Chiral Cyclometalated Oxazoline Gold(III) Complex-Catalyzed Asymmetric Carboalkoxylation of Alkynes

Jiang, Jia; Cui, Jian‐Fang; Yang, Bin; Ning, Yulu; Lai, Nathanael Chun Him; Wong, Man Leung

doi:10.1021/acs.orglett.9b02171

Cited by 35 publications

(30 citation statements)

References 60 publications

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“…Although the enantioselectivity level was far from practical (Scheme 35), especially in comparison to the bisphosphine ligand used in the seminal work of Toste [122], the high yield proved excellent catalytic activity. Recently, Wong proved that formation of indanone 183 could catalyzed by the cyclometalated gold(III) complexes 184 [123].…”

Section: Furan Pyrrolidine and Indanone Derivativesmentioning

confidence: 99%

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

Michalak

Kośnik

2019

Catalysts

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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...

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Section: Furan Pyrrolidine and Indanone Derivativesmentioning

confidence: 99%

“…Catalysts 2019, 9, x FOR PEER REVIEW 26 of 40 catalytic activity. Recently, Wong proved that formation of indanone 183 could catalyzed by the cyclometalated gold(III) complexes 184[123]. The synthesis of indanone via carboalkoxylation.…”

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confidence: 99%

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

Michalak

Kośnik

2019

Catalysts

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“…The study of Au(III) chemistry is much more challenging both experimentally and theoretically, because these complexes are usually very reactive and difficult to synthesize. However, in recent years, many studies on the catalytic efficiency of Au(III) have been carried out, motivated by the expected more efficient activation of double and triple C-C bonds due to the larger Lewis acidity of the metal in its +3 oxidation state [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. First studies were devoted to synthesize stable Au(III) complexes.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of the Pre-Equilibrium Step in the Alkyne Hydration Reaction Catalyzed by Au(III) Complexes: A Computational Study Based on Experimental Evidences

et al. 2021

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The coordination ability of the [(ppy)Au(IPr)]2+ fragment [ppy = 2-phenylpyridine, IPr = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] towards different anionic and neutral X ligands (X = Cl−, BF4−, OTf−, H2O, 2-butyne, 3-hexyne) commonly involved in the crucial pre-equilibrium step of the alkyne hydration reaction is computationally investigated to shed light on unexpected experimental observations on its catalytic activity. Experiment reveals that BF4− and OTf− have very similar coordination ability towards [(ppy)Au(IPr)]2+ and slightly less than water, whereas the alkyne complex could not be observed in solution at least at the NMR sensitivity. Due to the steric hindrance/dispersion interaction balance between X and IPr, the [(ppy)Au(IPr)]2+ fragment is computationally found to be much less selective than a model [(ppy)Au(NHC)]2+ (NHC = 1,3-dimethylimidazol-2-ylidene) fragment towards the different ligands, in particular OTf− and BF4−, in agreement with experiment. Effect of the ancillary ligand substitution demonstrates that the coordination ability of Au(III) is quantitatively strongly affected by the nature of the ligands (even more than the net charge of the complex) and that all the investigated gold fragments coordinate to alkynes more strongly than H2O. Remarkably, a stabilization of the water-coordinating species with respect to the alkyne-coordinating one can only be achieved within a microsolvation model, which reconciles theory with experiment. All the results reported here suggest that both the Au(III) fragment coordination ability and its proper computational modelling in the experimental conditions are fundamental issues for the design of efficient catalysts.

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“…In 2019, Wong's group reported another work of asymmetric gold(III) catalysis by using chiral O,O‐chelated biphenol/C,N‐cyclometallated oxazoline gold(III) complexes (Scheme 41). [57] When biphenol was employed as the ligand in replace of BINOL, the O,O‐chelation mode was adopted without tautomerization. By screening of a series of (O,O)/(C,N)‐gold(III) catalysts and (C,O)/(C,N)‐gold(III) complexes, the authors found the chirality of BINOL or biphenol ligands contribute little to the reaction enantioselectivity, while the enantioselectivity is mainly related to the chiral substituent group on the oxazoline ligand.…”

Section: Recent Development Of Enantioselective Gold(iii) Catalysismentioning

confidence: 99%

Recent Advances in the Development of Chiral Gold Complexes for Catalytic Asymmetric Catalysis

Jiang

Wong

2021

Chemistry An Asian Journal

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Asymmetric gold catalysis has been rapidly developed in the past ten years. Breakthroughs have been made by rational design and meticulous selection of chiral ligands. This review summarizes newly developed gold‐catalyzed enantioselective organic transformations and recent progress in ligand design (since 2016), organized according to different types of chiral ligands, including bisphosphine ligands, monophosphine ligands, phosphite‐derived ligands, and N‐heterocyclic carbene ligands for asymmetric gold(I) catalysis as well as heterocyclic carbene ligands and oxazoline ligands for asymmetric gold(III) catalysis.

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Chiral Cyclometalated Oxazoline Gold(III) Complex-Catalyzed Asymmetric Carboalkoxylation of Alkynes

Cited by 35 publications

References 60 publications

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

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

Monitoring of the Pre-Equilibrium Step in the Alkyne Hydration Reaction Catalyzed by Au(III) Complexes: A Computational Study Based on Experimental Evidences

Recent Advances in the Development of Chiral Gold Complexes for Catalytic Asymmetric Catalysis

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