Readily Accessible Unsymmetrical Unsaturated 2,6-Diisopropylphenyl N-Heterocyclic Carbene Ligands. Applications in Enantioselective Catalysis

Tarrieu, Robert; Dumas, Adrien; Thongpaen, Jompol; Vivès, Thomas; Roisnel, Thierry; Dorcet, Vincent; Crévisy, Christophe; Baslé, Olivier; Mauduit, Marc

doi:10.1021/acs.joc.6b02888

Cited by 49 publications

(27 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although some advances have been achieved using phosphine ligands, their tedious synthesis and, in some cases, intrinsic ease of oxidation excludes practical applications on a large scale. In contrast, the rigid structure of NHCs (N-heterocyclic carbenes) provides an excellent opportunity to form stable gold complexes with a well-defined chiral environment, as was proven in the case of other metals, such as palladium [26][27][28][29], ruthenium [30][31][32][33] or copper [34][35][36][37][38][39][40][41][42]. Moreover, adequately planned structure of NHC ligands allows for tuning of their electronic and steric properties, which is not easily achievable in the case of phosphines [43,44].…”

Section: Introductionmentioning

confidence: 99%

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

Michalak

Kośnik

2019

Catalysts

View full text Add to dashboard Cite

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 C 2 and C 1 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. Scheme 3. The synthesis of a gold(I) complex from (R)-1-aminotetralin.An elegant approach to C2-symmetric gold(I) complexes was described by Czekelius et al. [72] (Scheme 4), inspired by previous Herrmann's work [73]. The synthetic approach involves chiral amines 24, readily available from the corresponding phenylacetic acid 22 via the Friedel-Crafts reaction of bromobenzene and fractional crystallization of the corresponding tartaric acid amine salt upon reductive amination. The resulting amine 24 was further formylated and subjected to Bischler-Napieralski cyclization to give 3-aryl-substituted dihydroisoquinoline 25. Subsequent reductive coupling afforded the basic diamine skeleton 26 into a single diastereomer, which appeared a perfect platform for structural ligand diversification via Suzuki coupling. The functionalized diamines 26 were then cyclized into imidazolium salts 27 with triethyl orthoformate to give the products with yields in the range of 49-94% (for selected examples, see Scheme 4). The formation of gold(I) complexes 28 was accomplished under rather unusual conditions, by the reaction of gold(I) chloride with a carbene generated by the action of KOtBu. Scheme 4. The synthesis of C2-symmetric gold(I) complexes accessible via a reductive coupling. The application of other chiral building blocks has recently been reported by the Toste group (Scheme 5) [74]. Besides chiral amines, amino alcohols 29 were also utilized in the synthesis of C2-Scheme 3. The synthesis of a gold(I) complex from (R)-1-aminotetralin.An elegant approach to C 2 -symmetric gold(I) complexes was described by Czekelius et al. [72] (Scheme 4), inspired by previous Herrmann's work [73]. The synthetic approach involves chiral amines 24, readily available from the corresponding phenylacetic acid 22 via the Friedel-Crafts reaction of bromobenzene and fractional crystallization of the corresponding tartaric acid amine salt upon reductive amination. The resulting amine 24 was further formylated and subjected to Bischler-Napieralski cyclization to give 3-aryl-substituted dihydroisoquinoline 25. Subsequent reductive coupling afforded the basic diamine skeleton 26 into a single diastereomer, which appeared a perfect platform for structural ligand diversification via Suzuki...

show abstract

Section: Introductionmentioning

confidence: 99%

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

Michalak

Kośnik

2019

Catalysts

View full text Add to dashboard Cite

show abstract

“…In 2017, Crévisy, Baslé, Mauduit, and co-workers reinvestigated this multicomponent synthetic protocol by examining various additives to increase the selectivity and yield of desired products. 43 In this case, sterically hindered and poorly reactive, in comparison to mesitylamine, 2,6-diisopropylaniline [111, DIPP = 2,6-(i-Pr) 2 C 6 H 3 ] was chosen as a model substrate. The addition of zinc chloride and magnesium sulfate appeared to be crucial to improve selectivity and yield of 2,6-diisopropylphenyl derivatives 112.…”

Section: Scheme 20 the Synthesis Of Mesityl-derived Imidazolium Saltsmentioning

confidence: 99%

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

Czerwiński¹,

Michalak

2019

Synthesis

View full text Add to dashboard Cite

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

show abstract

“…In 2017, Crévisy, Baslé and Mauduit reported a new procedure for the synthesis of NHC ligands L4a and L4b, which were applied in the copper-catalyzed asymmetric hydroboration reaction of α,β-unsaturated ester 9 to give 60-76% yields of chiral secondary alcohols 10 after oxidation, and with up to 87:13 er (Scheme 4). 16 Published at the same time, Yoshida et al described the catalytic application of a novel, planar chiral cyclic (amino)(ferrocenyl) carbene ligand with copper [(R)-12] ( Figure 2) in an enantioselective hydroboration. Combined with oxidation, β-hydroxy ester 13 was produced with >99% yield and in 80% ee (Scheme 5).…”

Section: αβ-Unsaturated Esters and Cyanidesmentioning

confidence: 99%

Recent Advances in Copper-Catalyzed Asymmetric Hydroboration of Electron-Deficient Alkenes: Methodologies and Mechanism

Chen

Whiting

2018

Synthesis

View full text Add to dashboard Cite

The efficient synthesis of enantioenriched organoboron compounds has been recognized as an important topic in recent years. As an update review, this article aims to select key achievements in copper-catalyzed, electron-deficient alkene enantioselective hydroboration methodologies since the beginning of 2017. In addition, it covers relevant mechanistic investigations developed over the last six years, as well as total synthesis applications for preparing 1,3-diols as important medicinal intermediates.1 Introduction2 Methodologies for Copper-Catalyzed Hydroboration2.1 α,β-Unsaturated Ketones and Imines2.2 α,β-Unsaturated Esters and Cyanides2.3 Aryl Alkenes and Alkyl Alkenes3 Mechanistic Investigations on the Copper-Catalyzed Hydroboration3.1 A Cu–BX2 Intermediate3.1.1 Experimental Analysis3.1.2 Borylative Difunctionalization Methodologies3.1.3 Density Functional Theory3.2 A Cu–H Intermediate3.3 Other Mechanistic Proposals4 Synthetic Applications: Chiral 1,3-Diols5 Conclusions and Outlook

show abstract

Readily Accessible Unsymmetrical Unsaturated 2,6-Diisopropylphenyl N-Heterocyclic Carbene Ligands. Applications in Enantioselective Catalysis

Cited by 49 publications

References 50 publications

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

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

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

Recent Advances in Copper-Catalyzed Asymmetric Hydroboration of Electron-Deficient Alkenes: Methodologies and Mechanism

Contact Info

Product

Resources

About