Chiral N-Heterocyclic Carbenes with Restricted Flexibility in Asymmetric Catalysis†

2007 ◽  
Vol 26 (3) ◽  
pp. 626-632 ◽  
Author(s):  
Denys Baskakov ◽  
Wolfgang A. Herrmann ◽  
Eberhardt Herdtweck ◽  
Stephan D. Hoffmann
Keyword(s):  
Asymmetric Catalysis ◽  
Heterocyclic Carbenes

Application of Nitrogen Heterocyclic Carbenes in Organocatalysis

2020 ◽  
Vol 09 ◽  
Author(s):  
Minita Ojha ◽  
R. K. Bansal
Keyword(s):  
Asymmetric Catalysis ◽  
Building Blocks ◽  
Structural Features ◽  
Heterocyclic Carbenes ◽  
Stetter Reaction ◽  
Metal Pollutants ◽  
Synthetic Strategy ◽  
Wide Range ◽  
Benzoin Condensation ◽  
Nitrogen Heterocyclic

Background: During the last two decades, horizon of research in the field of Nitrogen Heterocyclic Carbenes (NHC) has widened remarkably. NHCs have emerged as ubiquitous species having applications in a broad range of fields, including organocatalysis and organometallic chemistry. The NHC-induced non-asymmetric catalysis has turned out to be a really fruitful area of research in recent years. Methods: By manipulating structural features and selecting appropriate substituent groups, it has been possible to control the kinetic and thermodynamic stability of a wide range of NHCs, which can be tolerant to a variety of functional groups and can be used under mild conditions. NHCs are produced by different methods, such as deprotonation of Nalkylhetrocyclic salt, transmetallation, decarboxylation and electrochemical reduction. Results: The NHCs have been used successfully as catalysts for a wide range of reactions making a large number of building blocks and other useful compounds accessible. Some of these reactions are: benzoin condensation, Stetter reaction, Michael reaction, esterification, activation of esters, activation of isocyanides, polymerization, different cycloaddition reactions, isomerization, etc. The present review includes all these examples published during the last 10 years, i.e. from 2010 till date. Conclusion: The NHCs have emerged as versatile and powerful organocatalysts in synthetic organic chemistry. They provide the synthetic strategy which does not burden the environment with metal pollutants and thus fit in the Green Chemistry.

Synthesis of chiral iminoalkyl functionalised N-heterocyclic carbenes and their use in asymmetric catalysis

2007 ◽  
Vol 48 (50) ◽  
pp. 8914-8917 ◽  
Author(s):  
Mahboub Merzouk ◽  
Theo Moore ◽  
Neil A. Williams
Keyword(s):  
Asymmetric Catalysis ◽  
Heterocyclic Carbenes

From Prochiral N-Heterocyclic Carbenes (NHC) to Optically Pure Copper Complexes: New Opportunities in Asymmetric Catalysis

2019 ◽  
Author(s):  
Lingyu Kong ◽  
Jennifer Morvan ◽  
Delphine Pichon ◽  
Marion Jean ◽  
Muriel Albalat ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Copper Complexes ◽  
Pure Copper ◽  
Heterocyclic Carbenes ◽  
Allylic Alkylation ◽  
Chiral Hplc ◽  
Pure Cu ◽  
First Time ◽  
Optically Pure ◽  
Cu Complexes

Well-defined optically pure copper-complexes are obtained from prochiral N- Heterocyclic Carbene (NHC) ligands. As predicted by DFT calculations, our strategy capitalizes on the formation of a metal-carbene bond which induces axial chirality. Configurationally stable (Sa)- and (Ra)-atropisomers of various Cu-complexes are isolated by preparative chiral HPLC in nearly quantitative yields and excellent optical purities (>99.5%). Their catalytic performances are illustrated in asymmetric allylic alkylation with high regioselectivity and enantioinductions. Importantly, the carbene transfer from an optically pure Cu-complex to gold or palladium center reveals, for the first time, a full stereoretentivity, supporting the hypothesis of an associative mechanism for the transmetalation.

Chiral imidazo[1,5-a]tetrahydroquinoline N-heterocyclic carbenes and their copper complexes for asymmetric catalysis

2013 ◽  
Vol 24 (8) ◽  
pp. 492-498 ◽  
Author(s):  
Jin-Long Zhang ◽  
Liang-An Chen ◽  
Rui-Bin Xu ◽  
Chuan-Fei Wang ◽  
Yuan-Ping Ruan ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Copper Complexes ◽  
Heterocyclic Carbenes

scholarly journals Chiral N-heterocyclic Carbene Gold Complexes: Synthesis and Applications in Catalysis

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 890 ◽  
Author(s):  
Michalak ◽  
Kośnik
Keyword(s):  
Metal Complexes ◽  
Asymmetric Catalysis ◽  
Heterocyclic Carbenes ◽  
Present Review ◽  
Enantioselective Catalysis ◽  
Multiple Bonds ◽  
Gold Complexes ◽  
Metal Catalysis

N-Heterocyclic carbenes have found many applications in modern metal catalysis, due to the formation of stable metal complexes, and organocatalysis. Among a myriad of N-heterocyclic carbene metal complexes, gold complexes have gained a lot of attention due to their unique propensity for the activation of carbon-carbon multiple bonds, allowing many useful transformations of alkynes, allenes, and alkenes, inaccessible by other metal complexes. The present review summarizes synthetic efforts towards the preparation of chiral N-heterocyclic gold(I) complexes exhibiting C2 and C1 symmetry, as well as their applications in enantioselective catalysis. Finally, the emerging area of rare gold(III) complexes and their preliminary usage in asymmetric catalysis is also presented.

scholarly journals Modular Chiral N-Heterocyclic Carbene Ligands for the Nickel-Catalyzed Enantioselective C–H Functionalization of Heterocycles

2020 ◽  
Vol 74 (4) ◽  
pp. 278-284
Author(s):  
Johannes Diesel ◽  
Nicolai Cramer
Keyword(s):  
Transition Metals ◽  
Asymmetric Catalysis ◽  
Heterocyclic Carbenes ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Carbene Ligands ◽  
Active Compounds ◽  
Flexible Ligand ◽  
Mild Conditions ◽  
Bicyclic Compounds

N-Heterocyclic carbenes (NHCs) are the ligands of choice in a large variety of transformations entailing different transition metals. However, the number and variety of chiral NHCs suitable as stereo-controlling ligands in asymmetric catalysis remains limited. Herein we highlight the introduction of a modular NHC ligand family, consisting of a chiral version of the widely used IPr ligand. These chiral NHC ligands were applied in the nickel-catalyzed enantioselective C–H functionalization of N-heterocycles. Nickel-NHC catalysis unlocked the stereoselective C–H annulation of 2- and 4-pyridones, delivering fused bicyclic compounds found in many biologically active compounds. Applying a bulky, yet flexible ligand scaffold enabled the highly enantioselective C–H functionalization of pyridones under mild conditions. The introduction of a bulky chiral SIPr analogue enabled the nickel-catalyzed enantioselective C–H functionalization of indoles, yielding valuable tetrahydropyridoindoles. Additionally, pyrrolopyridines, pyrrolopyrimidines and pyrroles were efficiently functionalized, delivering chiral annulated azoles.

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