Iridium-Catalyzed Asymmetric Allylic Substitution Reactions

Chemical Reviews, Journal Year: 2018, Volume and Issue: 119(3), P. 1855 - 1969

Published: Dec. 24, 2018

In this review, we summarize the origin and advancements of iridium-catalyzed asymmetric allylic substitution reactions during past two decades. Since first report in 1997, Ir-catalyzed have attracted intense attention due to their exceptionally high regio- enantioselectivities. been significantly developed recent years many respects, including ligand development, mechanistic understanding, substrate scope, application synthesis complex functional molecules. an explicit outline ligands, mechanism, scope nucleophiles, applications is presented.

Language: Английский

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Advances in Catalytic Asymmetric Dearomatization

ACS Central Science, Journal Year: 2021, Volume and Issue: 7(3), P. 432 - 444

Published: Feb. 22, 2021

Asymmetric catalysis has been recognized as the most enabling strategy for accessing chiral molecules in enantioenriched forms. Catalytic asymmetric dearomatization is an emerging and dynamic research subject catalysis, which received considerable attention recent years. The direct transformations from readily available aromatic feedstocks to structurally diverse three-dimensional polycyclic make catalytic reactions of broad interest both organic synthesis medicinal chemistry. However, inherent difficulty disruption aromaticity demands a large energy input during process, might be incompatible with conditions generally required by catalysis. In this Outlook, we will discuss representative strategies examples various compounds try convince readers that overcoming above obstacles, could advance chemical sciences many respects.

Language: Английский

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Diastereodivergent synthesis of enantioenriched α,β-disubstituted γ-butyrolactones via cooperative N-heterocyclic carbene and Ir catalysis

Nature Catalysis, Journal Year: 2019, Volume and Issue: 3(1), P. 48 - 54

Published: Dec. 2, 2019

Language: Английский

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Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(3), P. 1122 - 1246

Published: Jan. 2, 2024

Dearomatization reactions have become fundamental chemical transformations in organic synthesis since they allow for the generation of three-dimensional complexity from two-dimensional precursors, bridging arene feedstocks with alicyclic structures. When those processes are applied to pyridines, quinolines, and isoquinolines, partially or fully saturated nitrogen heterocycles formed, which among most significant structural components pharmaceuticals natural products. The inherent challenge lies low reactivity heteroaromatic substrates, makes dearomatization process thermodynamically unfavorable. Usually, connecting event irreversible formation a strong C–C, C–H, C–heteroatom bond compensates energy required disrupt aromaticity. This aromaticity breakup normally results 1,2- 1,4-functionalization heterocycle. Moreover, combination these subsequent tandem stepwise protocols allows multiple heterocycle functionalizations, giving access complex molecular skeletons. aim this review, covers period 2016 2022, is update state art nucleophilic dearomatizations showing extraordinary ability dearomative methodology indicating their limitations future trends.

Language: Английский

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Time-dependent enantiodivergent synthesis via sequential kinetic resolution

Nature Chemistry, Journal Year: 2020, Volume and Issue: 12(9), P. 838 - 844

Published: June 29, 2020

Language: Английский

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Modular Access to Spiro-dihydroquinolines via Scandium-Catalyzed Dearomative Annulation of Quinolines with Alkynes

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(48), P. 20462 - 20471

Published: Nov. 23, 2021

The catalytic enantioselective construction of three-dimensional molecular architectures from planar aromatics such as quinolines is great interest and importance the viewpoint both organic synthesis drug discovery, but there still exist many challenges. Here, we report scandium-catalyzed asymmetric dearomative spiro-annulation with alkynes. This protocol offers an efficient selective route for spiro-dihydroquinoline derivatives containing a quaternary carbon stereocenter unprotected N–H group readily accessible diverse alkynes, featuring high yields, enantioselectivity, 100% atom-efficiency, broad substrate scope. Experimental density functional theory studies revealed that reaction proceeded through C–H activation 2-aryl substituent in quinoline by scandium alkyl (or amido) species followed alkyne insertion into Sc–aryl bond subsequent 1,2-addition resulting alkenyl to C═N unit moiety. work opens new avenue dearomatization quinolines, leading spiro were previously difficult access other means.

Language: Английский

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Enantioselective Dearomative [3 + 2] Umpolung Annulation of N-Heteroarenes with Alkynes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(3), P. 1087 - 1093

Published: Jan. 10, 2022

Enantioselective [3 + 2] annulation of N-heteroarenes with alkynes has been developed via a cobalt-catalyzed dearomative umpolung strategy in the presence chiral ligand and reducing reagent. A variety electron-deficient N-heteroarenes, including quinolines, isoquinolines, quinoxaline, pyridines, internal or terminal are employed this reaction, showing broad substrate scope good functionality tolerance. Annulation electron-rich indoles is also developed. This protocol provides straightforward access to N-spiroheterocyclic molecules excellent enantioselectivities (76 examples, up 99% ee).

Language: Английский

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Tandem Dearomatization/Enantioselective Allylic Alkylation of Pyridines

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(22), P. 11907 - 11913

Published: May 22, 2023

Herein, we report a multistep one-pot reaction of substituted pyridines leading to N-protected tetrahydropyridines with outstanding enantioselectivity (up 97% ee). An iridium(I)-catalyzed dearomative 1,2-hydrosilylation enables the use N-silyl enamines as new type nucleophile in subsequent palladium-catalyzed asymmetric allylic alkylation. This telescoped process overcomes intrinsic nucleophilic selectivity synthesize enantioenriched, C-3-substituted tetrahydropyridine products that have been otherwise challenging access.

