Asymmetric Allylic C-H Alkylation of 1,4-Dienes with Aldehydes

周霄乐,; 苏永亮,; 汪普生,; 龚流柱,

doi:10.6023/a18060235

Cited by 21 publications

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“…The asymmetric α-allylation of 2-aryl propionaldehydes with 1,4-dienes enabled by the cooperative catalysis of the Pd(0) complex, A1 , and PA1 also proceeded successfully to yield chiral α-quaternary carbonyl compounds (Scheme ). A palladium complex in situ generated from Pd(dba) 2 and P(4-MeOC 6 H 4 ) 3 turned out to be the most efficient metal catalyst, which functioned in concert with the aforementioned organocatalysts to allow a range of aryl and alkyl substituted 1,4-dienes incorporated with functional groups to deliver excellent levels of regio-, E / Z , and stereoselectivity.…”

Section: Control Of Stereo- and Regioselectionmentioning

confidence: 99%

Palladium-Catalyzed Asymmetric Allylic C–H Functionalization: Mechanism, Stereo- and Regioselectivities, and Synthetic Applications

2020

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Metrics & MoreArticle Recommendations CONSPECTUS: Asymmetric functionalization of inert C−H bonds is undoubtedly a synthetically significant yet challenging bond-forming process, allowing for the preparation of densely functionalized molecules from abundantly available feedstocks. In the past decade, our group and others have found that trivalent phosphorus ligands are capable of facilitating Pdcatalyzed allylic C−H functionalization of α-alkenes upon using p-quinone as an oxidant. In these reactions, a 16-electron Pd(0) complex bearing a monodentate phosphorus ligand, a p-quinone, and an α-alkene has been identified as a key intermediate. Through a concerted proton and two-electron transfer process, electrophilic π-allylpalladium is subsequently generated and can be leveraged to forge versatile chemical bonds with a wide range of nucleophiles. This Account focuses on describing the origin, evolution, and synthetic applications of Pdcatalyzed asymmetric allylic C−H functionalization reactions, with an emphasis on the fundamental mechanism of the concerted proton and two-electron transfer process in allylic C−H activation.Enabled by the cooperative catalysis of the palladium complex of triarylphosphine, a primary amine, and a chiral phosphoric acid, an enantioselective α-allylation of aldehydes with α-alkenes is established. The combination of chiral phosphoric acid and a palladium complex of a chiral phosphoramidite ligand allows the allylic C−H alkylation of α-alkenes with pyrazol-5-ones to give excellent enantioselectivities, wherein the chiral ligand and chiral phosphoric acid synergistically control the stereoselectivity. Notably, the palladium−phosphoramidite complexes are also efficient catalysts for allylic C−H alkylation, with a wide scope of nucleophiles. In the case of 1,4-dienes, the geometry and coordination pattern of the nucleophile are able to vary the transition states of bondforming events and thereby determine the Z/E-, regio-, and stereoselectivities. These enantioselective allylic C−H functionalization reactions are tolerant of a wide range of nucleophiles and α-alkenes, providing a large library of optically active building blocks. Based on enantioselective intramolecular allylic C−H oxidation, the formal synthesis of (+)-diversonol is accomplished, and enantioselective intramolecular allylic C−H amination can enable concise access to letermovir. In particular, the asymmetric allylic C−H alkylation of 1,4-dienes with azlactones offers highly enantioenriched α,αdisubstituted α-amino acid derivatives that are capable of serving as key building blocks for the enantioselective synthesis of lepadiformine alkaloids. In addition, a tachykinin receptor antagonist and (−)-tanikolide are also synthesized with chiral molecules generated from the corresponding allylic C−H alkylation reactions.

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Section: Control Of Stereo- and Regioselectionmentioning

confidence: 99%

Palladium-Catalyzed Asymmetric Allylic C–H Functionalization: Mechanism, Stereo- and Regioselectivities, and Synthetic Applications

2020

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“…Benzyl and substituted benzyl groups bearing either electron-donating or electron-withdrawing substituents at the para-, meta-, or ortho-position (7-15) were well tolerated. It was worth noting that medicinally relevant heterocycles such as furan (16) and thiophene (17) could undergo the allylation efficiently with good results. In addition, long-chain alkyl (18), alkyl ether (19), and allyl groups (20 and 21) were also compatible with the reaction.…”

