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Allylic Alkylation

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Shu-li You – One of the best experts on this subject based on the ideXlab platform.

  • sequence dependent stereodivergent Allylic Alkylation fluorination of acyclic ketones
    Angewandte Chemie, 2020
    Co-Authors: Xi-jia Liu, Shicheng Jin, Wen-yun Zhang, Chao Zheng, Qiangqiang Liu, Shu-li You
    Abstract:

    The stereodivergent iridium-catalyzed Allylic Alkylation and fluorination of acyclic ketones is described. α-Pyridyl-α-fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities. Distinct from known stereodivergent synthesis, for which two different chiral catalysts are required in general, herein we report a sequence-dependent stereodivergent synthesis. With only a single chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric Allylic Alkylation and fluorination and varying the absolute configuration of the Ir catalyst.

  • Sequence-Dependent Stereodivergent Allylic Alkylation/Fluorination of Acyclic Ketones.
    Angewandte Chemie (International ed. in English), 2019
    Co-Authors: Xi-jia Liu, Shicheng Jin, Wen-yun Zhang, Qiang‐qiang Liu, Chao Zheng, Shu-li You
    Abstract:

    The stereodivergent iridium-catalyzed Allylic Alkylation and fluorination of acyclic ketones is described. α-Pyridyl-α-fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities. Distinct from known stereodivergent synthesis, for which two different chiral catalysts are required in general, herein we report a sequence-dependent stereodivergent synthesis. With only a single chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric Allylic Alkylation and fluorination and varying the absolute configuration of the Ir catalyst.

  • Tandem Pd-Catalyzed Intermolecular Allylic Alkylation/Allylic Dearomatization Reaction of Benzoylmethyl pyridines, Pyrazines, and Quinolines
    , 2019
    Co-Authors: Hui-jun Zhang, Ze-peng Yang, Shu-li You
    Abstract:

    An efficient synthesis of nitrogen-containing heterocycles via Pd-catalyzed tandem Allylic Alkylation and dearomatization reactions was reported. In this reaction design, heteroarenes such as pyridines, pyrazines, and quinolines serve as bis-nucleophiles by installing a benzoyl group at the C2 benzylic position. With but-2-ene-1,4-diyl dimethyl dicarbonate as the bis-electrophile, the tandem Pd-catalyzed intermolecular Allylic Alkylation/Allylic dearomatization reaction of benzoylmethyl-substituted heteroarenes has been developed. 2,3-Dihydroindolizine, 6,7-dihydropyrrolo­[1,2-a]­pyrazine, and 1,2-dihydropyrrolo­[1,2-a]­quinolin derivatives were obtained in moderate to good yields

Brian M. Stoltz – One of the best experts on this subject based on the ideXlab platform.

  • Intermolecular Stereoselective Iridium-Catalyzed Allylic Alkylation: An Evolutionary Account
    Synlett : accounts and rapid communications in synthetic organic chemistry, 2018
    Co-Authors: Samantha Elizabeth Shockley, J. Caleb Hethcox, Brian M. Stoltz
    Abstract:

    Our lab has long been interested in the development of methods for the creation of enantioenriched all-carbon quaternary stereocenters. Historically, our interest has centered on palladium-catalyzed Allylic Alkylation, though recent efforts have moved to include the study of iridium catalysts. Whereas palladium catalysts enable the preparation of isolated stereocenters, the use of iridium catalysts allows for the direct construction of vicinal stereocenters via an enantio-, diastereo-, and regioselective Allylic Alkylation. This Account details the evolution of our research program from inception, which focused on the first iridium-catalyzed Allylic Alkylation to prepare stereodyads containing a single quaternary stereocenter, to our most recent discovery that allows for the synthesis of vicinal quaternary centers. 1 Introduction 2 Synthesis of Vicinal Tertiary and All-Carbon Quaternary Stereocenters via Enantio- and Diastereoselective Iridium-Catalyzed Allylic Alkylation 2.1 Cyclic Nucleophiles 2.2 Acyclic Nucleophiles 2.3 Alkyl-Substituted Electrophiles 3 Umpoled Iridium-Catalyzed Allylic Alkylation Reactions 3.1 Tertiary Allylic Stereocenters 3.2 Quaternary Allylic Stereocenters 4 Synthesis of Vicinal All-Carbon Quaternary Centers via Enantio­selective Iridium-Catalyzed Allylic Alkylation 5 Summary and Future Outlook

