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Shu-li You - One of the best experts on this subject based on the ideXlab platform.
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sequence dependent stereodivergent Allylic Alkylation fluorination of acyclic ketones
Angewandte Chemie, 2020Co-Authors: Xi-jia Liu, Shicheng Jin, Wen-yun Zhang, Chao Zheng, Qiangqiang Liu, Shu-li YouAbstract: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.
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Sequence-Dependent Stereodivergent Allylic Alkylation/Fluorination of Acyclic Ketones.
Angewandte Chemie (International ed. in English), 2019Co-Authors: Xi-jia Liu, Shicheng Jin, Wen-yun Zhang, Qiang‐qiang Liu, Chao Zheng, Shu-li YouAbstract: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.
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Tandem Pd-Catalyzed Intermolecular Allylic Alkylation/Allylic Dearomatization Reaction of Benzoylmethyl pyridines, Pyrazines, and Quinolines
2019Co-Authors: Hui-jun Zhang, Ze-peng Yang, Shu-li YouAbstract: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
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Iridium/N-Heterocyclic Carbene Complex-Catalyzed Intermolecular Allylic Alkylation Reaction
Organometallics, 2018Co-Authors: Can-can Bao, Dong-song Zheng, Xiao Zhang, Shu-li YouAbstract: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.
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diversity oriented synthesis of indole based peri annulated compounds via Allylic Alkylation reactions
Chemical Science, 2013Co-Authors: Li-xin Dai, Shu-li YouAbstract: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.
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Intermolecular Stereoselective Iridium-Catalyzed Allylic Alkylation: An Evolutionary Account
Synlett : accounts and rapid communications in synthetic organic chemistry, 2018Co-Authors: Samantha Elizabeth Shockley, J. Caleb Hethcox, Brian M. StoltzAbstract: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
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Recent developments in stereoselective iridium-catalyzed Allylic Alkylation methodologies
2017Co-Authors: Samantha Elizabeth Shockley, Caleb Hethcox, Brian M. StoltzAbstract: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.
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iridium catalyzed diastereo enantio and regioselective Allylic Alkylation with prochiral enolates
ACS Catalysis, 2016Co-Authors: Caleb J Hethcox, Samantha E Shockley, Brian M. StoltzAbstract: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.
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palladium catalyzed enantioselective decarboxylative Allylic Alkylation of cyclopentanones
Organic Letters, 2015Co-Authors: Robert A Craig, Douglas C. Behenna, Steven A Loskot, Justin T Mohr, Andrew M Harned, Brian M. StoltzAbstract: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.
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enantioselective synthesis of α quaternary mannich adducts by palladium catalyzed Allylic Alkylation total synthesis of sibirinine
Journal of the American Chemical Society, 2015Co-Authors: Yoshitaka Numajiri, Beau P Pritchett, Koji Chiyoda, Brian M. StoltzAbstract: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.
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Ruthenium-Catalyzed Asymmetric Allylic Alkylation of Isatins.
Organic letters, 2020Co-Authors: Barry M Trost, Christopher A Kalnmals, Divya Ramakrishnan, Michael C. Ryan, Rebecca W. Smaha, Sean ParkinAbstract: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 ...
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A borane-mediated palladium-catalyzed reductive Allylic Alkylation of α,β-unsaturated carbonyl compounds
Chemical Science, 2020Co-Authors: Barry M Trost, Zhijun Zuo, Johnathan E. Schultz, Nagaraju Anugula, Katherine A. CarrAbstract: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.
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annulative Allylic Alkylation reactions between dual electrophiles and dual nucleophiles applications in complex molecule synthesis
Chemistry: A European Journal, 2020Co-Authors: Barry M Trost, Christopher A KalnmalsAbstract: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.
