SPOs as Non‐Innocent Ligands in Chiral‐at‐Iridium Catalyzed Asymmetric Hydrogenations DOI Creative Commons
Ariadna Pazos, Zoraida Freixa

ChemCatChem, Journal Year: 2024, Volume and Issue: 16(20)

Published: June 18, 2024

Abstract A series of bis‐cyclometalated chiral‐at‐metal iridium(III) complexes containing a coordinated secondary phosphine oxide (SPO) have been synthesized and evaluated as catalysts in the asymmetric transfer hydrogenation (ATH) acetophenone. The catalytic results show that SPO ligands non‐innocent role activating process. Additionally, it has observed for same chiral descriptor (Δ‐at‐Ir or Λ‐at‐Ir), major enantiomer formed depends on nature cyclometalating ligand. These enantiodivergent contravene general assumption core‘s chirality dictates sense induction. combined analysis main structural features deduced from XRD structures situ NMR spectroscopy allowed us to propose simplified cycle working hypothesis explain enantioselectivities.

Language: Английский

Recent Developments in Enantioselective Transition Metal Catalysis Featuring Attractive Noncovalent Interactions between Ligand and Substrate DOI Creative Commons

Alexander Fanourakis,

Philip J. Docherty,

Padon Chuentragool

et al.

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(18), P. 10672 - 10714

Published: Aug. 14, 2020

Enantioselective transition metal catalysis is an area very much at the forefront of contemporary synthetic research. The development processes that enable efficient synthesis enantiopure compounds unquestionable importance to chemists working within many diverse fields central science. Traditional approaches solving this challenge have typically relied on leveraging repulsive steric interactions between chiral ligands and substrates in order raise energy one diastereomeric states over other. By contrast, Review examines alternative tactic which a set attractive noncovalent operating are used control enantioselectivity. Examples where creative approach has been successfully applied render fundamental enantioselective presented discussed. In cases examined, ligand scaffold carefully designed accommodate these interactions, while others, critical was only elucidated subsequent computational mechanistic studies. Through exploration discussion recent reports encompassing wide range reaction classes, we hope inspire continue develop asymmetric transformations based powerful concept.

Language: Английский

Citations

162
Metal Stereogenicity in Asymmetric Transition Metal Catalysis DOI Creative Commons

Philipp S. Steinlandt,

Lilu Zhang,

Eric Meggers

et al.

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(8), P. 4764 - 4794

Published: March 29, 2023

Chiral transition metal catalysts represent a powerful and economic tool for implementing stereocenters in organic synthesis, with the center providing strong chemical activation upon its interaction substrates or reagents, while overall chirality of complex achieves desired stereoselectivity. Often, chiral topology implements stereogenic center, which is then involved origin asymmetric induction. This review provides comprehensive survey reported formally constitutes stereocenter. A goes along an complex, regardless whether ligands are achiral. Implications catalyst design mechanism induction discussed half-sandwich, tetracoordinated, pentacoordinated, hexacoordinated complexes containing center. The distinguishes between originating from coordination to those solely composed optically inactive (achiral rapidly interconverting enantiomers) prior complexation (dubbed “chiral-at-metal” catalysts).

Language: Английский

Citations

87
Chiral-at-metal catalysts: history, terminology, design, synthesis, and applications DOI Creative Commons

Lilu Zhang,

Eric Meggers

Chemical Society Reviews, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Chiral-at-metal catalysts, containing only achiral ligands, utilize the metal as sole stereogenic center and catalytic center. They represent an emerging powerful class of chiral transition catalysts for asymmetric catalysis.

Language: Английский

Citations

2
A diversity of recently reported methodology for asymmetric imine reduction DOI Creative Commons
Jonathan Barrios-Rivera, Yingjian Xu, Martin Wills

et al.

Organic Chemistry Frontiers, Journal Year: 2020, Volume and Issue: 7(20), P. 3312 - 3342

Published: Jan. 1, 2020

This review describes recent developments in enantioselective imine reduction, including related substrates which a CN bond is the target for and in situ methods.

Language: Английский

Citations

62
Cycloiridated Helicenes as Chiral Catalysts in the Asymmetric Transfer Hydrogenation of Imines DOI
Daisuke Sakamoto,

Isabel Gay Sánchez,

Jiří Rybáček

et al.

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(17), P. 10793 - 10800

Published: Aug. 19, 2022

The asymmetric synthesis of optically pure and conformationally locked oxabenzo[5]helicenes bearing pyridin-2-yl or isoquinolin-3-yl substituents their transformation into the corresponding cycloiridated organometallics are described. These helically chiral Cp*IrIII(X)C,N-complexes (X = Cl, I) also contain a configurationally unstable pseudotetrahedral iridium center. This center undergoes epimerization at room temperature, its relative stereochemistry, especially in solid state, depends on nature coordinated ligands. Cycloiridated helicenes were used transfer hydrogenation prochiral aromatic imines with formic acid/triethylamine to reach up 96:4 er. It is assumed that chirality controlled by auxiliary helix rather than IrIII stereogenic iridacycles.

