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

---

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

---

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

ChemCatChem, Journal Year: 2022, Volume and Issue: 14(23)

Published: Oct. 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.

Language: Английский

---

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

---

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

---

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

Science China Chemistry, Journal Year: 2023, Volume and Issue: 66(6), P. 1804 - 1813

Published: May 10, 2023

Language: Английский

---

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, Journal Year: 2023, Volume and Issue: 145(31), P. 17468 - 17477

Published: July 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.

Language: Английский

---

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

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(32)

Published: April 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.

Language: Английский

---

Rare‐Earth Metal Alkyl Complexes Featuring Bridged Bis(β‐Diketiminato) Ligand: Synthesis, Structure, and Catalytic Activity for Intramolecular Hydroamination Reaction

Applied Organometallic Chemistry, Journal Year: 2025, Volume and Issue: 39(1)

Published: Jan. 1, 2025

ABSTRACT A series of rare‐earth metal alkyl complexes containing chiral cyclohexyl‐bridged bis( β ‐diketiminate) ligands have been synthesized, with a general chemical formula {Cy[NC (Me)CHC (Me)NAr] 2 }RECH SiMe 3 [Cy=(1R, 2R)‐(‐)‐1,2‐cyclohexyl, Ar=2,6‐ i Pr C 6 H , RE=Dy( 1 ), Er( Yb( Y( 4 )]. These compounds were prepared in good yields by the reaction RE[CH ] (THF) Cy[NHC ( L ). Comprehensive characterizations all achieved through spectroscopic methods and elemental analysis. The structures Compounds – determined single‐crystal x‐ray diffraction analysis, Compound was further characterized hydrogen‐1 H) NMR carbon‐13 13 C) spectroscopy. catalytic performance these investigated, their ability to catalyze hydroamination/cyclization aminoalkenes afford corresponding cyclic amines proven. resulting heterocyclic predominantly Markovnikov addition products. efficiency different catalysts not significantly affected central metal, over 90% conversion could be catalyst loading as low 3%. However, six‐membered ring products found more challenging compared formation five‐membered rings.

Language: Английский

---

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

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

Published: April 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.

Language: Английский

---