Primary–Tertiary Diamine/Brønsted Acid Catalyzed C–C Coupling between <i>para</i>‐Vinylanilines and Aldehydes

Cui, Lingyun; Zhu, Yunbo; Luo, Sanzhong; Cheng, Jiang

doi:10.1002/chem.201300995

Cited by 16 publications

(6 citation statements)

References 47 publications

(33 reference statements)

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“…Therefore, we limited our discussions to those with explicit C–H bond activation or C–H bond cleavage as the key product-determining steps. The typical Heck-type processes as well as electron-tuning alkene functionalization reactions, such as reactions with enamine, enamide, or aromatic enamines, are also excluded. − …”

Section: Sp2 C–h Bond Functionalizationmentioning

confidence: 99%

Organocatalysis in Inert C–H Bond Functionalization

2017

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As two coexisting and fast-growing research fields in modern synthetic chemistry, the merging of organocatalysis and C-H bond functionalization is well foreseeable, and the joint force along this line has been demonstrated to be a powerful approach in making inert C-H bond functionalization more viable, predictable, and selective. In this review, we provide a comprehensive summary of organocatalysis in inert C-H bond functionalization over the past two decades. The review is arranged by types of inert C-H bonds including alkane C-H, arene C-H, and vinyl C-H as well as those activated benzylic C-H, allylic C-H, and C-H bonds alpha to the heteroatom such as nitrogen and oxygen. In each section, the discussion is classified by the explicit organocatalytic mode involved.

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Section: Sp2 C–h Bond Functionalizationmentioning

confidence: 99%

Organocatalysis in Inert C–H Bond Functionalization

2017

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“…Alkenes are seldom utilized in conjugate addition reactions because of their low nucleophilicity as well as the uncontrolled side reactions accompanying such processes. We recently found that p -vinylanilines 33 , endowed with an intervening aromatic ring between the amine and vinyl group, demonstrated nucleophilic reactivity closely resembling that of typical enamines . These alkene nucleophiles were also tested in the enantioselective α-protonation reaction .…”

Section: Enantioselective Transformations Of α-Branched Vinyl Ketonesmentioning

confidence: 99%

Pushing the Limits of Aminocatalysis: Enantioselective Transformations of α-Branched β-Ketocarbonyls and Vinyl Ketones by Chiral Primary Amines

2015

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Enantioselective α-functionalizations of carbonyl compounds are fundamental transformations for the asymmetric synthesis of organic compounds. One of the more recent developments along this line is in aminocatalysis, which leads to the direct α-functionalization of simple aldehydes and ketones. However, most of the advances have been achieved with linear aldehydes and ketones as substrates. Effective aminocatalysis with α-branched carbonyls, particularly α-branched ketones, has remained elusive. The primary difficulty arises from the space-demanding α-substituent, which impedes iminium/enamine formation. In 2005, synthetic organic chemists revived catalysis using primary amines, which brought new attention to these challenges, because of the conformational flexibility of primary amines. On the basis of early biomimetic studies by Hine, in 2007 we developed the bioinspired chiral primary amine catalysts featuring primary-tertiary diamines. This type of catalyst involves enamine/iminium catalysis, and we could apply this chemistry to all of the major types of ketones and aldehydes. In this Account, we present research from our laboratory that significantly expands aminocatalysis to include α-branched ketones such as β-ketocarbonyls and α-substituted vinyl ketones. Our primary amine catalysis methodology, when used alone or in conjunction with metal catalysts, provides convenient access to both enantiopure α-tertiary and quaternary ketones, structures that are not available via other approaches. Our mechanistic studies showed that acidic additives play the critical role in facilitating catalytic turnover, most likely by shuttling protons during the enamine/iminium tautomerizations. These additives are also critical to induce the desired stereochemistry via ammonium N-H hydrogen bonding. Proton transfer by shuttling is also stereoselective, resulting in enantioselective enamine protonation as observed in the reactions of α-substituted vinyl ketones. In addition, we have carried out density functional theory studies that help to delineate the origins of the stereoselectivity in these reactions.

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“…Simple alkenes have rarely been utilized in asymmetric conjugate addition reactions due to the low nucleophilicity and uncontrolled side reactions . Recently, only the Luo group realized the first example of the asymmetric conjugate addition of para -vinylanilines to enones catalyzed by chiral primary amines (Scheme b) . Despite these impressive advances, development of efficient and highly enantioselective protocols for conjugate addition of unactivated alkenyl nucleophiles is still in great demand.…”

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confidence: 99%

Chiral-at-Metal Rh(III) Complex Catalyzed Asymmetric Conjugate Addition of Unactivated Alkenes with α,β-Unsaturated 2-Acyl Imidazoles

Wan

Kang

2017

Org. Lett.

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A newly prepared chiral-at-metal Rh(III) complex catalyzed highly efficient asymmetric conjugate addition of para-vinylanilines with α,β-unsaturated 2-acyl imidazoles is developed, affording the corresponding adducts in 67-95% yields with 86-95% ee. Remarkably, employing as low as 0.05 mol % of Rh(III) complex as catalyst, a gram-scale reaction still affords the desired product in 81% yield with 92% ee.

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Primary–Tertiary Diamine/Brønsted Acid Catalyzed C–C Coupling between para‐Vinylanilines and Aldehydes

Cited by 16 publications

References 47 publications

Organocatalysis in Inert C–H Bond Functionalization

Organocatalysis in Inert C–H Bond Functionalization

Pushing the Limits of Aminocatalysis: Enantioselective Transformations of α-Branched β-Ketocarbonyls and Vinyl Ketones by Chiral Primary Amines

Chiral-at-Metal Rh(III) Complex Catalyzed Asymmetric Conjugate Addition of Unactivated Alkenes with α,β-Unsaturated 2-Acyl Imidazoles

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