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Palladium-Catalyzed Decarboxylative Asymmetric Allylic Alkylation of Dihydroquinolinones
2019Co-Authors: Barry M Trost, Zhijun Zuo, Anugula Nagaraju, Feijun Wang, Kami L. HullAbstract:A palladium-catalyzed decarboxylative asymmetric Allylic Alkylation (Pd-DAAA) of benzo-fused and non-benzo-fused δ-valerolactams is disclosed. This methodology gives access to chiral lactams bearing C3-quaternary stereocenters, which are central to many natural products and biologically active compounds. The reaction proceeds via palladium-catalyzed ionization of an allyl ester, followed by carbon dioxide extrusion and recombination of the electrophilic Pd-π-allyl complex with the in situ generated lactam enolate. This final step converts racemic Allylic ester starting materials into enantiomerically enriched substituted lactams with high yield and enantiomeric excess
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palladium catalyzed asymmetric Allylic Alkylation of electron deficient pyrroles with meso electrophiles
Organic Letters, 2012Co-Authors: Barry M Trost, Maksim Osipov, Guangbin DongAbstract:Pyrroles can serve as competent nucleophiles with meso electrophiles in the Pd-catalyzed asymmetric Allylic Alkylation. The products from this transformation were obtained as a single regio- and diastereomer in high yield and enantiopurity. A nitropyrrole-containing nucleoside analogue was synthesized in seven steps to demonstrate the synthetic utility of this transformation.
Santanu Mukherjee - One of the best experts on this subject based on the ideXlab platform.
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Iridium-catalyzed enantioselective olefinic C(sp2)–H Allylic Alkylation
Chemical Science, 2021Co-Authors: Rahul Sarkar, Santanu MukherjeeAbstract: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 catalysis.
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Iridium-Catalyzed Enantioselective α-Allylic Alkylation of Amides Using Vinyl Azide as Amide Enolate Surrogate.
Organic letters, 2020Co-Authors: Aditya Chakrabarty, Santanu MukherjeeAbstract: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.
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Iridium-Catalyzed Asymmetric α-Allylic Alkylation of Amides using Vinyl Azide as Amide Enolate Surrogate
2020Co-Authors: Aditya Chakrabarty, Santanu MukherjeeAbstract: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>
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Catalytic Enantioselective Vinylogous Allylic Alkylation of Coumarins.
Organic letters, 2017Co-Authors: Satavisha Kayal, Santanu MukherjeeAbstract:An unprecedented, organocatalytic enantioselective vinylogous γ-Allylic Alkylation of 4-methylcoumarins has been developed. Using Allylic carbonates as the allyl source, this reaction is catalyzed by Lewis basic dimeric Cinchona alkaloid (QD)2PHAL and proceeds exclusively in a γ- and branched-selective manner to produce densely functionalized coumarin derivatives generally in good yields with good to high enantioselectivities (up to 97:3 er).
Alexandre Alexakis - One of the best experts on this subject based on the ideXlab platform.
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Construction of Enantioenriched Cyclic Compounds by Asymmetric Allylic Alkylation and Ring-Closing Metathesis.
ChemInform, 2014Co-Authors: Francesca Giacomina, Alexandre AlexakisAbstract: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.
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Copper-Free Asymmetric Allylic Alkylation with Grignard Reagents.
ChemInform, 2010Co-Authors: Olivier Jackowski, Alexandre AlexakisAbstract:The copper-free asymmetric Allylic Alkylation reaction of different Grignard reagents (II) with various allyl bromides is catalyzed by an N-heterocyclic carbene.
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Copper‐Free Asymmetric Allylic Alkylation with Grignard Reagents
Angewandte Chemie (International ed. in English), 2010Co-Authors: Olivier Jackowski, Alexandre AlexakisAbstract: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).
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Dynamic kinetic asymmetric transformation in copper catalyzed Allylic Alkylation
Chemical communications (Cambridge England), 2009Co-Authors: Jean-baptiste Langlois, Alexandre AlexakisAbstract:The first dynamic kinetic asymmetric transformation in copper catalyzed Allylic Alkylation is reported, with enantioselectivities up to 92%.
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copper catalyzed asymmetric Allylic Alkylation
European Journal of Organic Chemistry, 2008Co-Authors: Caroline A. Falciola, Alexandre AlexakisAbstract:Over the past decade, much effort has been put on designing efficient chiral ligands and screening of the different parameters that govern the main challenges of asymmetric SN2′ reactions, namely chemo-, regio- and enantioselectivity. This review traces the evolution of the methodologies for creating stereogenic centers through asymmetric copper-catalyzed Allylic Alkylation with the use of different organometallic reagents and their subsequent applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)