<i>N</i>,<i>N′</i>‐Dioxide/Nickel(II)‐Catalyzed Asymmetric Inverse‐Electron‐Demand Hetero‐Diels–Alder Reaction of β,γ‐Unsaturated α‐Ketoesters with Enecarbamates

Zhou, Yuhang; Zhu, Yin; Lin, Lili; Zheng, Jian‐Feng; Liu, Xiaohua; Feng, Xiaoming

doi:10.1002/chem.201403764

Cited by 35 publications

(10 citation statements)

References 54 publications

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“…Nevertheless, in cycloadditions using mono- or disubstituted acyclic vinyl ethers, vinyl sulfides, 3,4-dihydro-2 H -pyrans, and enecarbamates, the dienophiles showed uniform facial selectivity in the presence of the chiral L -PiMe 3 –Ni(BF 4 ) 2 complex . With β,γ-unsaturated α-keto esters as the dienes via bidentate coordination to the Lewis acid (Figure b), the dienophiles mentioned above were tolerated in [4 + 2] cycloadditions. − Notably, the approach of vinyl ethers and ketenes came from different sides, and their approaches were governed by the chiral pocket created by the L -PiPr 2 –Er(OTf) 3 and L -PiPr 2 –Y(OTf) 3 catalysts, respectively . Additionally, asymmetric reactions between o -quinone methide and azlactone mediated by a chiral L -RaMe 2 t Bu –Sc(OTf) 3 complex gave dihydrocoumarin derivatives, and the binding of two monodentate substrates to the Sc(III) center was suggested to control the stereochemistry.…”

Section: Inverse-electron-demand Hetero-diels–alder Reactionsmentioning

confidence: 99%

Asymmetric Cycloaddition and Cyclization Reactions Catalyzed by Chiral N,N′-Dioxide–Metal Complexes

et al. 2017

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Catalytic asymmetric cycloadditions and cascade cyclizations are a major focus for the enantioselective construction of chiral carbo- and heterocycles. A number of chiral Lewis acids and organocatalysts have been designed for such reactions. The development of broadly applicable catalysts bearing novel chiral backbones to meet the demands of various applications is an ongoing challenge. Approximately 10 years ago, we introduced a group of conformationally flexible C-symmetric N,N'-dioxide amide compounds, which represent a new class of privileged ligands. The coordination of the four oxygens of a chiral N,N'-dioxide around a central metal generates an octahedral tricyclometalated Lewis acid catalyst that can carry out various enantioselective reactions. In this Account, we summarize our recent studies on asymmetric cycloadditions between various dienophiles and dienes, dipoles and dipolarophiles, and cascade cyclizations catalyzed by chiral N,N'-dioxide-metal complexes. In principle, these unique chiral catalysts lower the LUMO energy of electron-deficient 2π components or heterodienes by coordination with the functional groups via various binding modes. With N-Boc-3-alkenyloxindole and alkylidene malonate as the electron-deficient 2π components, N,N'-dioxide-metal complexes provided excellent catalytic activities and asymmetric inductions for a variety of transformations, including [2 + 1], [3 + 2], [4 + 2], and [8 + 2] cycloadditions. Mechanistically, these substrates could be efficiently activated through bidentate coordination. The strategy was also useful for asymmetric cascade cyclizations to form polycyclic adducts. Monodentate or bidentate coordination of other α,β-unsubstituted carbonyl compounds to metal centers enabled both normal Diels-Alder reactions and inverse-electron-demand hetero-Diels-Alder reactions as well as [2 + 2] additions. Furthermore, hetero-Diels-Alder reactions of aldehydes, ketones, and imines are well-tolerated and afford various heterocycles. This includes allowing the concise synthesis of the antimalarial compound KAE609. Asymmetric Michael/cyclization reactions of bidentate α,β-unsaturated pyrazolamides gave efficient access to the chiral drugs (-)-paroxetine and (R)-thiazesim. The formal [3 + 2] cycloadditions of donor-acceptor epoxides and aziridines enantioselectively gave a series of five-membered oxo- and aza-heterocycles. The reaction of cyclopropane diketones showed unprecedented reactivities and provided a new route for the synthesis of dihydropyrrole and benzimidazole derivatives. General models for the catalytic reactions emerged from knowledge of the absolute configurations of the products of several reactions and X-ray crystal structures of the catalysts. In the field of chirality created by the coordination of an N,N'-dioxide to a metal center, the bonding of one or two reactants establishes a perfect reaction template for generation of the target adducts. Representative examples have been used to demonstrate how the substructures of the ligands and other reaction co...

