New Optically Active <i>N</i>-Heterocyclic Carbene Complexes for Hydrogenation:  A Tale with an Atropisomeric Twist

Chen, Dianjun; Banphavichit, Vorawit; Reibenspies, Joseph; Burgess, Kevin

doi:10.1021/om061013+

Cited by 31 publications

(12 citation statements)

References 38 publications

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“…[170] The application of 101 to the hydrogenation of more complex functionalised dienes has also been described, [171,172] whilst a pyrimidine analogue was recently described. [173] In direct line with the work of Burgess, Pfaltz has reported a library approach to 2-and 4-oxazoline-NHC cationic Ir I complexes (Scheme 21). A large number of imidazolium precursors were generated (e.g., 102 and 103) and the NHC-Ir I complexes were tested in the hydrogenation of a range of di-and trisubstituted alkenes, with results (essentially complete conversions at 1 mol-% loading, ee values up to 90 %) approaching those obtained with 101 and the best SimplePHOX ligand.…”

Section: Asymmetric Olefin Hydrogenation (Rh Ir)mentioning

confidence: 88%

Donor‐Functionalised N‐Heterocyclic Carbene Complexes of Group 9 and 10 Metals in Catalysis: Trends and Directions

2008

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This review focuses on the latest advances in homogeneous catalysis with donor‐functionalised (donor = C, N, O, S or P) N‐heterocyclic carbene complexes of group 9 and 10 metals. The applications of such complexes to C–C coupling reactions, alkyne and ketone hydrosilylation, olefin polymerisation, transfer hydrogenation, asymmetric hydrogenation and other catalysed reactions are discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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Section: Asymmetric Olefin Hydrogenation (Rh Ir)mentioning

confidence: 88%

Donor‐Functionalised N‐Heterocyclic Carbene Complexes of Group 9 and 10 Metals in Catalysis: Trends and Directions

2008

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“…Compounds such as 16 could be examined as organocatalyst [27] and other pyridine or pyrimidine derivatives of this study are possibly interesting ligands of chiral catalysts. [3,28] As particular attractive feature, the 4-hydroxyproline derived heterocycles offer the option of immobilization of these catalysts at a polymeric support. [29] indicated; chemical shifts (δ) are given in ppm relative to residual solvent peaks, coupling constants (J) are given in Hz.…”

Section: Discussionmentioning

confidence: 99%

A Proline and 4‐Hydroxyproline Based Approach to Enantiopure Pyrrolidin‐2‐yl‐Substituted Pyridine and Pyrimidine Derivatives

et al. 2021

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The optimized coupling of N-protected (S)-proline and (2S,4R)-4-hydroxyproline derivatives with (Z)-4-aminopent-3-en-2-one provided the expected β-ketoenamides in good to excellent yields. The subsequent intramolecular cyclizations afforded enantiopure pyridin-4-one derivatives with pyrrolidin-2-yl substituents. The nonaflates generated from these intermediates were excellent precursors for typical palladium-catalyzed coupling reactions. Oxidation with m-chloroperbenzoic acid gave pyrrolidine N-oxides whose subsequent reactions were inves-tigated. The condensation of β-ketoenamides with hydroxylamine hydrochloride furnished the corresponding enantiopure pyrimidine N-oxides in good yields. The subsequent Boekelheide rearrangement provided hydroxymethyl-substituted pyrimidine derivatives together with minor components. Overall, this study nicely demonstrates the potential of (S)-proline-or (2S,4R)-4-hydroxyproline-derived β-ketoenamides to approach a library of novel chiral pool-derived enantiopure functionalized pyridine and pyrimidine derivatives.

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“…In 2007, Burgess and co-workers presented a protocol for the synthesis of triazolium salts with a pyrimidine unit (Scheme 42). 82 Notably, the synthesis of compounds bearing a shorter methylene bridge between the triazole and pyrimidine subunits failed due to epimerization in the condensation reaction between the 1,3-diketone or ynone with amidines.…”

Section: Scheme 41 the Synthesis Of Triazolium Salts From Cyclic Aminmentioning

confidence: 99%

Synthetic Approaches to Chiral Non-C 2-symmetric N-Heterocyclic Carbene Precursors

Czerwiński¹,

Michalak

2019

Synthesis

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N-Heterocyclic carbenes and their metal complexes have found applications in many organic transformations. Apart from the privileged C 2-symmetry present in modern enantioselective catalysis, ligands bearing C 1-symmetry have witnessed growing attention due to the better control of process stereoselectivity in many cases. The present review summarizes, for the first time, the seminal synthetic efforts for the preparation of N-heterocyclic carbene precursors exhibiting C 1-symmetry. The well-established methods will be discussed in the light of recent achievements, giving a direct opportunity for comparison of the existing methods, and simultaneously a chance to find the best synthetic pathway for the ideal chiral ligand.1 Introduction2 Five-Membered Rings2.1 Five-Membered Saturated (Imidazolinium) Ring2.1.1 Amino Alcohol Derivatives2.1.2 Amino Acid Derivatives2.1.3 Amine and Diamine Derivatives2.2 Five-Membered Unsaturated Ring2.2.1 Cyclization Strategy2.2.2 Functionalization of the Existing N-Imidazole Ring3 Triazolium Salts3.1 Substitution in Oxadiazolium Salts3.2 Lactam-Derived Triazolium NHC (The Leeper and Knight Methodology)3.3 Monoterpenoid-Derived NHC Triazolium Salts3.4 Modifications of the Existing Triazole Ring4 Thiazole-Derived Salts4.1 Cyclization of a Thiazolium Ring4.2 Modifications of the Existing Thiazole Ring5 Summary and Outlook

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New Optically Active N-Heterocyclic Carbene Complexes for Hydrogenation: A Tale with an Atropisomeric Twist

Cited by 31 publications

References 38 publications

Donor‐Functionalised N‐Heterocyclic Carbene Complexes of Group 9 and 10 Metals in Catalysis: Trends and Directions

Donor‐Functionalised N‐Heterocyclic Carbene Complexes of Group 9 and 10 Metals in Catalysis: Trends and Directions

A Proline and 4‐Hydroxyproline Based Approach to Enantiopure Pyrrolidin‐2‐yl‐Substituted Pyridine and Pyrimidine Derivatives

Synthetic Approaches to Chiral Non-C 2-symmetric N-Heterocyclic Carbene Precursors

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