Application of Chiral Olefin Ligands in Asymmetric Catalysis

Feng, Xiujuan; Du, Haifeng

doi:10.6023/cjoc201409026

Cited by 15 publications

(7 citation statements)

References 24 publications

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“…This review focuses on the advances in the chemistry of chiral diene ligands starting with the first effective chiral diene ligand for asymmetric catalysis, which opened new avenues for the development of asymmetric processes . Prior to our compilation, several elegant reviews partially covered this subject. − Herein, we comprehensively summarize the development of chiral diene ligands by covering the literature published from August 2003 (when the first effective chiral diene ligand for asymmetric catalysis was reported) to October 2021. The major representative chiral diene ligands frequently employed in asymmetric catalysis with high efficiency are summarized in Figure .…”

Section: Introductionmentioning

confidence: 99%

Chiral Diene Ligands in Asymmetric Catalysis

Huang

Hayashi

2022

Chem. Rev.

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Asymmetric catalysis has emerged as a general and powerful approach for constructing chiral compounds in an enantioselective manner. Hence, developing novel chiral ligands and catalysts that can effectively induce asymmetry in reactions is crucial in modern chemical synthesis. Among such chiral ligands and catalysts, chiral dienes and their metal complexes have received increased attention, and a great progress has been made over the past two decades. This review provides comprehensive and critical information on the essential aspects of chiral diene ligands and their importance in asymmetric catalysis. The literature covered ranges from August 2003 (when the first effective chiral diene ligand for asymmetric catalysis was reported) to October 2021. This review is divided into two parts. In the first part, the chiral diene ligands are categorized according to their structures, and their preparation methods are summarized. In the second part, their applications in asymmetric transformations are presented according to the reaction types.

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Section: Introductionmentioning

confidence: 99%

Chiral Diene Ligands in Asymmetric Catalysis

Huang

Hayashi

2022

Chem. Rev.

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“…Based on our previous work involving the development of acyclic chiral diene ligands for transition-metal catalysis, we proposed a novel strategy for generating chiral boranes in situ by the hydroboration of chiral terminal dienes or diynes with Piers’ borane without further purification (Scheme ). In other words, chiral dienes or diynes can act like ligands.…”

Section: Introductionmentioning

confidence: 99%

Frustrated Lewis Pairs Catalyzed Asymmetric Metal-Free Hydrogenations and Hydrosilylations

2017

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The use of frustrated Lewis pairs is an extremely important approach to metal-free hydrogenations. In contrast to the rapid growth of catalytic reactions, asymmetric hydrogenations are far less developed due to a severe shortage of readily available chiral frustrated Lewis pair catalysts with high catalytic activities and selectivities. Unlike the stable Lewis base component of frustrated Lewis pairs, the moisture-sensitive boron Lewis acid component is difficult to prepare. The development of convenient methods for the quick construction of chiral boron Lewis acids is therefore of great interest. In this Account, we summarize our recent studies on frustrated Lewis pair-catalyzed, asymmetric metal-free hydrogenations and hydrosilylations. To address the shortage of highly active and selective catalysts, we developed a novel strategy for the in situ preparation of chiral boron Lewis acids by the hydroboration of chiral dienes or diynes with Piers' borane without further purification, which allows chiral dienes or diynes to act like ligands. This strategy ensures the construction of a useful toolbox of catalysts for asymmetric metal-free hydrogenations and hydrosilylations is rapid and operationally simple. Another strategy is using combinations of readily available Lewis acids and bases containing hydridic and acidic hydrogen atoms, respectively, as a novel type of frustrated Lewis pairs. Such systems provide a great opportunity for using simple chiral Lewis bases as the origins of asymmetric induction. With chiral diene-derived boron Lewis acids as catalysts, a broad range of unsaturated compounds, such as imines, silyl enol ethers, 2,3-disubstituted quinoxalines, and polysubstituted quinolines, are all viable substrates for asymmetric metal-free hydrogenations and give the corresponding products in good yields with high enantioselectivities and/or stereoselectivities. These chiral catalysts are very effective for bulky substrates, and the substrate scope for these metal-free asymmetric hydrogenations has been dramatically expanded. Chiral alkenylboranes were designed to enhance the rigidity of the framework and modify the Lewis acidity through the resulting double bonds. Frustrated Lewis pairs of chiral alkenylboranes and phosphines are a class of highly effective catalysts for asymmetric Piers-type hydrosilylations of 1,2-dicarbonyl compounds, and they give the desired products in high yields and enantioselectivities. Moreover, asymmetric transfer hydrogenations of imines and quinoxalines with ammonia borane as the hydrogen source have been achieved with frustrated Lewis pair of Piers' borane and (R)-tert-butylsulfinamide as the catalyst. Mechanistic studies have suggested that the hydrogen transfer occurs via an 8-membered ring transition state, and regeneration of the reactive frustrated Lewis pair with ammonia borane occurs through a concerted 6-membered ring transition state.

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“…To explore the potential utility of axially chiral styrenes, a series of transformations were conducted (Scheme ). The developed asymmetric Friedel–Crafts reaction could be performed on a gram scale.…”

Section: Results and Discussionmentioning

confidence: 99%