Language: Английский

Citations

32
Unmasking the reverse reactivity of cyclic N-sulfonyl ketimines: multifaceted applications in organic synthesis DOI
Soumitra Guin, Debashis Majee, Sampak Samanta

et al.

Chemical Communications, Journal Year: 2021, Volume and Issue: 57(72), P. 9010 - 9028

Published: Jan. 1, 2021

This feature article covers the recent status on reactivities of α-alkyl cyclic N -sulfonyl ketimines as resourceful nucleophiles, targeting fused carbo- and heterocycles, aza-arenes etc . In addition, mechanistic studies have been presented.

Language: Английский

Citations

35
Enhanced Catalytic Activity of Iridium(III) Complexes by Facile Modification of C,N-Bidentate Chelating Pyridylideneamide Ligands DOI
Miquel Navarro, Christene A. Smith, Martin Albrecht

et al.

Inorganic Chemistry, Journal Year: 2017, Volume and Issue: 56(19), P. 11688 - 11701

Published: Sept. 12, 2017

A set of aryl-substituted pyridylideneamide (PYA) ligands with variable donor properties owing to a pronounced zwitterionic and neutral diene-type resonance structure were used as electronically flexible at pentamethylcyclopentadienyl (Cp*) iridium center. The straightforward synthesis this type ligand allows for an easy incorporation substituents such methoxy groups in different positions the phenyl ring C,N-bidentate chelating PYA. These modifications considerably enhance catalytic activity coordinated center toward aerobic transfer hydrogenation carbonyls imines well hydrosilylation phenylacetylene. Moreover, these PYA complexes catalyze base-free aldehydes, lesser extent also ketones. Under standard conditions including base, aldehydes are rapidly oxidized carboxylic acids rather than reduced corresponding alcohol, is observed under conditions.

Language: Английский

Citations

44
Ruthenacycles and Iridacycles as Transfer Hydrogenation Catalysts DOI Creative Commons
Vincent Ritleng, Johannes G. de Vries

Molecules, Journal Year: 2021, Volume and Issue: 26(13), P. 4076 - 4076

Published: July 3, 2021

In this review, we describe the synthesis and use in hydrogen transfer reactions of ruthenacycles iridacycles. The review limits itself to metallacycles where a ligand is bound bidentate fashion either ruthenium or iridium via carbon-metal sigma bond, as well dative bond from heteroatom an N-heterocyclic carbene. Pincer complexes fall outside scope. Described are applications (asymmetric) hydrogenation aldehydes, ketones, imines, reductive aminations. Oxidation reactions, i.e., classical Oppenauer oxidation, which reverse hydrogenation, dehydrogenations oxidations with oxygen, described. Racemizations alcohols secondary amines also catalyzed by

Language: Английский

Citations

28
Lewis Acid‐Catalyzed Reductive Amination of Aldehydes and Ketones with N,N‐Dimethylformamide as Dimethylamino Source, Reductant and Solvent DOI
Luo Yang, Jie Lin, Lei Kang

et al.

Advanced Synthesis & Catalysis, Journal Year: 2017, Volume and Issue: 360(3), P. 485 - 490

Published: Nov. 14, 2017

Abstract A practical zinc acetate dihydrate‐catalyzed reductive amination of various carbonyl compounds with N , ‐dimethylformamide (DMF) as dimethylamino (Me 2 N) source, reductant and solvent has been developed. This reaction shows broad substrate scope, good functional group tolerance, avoids the need for a pressure‐proof reactor column chromatographic isolation operations gives up to 98% yield, make it an attractive method preparation tertiary ‐dimethylamines. magnified image

Language: Английский

Citations

35
Nickel-Catalyzed Asymmetric Transfer Hydrogenation and α-Selective Deuteration ofN-Sulfonyl Imines with Alcohols: Access to α-Deuterated Chiral Amines DOI
Peng Yang, Li Zhang,

Kaiyue Fu

et al.

Organic Letters, Journal Year: 2020, Volume and Issue: 22(21), P. 8278 - 8284

Published: Oct. 12, 2020

A nickel-catalyzed enantioselective transfer hydrogenation and deuteration of N-sulfonyl imines was developed. Excellent α-selectivity high deuterium content were achieved by using inexpensive 2-propanol-d8 as a source. As highlight, no β-C-H the remote C-H amines occurred, which is hard to achieve other or hydrogen isotope exchange with D2O. Mechanism studies indicated stepwise pathway through [Ni-D] intermediate.

Language: Английский

Citations

24