  • Recent developments in stereoselective iridium-catalyzed Allylic Alkylation methodologies
    , 2017
    Co-Authors: Samantha Elizabeth Shockley, Caleb Hethcox, Brian M. Stoltz
    Abstract:

    We report our ongoing studies in the field of iridium-catalyzed Allylic Alkylation chem. The first regio-, diastereo-, and enantioselective transition-metal-catalyzed Allylic Alkylation reaction forming vicinal tertiary and all-carbon quaternary stereocenters between prochiral enolates and an aliph.-substituted electrophile is disclosed. Crit. to the success of this new reaction is the identity and ubiquity of the chloride counterion in addn. to the use of proton sponge, the combination of which affords excellent regio- and enantioselectivities along with good yields and diastereoselectivities. Addnl., a no. of transformations were carried out on the Alkylation products to demonstrate the value of this method in rapidly accessing highly functionalized, stereochem. rich polycyclic scaffolds. Further exploration of this chem. has continued to expand the scope of these types of transformations with respect to the nucleophile and electrophile. Our recent efforts in this field will be discussed.

  • iridium catalyzed diastereo enantio and regioselective Allylic Alkylation with prochiral enolates
    ACS Catalysis, 2016
    Co-Authors: Caleb J Hethcox, Samantha E Shockley, Brian M. Stoltz
    Abstract:

    Transition-metal-catalyzed asymmetric Allylic Alkylation of enolates is a powerful method for the formation of carbon− carbon bonds. Within this field, palladium-catalyzed Allylic Alkylation reactions have undoubtedly been the most studied. Aside from limited cases, palladium catalysts preferentially form the linear substitution product through Alkylation at the less-substituted terminus of the Allylic electrophile (Scheme 1). However, in contrast to palladium, most other transition metals (e.g., Mo, W, Fe, Ru, Co, Rh, Ni, Pt, and Ir) have been shown to favor the construction of the branched product, with iridium catalysts being some of the most efficient and selective. The potential application of these chiral, branched products to the synthesis of natural products and biologically active compounds has motivated the development of practical and reliable transition-metal-catalyzed methods for their construction.

Barry M Trost – One of the best experts on this subject based on the ideXlab platform.

  • Ruthenium-Catalyzed Asymmetric Allylic Alkylation of Isatins.
    Organic letters, 2020
    Co-Authors: Barry M Trost, Christopher A Kalnmals, Divya Ramakrishnan, Michael C. Ryan, Rebecca W. Smaha, Sean Parkin
    Abstract:

    A new ruthenium-based catalytic system for branched-selective asymmetric Allylic Alkylation is disclosed and applied to the synthesis of chiral isatin derivatives. The catalyst, which is generated …

  • A borane-mediated palladium-catalyzed reductive Allylic Alkylation of α,β-unsaturated carbonyl compounds
    Chemical Science, 2020
    Co-Authors: Barry M Trost, Zhijun Zuo, Johnathan E. Schultz, Nagaraju Anugula, Katherine A. Carr
    Abstract:

    The development of the palladium-catalyzed Allylic Alkylation of in situ generated boron enolates via tandem 1,4-hydroboration is reported. Investigation of the reaction revealed insights into specific catalyst electronic features as well as a profound leaving group effect that proved crucial for achieving efficient Allylic Alkylation of ester enolates at room temperature and ultimately a highly preparatively useful synthesis of notoriously challenging acyclic all-carbon quaternary stereocenters. The method demonstrates boron enolates as viable pro-nucleophiles in transition-metal catalyzed Allylic Alkylation, potentially opening up further transformations outside their traditional use.