Section: Pt-catalyzed Allylic C−h Alkylation Of α-Alkenes With Malononitrilesmentioning

confidence: 99%

“…Among the landmark advances with transition-metal catalysis, 5,6 palladium (Pd)-catalyzed allylic C-H functionalization of readily available α-alkenes is distinguished by enabling the access to alkene-bearing structurally complex molecules with versatile bond-forming capacity and minimal manipulation of functional groups, [7][8][9] thereby being regarded as an atom-and step-economic alternative to Tsuji-Trost allylation reactions by avoiding the use of preoxidized allylating reagents. 10,11 In recent decades, our group [12][13][14][15][16][17][18][19][20][21][22][23][24] and others [25][26][27][28] have found that trivalent phosphorus ligands are capable of facilitating Pd-catalyzed allylic C-H cleavage through a concerted proton and two-electron transfer process (Scheme 1), 22 thereby generating electrophilic π-allylpalladium intermediates that can be leveraged to forge chemical bonds with a wide range of nucleophiles. 29 Upon using p-quinone as an oxidant, the 16-electron Pd(0) complex 1 bearing a phosphorus ligand, a quinone, and an α-alkene is most likely to be a key intermediate for allylic C-H activation.…”

Section: Introductionmentioning

confidence: 99%

Platinum-Catalyzed Allylic C–H Alkylation with Malononitriles

et al. 2022

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The direct functionalization of allylic C-H bonds is distinguished by enabling rapid assembly of structural complexity from simple molecules. Although Pd-catalyzed allylic C-H functionalization has been extensively studied, the discovery of new catalytic systems remains fairly underdeveloped. Here, we disclose a Pt-catalyzed allylic C-H alkylation of a wide range of α-alkenes by using phosphoramidites as ligands and malononitriles as alkylating reagents. Notably, the combination of chiral ureacatalyzed Michael addition and Pt-catalyzed allylic C-H alkylation can serve as an efficient protocol to access chiral tetrahydropyran with high levels of diastereo-and enantioselectivity. Mechanistic studies suggest that the Pt-catalyzed allylic C-H activation proceeds through a concerted proton and two-electron transfer process, which is analogous to transition state geometries of Pd catalysis.

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“…The cooperative combination of amine and palladium catalysts of Subchapter 2.1.4 was simultaneously used by Gong's team for AAA H of terminal alkenes [80,81] and 1,4‐dienes [81] . Best results were obtained with cumylamine, chiral Brønsted acid ent ‐BA* 5 and 2,6‐DMBQ in the presence 3Å molecular sieves (Schemes 19a and 19b).…”

Section: Using Pd0 Ln Catalyst and Quinonementioning

confidence: 99%

Allylic C(sp³)−C(sp³) Bond Formation Through Pd‐Catalyzed C(sp³)−H Activation of Alkenes and 1,4‐Dienes

Мuzart

2022

Adv Synth Catal

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This review highlights the allylic CÀ H alkylation of alkenes (AA H ) with nucleophiles under Pd 0 or Pd II catalysis and achiral or chiral conditions. The η 3 -allylpalladium intermediates of these reactions are formed from the cleavage of an allylic hydrogen which becomes a leaving group, like the acetate moiety of allyl acetates during the classical Tsuji-Trost procedure. Most of these cross-dehydrogenative-couplings require quinones as key components; they may play the role of ligand, proton trap and oxidant. Efficient asymmetric allylic CÀ H alkylations (AAA H 's) have been performed. The diversity of the procedures, their limitation and application in synthesis are underlined as well as the proposed mechanisms with, in some cases, personal comments. The data are grouped according to the reaction conditions.1.

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Asymmetric Allylic C-H Alkylation of 1,4-Dienes with Aldehydes

Cited by 21 publications

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Palladium-Catalyzed Asymmetric Allylic C–H Functionalization: Mechanism, Stereo- and Regioselectivities, and Synthetic Applications

Palladium-Catalyzed Asymmetric Allylic C–H Functionalization: Mechanism, Stereo- and Regioselectivities, and Synthetic Applications

Platinum-Catalyzed Allylic C–H Alkylation with Malononitriles

Allylic C(sp³)−C(sp³) Bond Formation Through Pd‐Catalyzed C(sp³)−H Activation of Alkenes and 1,4‐Dienes

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Asymmetric Allylic C-H Alkylation of 1,4-Dienes with Aldehydes

Cited by 21 publications

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Palladium-Catalyzed Asymmetric Allylic C–H Functionalization: Mechanism, Stereo- and Regioselectivities, and Synthetic Applications

Palladium-Catalyzed Asymmetric Allylic C–H Functionalization: Mechanism, Stereo- and Regioselectivities, and Synthetic Applications

Platinum-Catalyzed Allylic C–H Alkylation with Malononitriles

Allylic C(sp3)−C(sp3) Bond Formation Through Pd‐Catalyzed C(sp3)−H Activation of Alkenes and 1,4‐Dienes

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Allylic C(sp³)−C(sp³) Bond Formation Through Pd‐Catalyzed C(sp³)−H Activation of Alkenes and 1,4‐Dienes