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Section: Inverse-electron-demand Hetero-diels–alder Reactionsmentioning

confidence: 99%

Asymmetric Cycloaddition and Cyclization Reactions Catalyzed by Chiral N,N′-Dioxide–Metal Complexes

et al. 2017

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“…Given that enamides serve as a versatile synthetic building unit and potent pharmacophore, a stereoselective access to N -protected enamine fragments is highly desirable . In this context, we attempted to apply the present conditions for the olefinic C–H amidation (see Table ).…”

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confidence: 99%

A Facile Access to Primary Alkylamines and Anilines via Ir(III)-Catalyzed C–H Amidation Using Azidoformates

Kim

Park

et al. 2016

ACS Catal.

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Described herein is the development of Ir(III)-catalyzed direct C–H amidation using azidoformates as a readily deprotectable amino source. Substrates with unactivated methyl C(sp3)–H and aromatic or olefinic C(sp2)–H bonds were smoothly reacted by the iridium-based catalyst system to provide the corresponding primary alkylamines and anilines upon the subsequent removal of N-protecting groups, such as Boc, Fmoc, Cbz, pNZ, or Troc. A brief mechanistic study and synthetic applications are also presented.

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“…Catalyzed by N,N ′‐dioxide 26 /Ni(II) complex, 3,4‐dihydro‐2 H ‐pyranamines 25 were obtained in excellent yields (up to 99 % yield), high diastereoselectivities (>95:5 d.r. ), and excellent ee values (up to 99 % ee) (Scheme ) . The tetradentate N,N ′‐dioxide and the bidentate β,γ ‐unsaturated α ‐ketoester coordinated with nickel to form an octahedral geometry nickel complex, in which the Si face of β,γ ‐unsaturated α ‐ketoester was shielded by the neighboring bulky amide moiety of the ligand.…”

Section: Catalytic Asymmetric Iedhda Reactions Of Carbonyl Compoundsmentioning

confidence: 99%

Catalytic Asymmetric Inverse‐Electron‐Demand Hetero‐Diels−Alder Reactions

Xie

Lin

Feng

2017

The Chemical Record

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In this review, the recent developments in catalytic asymmetric inverse-electron-demand hetero-Diels-Alder reaction, which is recognized as one of the most powerful routes to construct highly functionalized and enantioenriched six-membered heterocycles, are described. The article is organized on the basis of different kinds of electron-deficient heterodienes, including α,β-unsaturated ketones/aldehydes, o-benzoquinones, α,β-unsaturated imines, N-aryl imines, o-benzoqinone imides, and other aza-olefins.

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N,N′‐Dioxide/Nickel(II)‐Catalyzed Asymmetric Inverse‐Electron‐Demand Hetero‐Diels–Alder Reaction of β,γ‐Unsaturated α‐Ketoesters with Enecarbamates

Cited by 35 publications

References 54 publications

Asymmetric Cycloaddition and Cyclization Reactions Catalyzed by Chiral N,N′-Dioxide–Metal Complexes

Asymmetric Cycloaddition and Cyclization Reactions Catalyzed by Chiral N,N′-Dioxide–Metal Complexes

A Facile Access to Primary Alkylamines and Anilines via Ir(III)-Catalyzed C–H Amidation Using Azidoformates

Catalytic Asymmetric Inverse‐Electron‐Demand Hetero‐Diels−Alder Reactions

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