bulky anilido-oxazoline ligand precursors were synthesized, corresponding rare-earth metal alkyl complexes obtained successfully. resultant scandium exhibit high regioselectivity ortho-C-H tertiary unactivated alkenes, providing wide range alkylated yields (up 98% yield) with excellent enantioselectivity ee). Moreover, products can be easily converted into biorelevant derivatives pharmacophore-containing skeletons.

Язык: 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, Год журнала: 2023, Номер 62(2), С. 979 - 988

Опубликована: Янв. 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

Язык: Английский

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Substrate Facilitating Roles in Rare-Earth-Catalyzed C–H Alkenylation of Pyridines with Allenes: Mechanism and Origins of Regio- and Stereoselectivity

Inorganic Chemistry, Год журнала: 2022, Номер 61(43), С. 17330 - 17341

Опубликована: Окт. 19, 2022

Although considerable progress has been achieved in C-H functionalization by cationic rare-earth alkyl complexes, the potential facilitating roles of heteroatom-containing substrates during catalytic cycle remain highly underestimated. Herein, theoretical studies on model reaction C(sp2)-H addition pyridines to allenes scandium catalyst were carefully carried out reveal detailed mechanism. A coordinating pyridine substrate as a ligand can effectively stabilize some key structures. An obvious role delivered was found for allene insertion, while pyridine-free mechanism prefers occur activation processes. Importantly, elusive systematically revealed event designing metal/ligand combination catalysts and substrates. We that pyridyl would be switched pyridine-coordinated cases designed Y La catalysts. To date, this is first time realize substrate-facilitating rare-earth-catalyzed Moreover, predictions show similar switchable mechanisms also work other types bonds heteroatom-involved fine-adjusting steric surroundings The two are mainly result delicate balance between electronic factors. In general, system with less hindrance undergo substrate-coordinated contrast, substrate-free favorable due repulsion. These results helpful us better understand variant at atomistic level may help guide rational design new reactions. addition, origins regio- stereoselectivity discussed through geometric parameters distortion/interaction analysis.

Язык: Английский

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De novo three-component synthesis of meta-substituted anilines

Organic Chemistry Frontiers, Год журнала: 2023, Номер 10(11), С. 2760 - 2765

Опубликована: Янв. 1, 2023

A metal- and additive-free reaction of easily accessible N -acylpyridinium iodides, methylvinyl ketones amines provides access to meta -substituted anilines.

Язык: Английский

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Divergent Synthesis of (E)- and (Z)-Alkenones via Photoredox C(sp³)–H Alkenylation–Dehydrogenation of o-Iodoarylalkanols with Alkynes

Organic Letters, Год журнала: 2024, Номер 26(47), С. 10096 - 10101

Опубликована: Ноя. 15, 2024

A photoredox C(sp3)–H alkenylation–dehydrogenation of o-iodoarylalkanols with terminal alkynes for the synthesis (E)- and (Z)-quaternary carbon center-containing pent-4-en-1-ones is described. The stereoselectivity depends on utilization photocatalysts. While using an organic photocatalyst like 4-DPAIPN manipulates arylalkynes to assemble (E)-pent-4-en-1-ones, in case Ir potocatalyst such as Ir(ppy)2(dtbbpy)PF6 reaction delivers (Z)-pent-4-en-1-ones. For alkylalkynes, furnishes (E)-pent-4-en-1-ones exclusively presence or Ir(ppy)2(dtbbpy)PF6.

Язык: Английский

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