  • annulative Allylic Alkylation reactions between dual electrophiles and dual nucleophiles applications in complex molecule synthesis
    Chemistry: A European Journal, 2020
    Co-Authors: Barry M Trost, Christopher A Kalnmals
    Abstract:

    Metal-catalyzed Allylic Alkylation reactions between dual nucleophiles and dual electrophiles represent a powerful set of methods for the synthesis of small-, medium-, and even large-sized rings. Using this strategy, a handful of simple Allylic diol derivatives can be transformed into a broad array of complex carbo- and heterocycles of varying ring sizes in just a single step. Because of their ability to rapidly generate complexity, annulative Allylic Alkylation reactions between dual nucleophiles and dual electrophiles have been extensively employed in the total synthesis of both natural products and pharmaceutical compounds.

Santanu Mukherjee – One of the best experts on this subject based on the ideXlab platform.

  • Iridium-catalyzed enantioselective olefinic C(sp2)–H Allylic Alkylation
    Chemical Science, 2021
    Co-Authors: Rahul Sarkar, Santanu Mukherjee
    Abstract:

    The first iridium-catalyzed enantioselective Allylic Alkylation of an olefinic C(sp2)–H bond – that of an α,β-unsaturated carbonyl compound, is developed in cooperation with Lewis base catacatalysis.

  • Iridium-Catalyzed Enantioselective α-Allylic Alkylation of Amides Using Vinyl Azide as Amide Enolate Surrogate.
    Organic letters, 2020
    Co-Authors: Aditya Chakrabarty, Santanu Mukherjee
    Abstract:

    Among the unstabilized enolates used as nucleophiles in iridium-catalyzed asymmetric Allylic Alkylation reactions, amide enolates are the least explored. Vinyl azides are now employed as amide enolate surrogates in Ir-catalyzed asymmetric Allylic Alkylation with branched Allylic alcohols as the Allylic electrophile. Competing reaction pathways are suppressed through the systematic tuning of the steric and electronic properties of vinyl azide to effect the α-Allylic Alkylation of secondary acetamides with high atom economy, exclusive branched selectivity, and mostly excellent enantioselectivity.

  • Iridium-Catalyzed Asymmetric α-Allylic Alkylation of Amides using Vinyl Azide as Amide Enolate Surrogate
    , 2020
    Co-Authors: Aditya Chakrabarty, Santanu Mukherjee
    Abstract:

    Among the unstabilized enolates used as nucleophile in iridium-catalyzed asymmetric Allylic Alkylation reactions, amide enolates are least explored. Vinyl azides are now employed as amide enolate surrogate for the first time in Ir-catalyzed asymmetric Allylic Alkylation with branched Allylic alcohols as the Allylic electrophile. Competing reaction pathways are suppressed through systematic tuning of steric and electronic properties of vinyl azide to effect α-Allylic Alkylation of secondary acetamides with high atom-economy, exclusive branched selectivity and moderate to excellent enantioselectivity.<br>

Alexandre Alexakis – One of the best experts on this subject based on the ideXlab platform.

  • Construction of Enantioenriched Cyclic Compounds by Asymmetric Allylic Alkylation and Ring-Closing Metathesis.
    ChemInform, 2014
    Co-Authors: Francesca Giacomina, Alexandre Alexakis
    Abstract:

    In some cases the two step procedure is performed in one pot without quenching the reaction mixture after the Allylic Alkylation step before the Grubbs catalyst is added.

  • Copper-Free Asymmetric Allylic Alkylation with Grignard Reagents.
    ChemInform, 2010
    Co-Authors: Olivier Jackowski, Alexandre Alexakis
    Abstract:

    The copper-free asymmetric Allylic Alkylation reaction of different Grignard reagents (II) with various allyl bromides is catalyzed by an N-heterocyclic carbene.

  • Copper‐Free Asymmetric Allylic Alkylation with Grignard Reagents
    Angewandte Chemie (International ed. in English), 2010
    Co-Authors: Olivier Jackowski, Alexandre Alexakis
    Abstract:

    Open wide and say AAA: The copper-free asymmetric Allylic Alkylation reaction of Grignard reagents, catalyzed by N-heterocyclic carbenes, is reported for allyl bromide derivatives. This reaction offers good enantioselectivity and good to excellent γ regioselectivity, particularly for the formation of quaternary chiral centers (see scheme; Mes=mesityl).