Journal ArticleDOI
Palladium-Catalyzed Asymmetric Allylic C-H Functionalization: Mechanism, Stereo- and Regioselectivities, and Synthetic Applications.
Pu-Sheng Wang,Liu-Zhu Gong +1 more
TLDR
This Account focuses on describing the origin, evolution, and synthetic applications of Pd-catalyzed asymmetric allylic C-H functionalization reactions, with an emphasis on the fundamental mechanism of the concerted proton and two-electron transfer process in allylicC-H activation.Abstract:
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 Pd-catalyzed 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 Pd-catalyzed 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 bond-forming 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,α-disubstituted 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.read more
Citations
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Journal ArticleDOI
Organo/Transition-Metal Combined Catalysis Rejuvenates Both in Asymmetric Synthesis.
Dianpeng Chen,Liu-Zhu Gong +1 more
TL;DR: Readers are provided with the fundamental attributes of AOMCorthogonality, kinetics, mechanism, and selectivity to understand how an organocatalyst and a transition-metal complex would collaborate to enable fruitful new reaction development and what are the intrinsic pathways of unproductive events, such as catalyst self-quenching.
Journal ArticleDOI
Forging C−heteroatom bonds by transition-metal-catalyzed enantioselective C–H functionalization
TL;DR: In this article , the authors summarized the advances in C-X bond-forming asymmetric C-H activation reactions proceeding through C−H metalation, organized based on the utilized catalytic systems, including Pd(II) and group-9 CpxM(III) catalysis, with emphasis on the design philosophy, mechanism, and mode of enantiocontrol.
Journal ArticleDOI
Cp*Co(III)-Catalyzed Enantioselective Hydroarylation of Unactivated Terminal Alkenes via C-H Activation.
Yan-Hua Liu,Pei-Pei Xie,Lei Liu,Jun Fan,Zhuo-Zhuo Zhang,Xin Hong,Bing-Feng Shi,Bing-Feng Shi +7 more
TL;DR: In this paper, a Cp*Co(III)-catalyzed asymmetric hydroarylation of unactivated aliphatic terminal alkenes assisted by a new type of tailor-made amino acid ligands was reported.
Journal ArticleDOI
Synthesis of Chiral Spirolactams via Sequential C−H Olefination/Asymmetric [4+1] Spirocyclization under a Simple Co(II)/Chiral Spiro Phosphoric Acid Binary System
Wen-Kui Yuan,Bing-Feng Shi +1 more
TL;DR: An unprecedented enantioselective synthesis of spiro-γ-lactams via a sequential C-H olefination/asymmetric [4+1] spirocyclization under a simple Co(II)/chiral spiro phosphoric acid (SPA) binary system is reported.
References
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Journal ArticleDOI
Asymmetric transition-metal-catalyzed allylic alkylations: applications in total synthesis.
TL;DR: Alkylations with Phenols, Nitrogen Nucleophiles in AAA Total Synthesis, and Considerations for Enantioselective Allylic Alkylation are presented.
Journal ArticleDOI
Recent advances in olefin metathesis and its application in organic synthesis
Robert H. Grubbs,Sukbok Chang +1 more
TL;DR: In this paper, a review of recent advances in olefin metathesis focusing on the areas of ring-closing olefi cation (RCM) and cross-metathesis is presented.
Journal ArticleDOI
The asymmetric intramolecular Heck reaction in natural product total synthesis.
Amy B. Dounay,Larry E. Overman +1 more
Journal ArticleDOI
Metal-catalyzed enantioselective allylation in asymmetric synthesis.
TL;DR: Metal-catalyzed enantioselective allylation, which involves the substitution of allylic metal intermediates with a diverse range of different nucleophiles or S(N)2'-type allylic substitution, leads to the formation of C-H, -C, -O, -N, -S, and other bonds with very high levels of asymmetric induction.
Journal ArticleDOI
Metal-Catalyzed Epoxidations of Alkenes with Hydrogen Peroxide
Benjamin S. Lane,Kevin Burgess +1 more
TL;DR: Metal Oxides Generated in Situ 2461 4.1.