Double Chiral Induction Enables a Stereoselective Carbonyl Allylation with Simple Alkenes under the Sequential Catalysis of Palladium Complex and Chiral Phosphoric Acid

Li, Lulu; Tao, Zhong‐Lin; Han, Zhi‐Yong; Gong, Liu‐Zhu

doi:10.1021/acs.orglett.6b03378

Cited by 52 publications

(15 citation statements)

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“…The Gong group has also been active in the same area as Murakami and Miura: transition-metal-catalyzed allylboronate formation followed by the sequential allylboration of aldehydes. 64,65 In 2015 the group published their first example, in which they use a palladium catalyst to activate an allylic C-H bond to form an allylboronate 2, which in the presence of an aldehyde reacts to form the corresponding anti-homoallylic alcohol 5. 64 The proposed reaction mechanism involves a phosphoric acid binding to the palladium center, and this is thought to be the species responsible for C-H activation; the phosphate can abstract the allylic hydrogen to regenerate the phosphoric acid, leaving the allyl anion coordinated to the palladium (Scheme 36).…”

Section: Review Syn Thesismentioning

confidence: 99%

“…In 2017 the Gong group published another report focusing on the same reaction sequence, but using a double chiral induction strategy; the use of chiral boronates 87 as well as a chiral catalyst 7 (Scheme 37). 65 This time the enantioselectivities were much higher, with many examples of products with over 90% ee. Interestingly, unlike previous reports in which 2,4,6-triisopropylphenyl-substituted TRIP 7a has always provided the best enantioselectivity, the group reports the best results with the 9-anthryl-substitut-…”

Section: Review Syn Thesismentioning

confidence: 99%

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Recent Developments and Applications of the Chiral Brønsted Acid Catalyzed Allylboration of Carbonyl Compounds

et al. 2018

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The 50-year-old allylboration reaction has seen dramatic developments since the dawn of the new century after the first catalytic asymmetric versions came into play. In the past decade alone, several methodologies capable of achieving the desired homoallylic alcohols in over 90% ee have been developed. This review focuses on the chiral Brønsted acid catalyzed allylboration reaction, covering everything from the very first examples and precedents to modern day variations and applications.1 Introduction2 Early Developments3 Synthetic Applications4 Variants5 Computational Contribution6 Conclusions

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Section: Review Syn Thesismentioning

confidence: 99%

Section: Review Syn Thesismentioning

confidence: 99%

Recent Developments and Applications of the Chiral Brønsted Acid Catalyzed Allylboration of Carbonyl Compounds

et al. 2018

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“…Over the past decades, continuous endeavors have been devoted to this field and revealed that sulfoxides, nitrogen ligands, N-heterocyclic carbenes, binaphthols, and some trivalent phosphorus ligands are capable of accelerating Pd-catalyzed allylic C–H functionalization, culminating in the rise of a diverse range of transformations, including oxidations, , aminations, alkylations, fluorination, dehydrogenation, olefination, and even the related enantioselective version . A ground-breaking example of asymmetric allylic C–H activation was reported by Covell and White in 2008, who described the enantioselective allylic C–H acetoxylation of α-alkenes by using a chiral chromium Lewis acid bound with BQ to induce stereoselectivity during nucleophilic attack (Scheme ); however, branched allylic acetate products were obtained with only moderate levels of enantioselectivity.…”

Section: Introductionmentioning

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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“…Amongst them, oxidative borylation seemed to be the most promising strategy with moderate condition and low cost (Scheme 11 ). Hydroxyalkyl derivatives of different configurations can be obtained by employing different diborides and chiral phosphoric acids as ligands [ 102 , 103 ]. Allyl-benzene fragments can also be diastereoselectively hydroxyalkylated catalyzed by ruthenium and iridium catalysts through a cross-metathesis/ isomerization/allylboration sequence [ 104 ].…”

Section: Structural Derivatization Strategies Of Natural Phenols By S...mentioning

confidence: 99%

Structural derivatization strategies of natural phenols by semi-synthesis and total-synthesis

Ding

Jiang

Zhang

et al. 2022

Nat. Prod. Bioprospect.

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Structural derivatization of natural products has been a continuing and irreplaceable source of novel drug leads. Natural phenols are a broad category of natural products with wide pharmacological activity and have offered plenty of clinical drugs. However, the structural complexity and wide variety of natural phenols leads to the difficulty of structural derivatization. Skeleton analysis indicated most types of natural phenols can be structured by the combination and extension of three common fragments containing phenol, phenylpropanoid and benzoyl. Based on these fragments, the derivatization strategies of natural phenols were unified and comprehensively analyzed in this review. In addition to classical methods, advanced strategies with high selectivity, efficiency and practicality were emphasized. Total synthesis strategies of typical fragments such as stilbenes, chalcones and flavonoids were also covered and analyzed as the supplementary for supporting the diversity-oriented derivatization of natural phenols.

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Double Chiral Induction Enables a Stereoselective Carbonyl Allylation with Simple Alkenes under the Sequential Catalysis of Palladium Complex and Chiral Phosphoric Acid

Cited by 52 publications

References 63 publications

Recent Developments and Applications of the Chiral Brønsted Acid Catalyzed Allylboration of Carbonyl Compounds

Recent Developments and Applications of the Chiral Brønsted Acid Catalyzed Allylboration of Carbonyl Compounds

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

Structural derivatization strategies of natural phenols by semi-synthesis and total-synthesis

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