Allylic Alkylation

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 5574 Experts worldwide ranked by ideXlab platform

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

  • Iridium/N-Heterocyclic Carbene Complex-Catalyzed Intermolecular Allylic Alkylation Reaction
    Organometallics, 2018
    Co-Authors: Can-can Bao, Dong-song Zheng, Xiao Zhang, Shu-li You
    Abstract:

    N-Heterocyclic carbenes (NHCs) were found to be suitable ligands in Ir-catalyzed intermolecular Allylic Alkylation reaction. In the presence of a catalyst derived from [Ir(dncot)Cl]2 (dncot = dinaphthocyclooctatetraene) and triazolium salt L7, the Alkylation products from the reaction of aryl allyl carbonates with sodium dialkyl malonates could be obtained in 85–99% yields favoring the formation of branched products (90/10 → >99/1 b/l). In addition, chiral dihydroisoquinoline-type NHC (DHIQ-NHC) (L8) is successfully applied in Ir-catalyzed asymmetric Allylic Alkylation reactions. Excellent enantioselectivities and moderate regioselectivities were obtained for a wide range of substrates.

  • diversity oriented synthesis of indole based peri annulated compounds via Allylic Alkylation reactions
    Chemical Science, 2013
    Co-Authors: Li-xin Dai, Shu-li You
    Abstract:

    Diverse indole-based peri-annulated compounds were synthesized via transition-metal-catalyzed Allylic Alkylation reaction. With palladium catalyst, indole-based nine-membered ring products were obtained in 40–70% yields. When iridium catalyst was used, highly enantioenriched seven-membered ring products were obtained in 40–78% yields and 91–97% ee. Meanwhile, when 3-substituted indole substrates were employed with a palladium catalyst, asymmetric Allylic dearomatization of indoles occurred with products obtained in 48–78% yields and 35–78% ee with a chiral ferrocene-based Phox ligand. Interestingly, with an iridium catalyst, Friedel–Crafts type Allylic Alkylation reaction proceeded at the C5 position of indole, affording the products with 40–60% yields and 56–97% ee.

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.

  • palladium catalyzed enantioselective decarboxylative Allylic Alkylation of cyclopentanones
    Organic Letters, 2015
    Co-Authors: Robert A Craig, Douglas C. Behenna, Steven A Loskot, Justin T Mohr, Andrew M Harned, Brian M. Stoltz
    Abstract:

    The first general method for the enantioselective construction of all-carbon quaternary centers on cyclopentanones by enantioselective palladium-catalyzed decarboxylative Allylic Alkylation is described. Employing the electronically modified (S)-(p-CF3)3-t-BuPHOX ligand, α-quaternary cyclopentanones were isolated in yields up to >99% with ee’s up to 94%. Additionally, in order to facilitate large-scale application of this method, a low catalyst loading protocol was employed, using as little as 0.15 mol % Pd, furnishing the product without any loss in ee.

  • enantioselective synthesis of α quaternary mannich adducts by palladium catalyzed Allylic Alkylation total synthesis of sibirinine
    Journal of the American Chemical Society, 2015
    Co-Authors: Yoshitaka Numajiri, Beau P Pritchett, Koji Chiyoda, Brian M. Stoltz
    Abstract:

    A catalytic enantioselective method for the synthesis of α-quaternary Mannich-type products is reported. The two-step sequence of (1) Mannich reaction followed by (2) decarboxylative enantioselective Allylic Alkylation serves as a novel strategy to in effect access asymmetric Mannich-type products of “thermodynamic” enolates of substrates possessing additional enolizable positions and acidic protons. Palladium-catalyzed decarboxylative Allylic Alkylation enables the enantioselective synthesis of five-, six-, and seven-membered ketone, lactam, and other heterocyclic systems. The mild reaction conditions are notable given the acidic free N–H groups and high functional group tolerance in each of the substrates. The utility of this method is highlighted in the first total synthesis of (+)-sibirinine.

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

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

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