Language: Английский

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Highly Diastereo- and Enantioselective Synthesis of Quinuclidine Derivatives by an Iridium-Catalyzed Intramolecular Allylic Dearomatization Reaction

CCS Chemistry, Journal Year: 2019, Volume and Issue: 1(1), P. 106 - 116

Published: April 1, 2019

Open AccessCCS ChemistryRESEARCH ARTICLE1 Apr 2019Highly Diastereo- and Enantioselective Synthesis of Quinuclidine Derivatives by an Iridium-Catalyzed Intramolecular Allylic Dearomatization Reaction Lin Huang, Yue Cai, Hui-Jun Zhang, Chao Zheng, Li-Xin Dai Shu-Li You Huang State Key Laboratory Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute Organic University Chinese Academy Sciences, 200032 (China) , Cai Zhang Zheng *Corresponding author: E-mail Address: [email protected] Collaborative Innovation Chemical Science Engineering, Tianjin https://doi.org/10.31635/ccschem.019.20180006 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Asymmetric construction quinuclidine derivatives has been realized iridium-catalyzed allylic dearomatization reaction. The catalytic system, derived from [Ir(cod)Cl]2 the Feringa ligand, tolerates a broad range substrates. A large array can be obtained under mild conditions good excellent yields (68%–96%), diastereoselectivity (up >20/1 dr), enantioselectivity >99% ee). These products feature versatile functional group diversity undergo diverse transformations. model that accounts origin stereoselectivity proposed based on density theory (DFT) calculations. Download figure PowerPoint Introduction Quinuclidine, also named 1-azabicyclo[2.2.2]octane, exists number naturally occurring compounds, biologically active agents, privileged catalysts ligands asymmetric catalysis (Figure 1).1–6 In particular, quinine, kind cinchona alkaloid, recognized as medication treatment malaria babesiosis.7,8 are widely utilized homogeneous or heterogeneous various processes such Morita–Baylis–Hillman reactions,4 Sharpless dihydroxylation reactions,5 phase-transfer reactions.6 Therefore, development synthetic approaches efficient novel is great significance. Figure 1 | Selected natural molecules containing scaffolds. this regard, efforts have devoted new methods toward preparation derivatives.9 Traditionally, scaffolds constructed second-order nucleophilic substitution (SN2) reaction condensation piperidine derivatives.10–12 However, most these reactions racemic chiral auxiliary-assisted processes. formed conveniently introducing substituents into ring,13 but scope method rather limited available source starting materials. Catalytic emerged powerful tool transformation planar aromatic compounds highly enantio-enriched three-dimensional molecules.14–49 our ongoing investigate transition-metal-catalyzed reactions, several straightforward protocols access spiroindolenine spiroindoline were revealed.50–53 Recently, we reported unprecedented synthesis indole-annulated, medium-sized ring tetrahydro-γ-carboline- hexahydroazepino[4,3-b]indole-derived carbonates via cascade Ir-catalyzed dearomatization/retro-Mannich/hydrolysis (Scheme 1a).54 Notably, intermediate I was reactive could not isolated. We envisaged if tetrahydro-β-carboline-derived employed protocol, retro-Mannich should avoided due existence two methylene groups between indole nitrogen atom. As consequence, interesting indolenine-fused 2 might afforded major 1b). Herein, report derivatives. Scheme design plan study. Results Our study commenced with evaluation using tetrahydro-β-carboline derivative 1a substrate system consisting iridium precursor [2 mole percent (mol %)] phosphoramidite ligand (4 mol %) tetrahydrofuran (THF) at 50 °C (Table 1).55–85 First, influence ( L1–L8) considered Cs2CO3 (100 base (entries 1–8). L1)86 occurred smoothly (entry 1), delivering product 2a yield (74%) moderate dr value (5.2/1). both diasteroisomers enantiopurity (95% generated L2 Alexakis L3),87 respectively, lead comparable diasteroisomers. dropped slightly 3). addition, Me-THQphos L4) BHPphos L5) developed less terms 4 5). Further more L6–L8) only gave poor 6–8). order improve reaction, bases including DBU, K3PO4, K2CO3, KOAc, NaOAc tested 9–13). found best choice concerning (74%), (7.9/1 ee isomer 96% minor isomer) 13). When no used, completed even after 48 h 14). Inspired work Hartwig co-workers,88 effect counteranion complex examined adding silver salts AgOAc, AgSO3Me, AgOTf, AgBF4 15–18). To delight, all cases, single diastereoisomer. Of particular note, absence base, AgOAc give almost same results 19), while AgSO3Me just 20). Finally, optimal determined described entry 19, where desired isolated 86% ee. Table Optimization Conditionsa Entry L Base Time (h) Yield (%)b drc (major) (%)d (minor) L1 3 74 5.2/1 95 82 4.4/1 94 L3 76 2.9/1 97 4e L4 14 24 8.8/1 / 5e L5 18 5.0/1 6 L6 1.4/1 96 99 7 L7 19 >99 8 L8 42 28 3.0/1 89 85 9 DBU 73 93 10 K3PO4 80 5.4/1 11 K2CO3 6.0/1 12 KOAc 4.5/1 13 7.9/1 23 4.0/1 15f 16g 17h 68 71 18i 83 19/1 91 19f (86j) 20g 6.7/1 Notes: aReaction conditions: (0.2 mmol), (2 %), (2.0 mL) °C. Catalyst prepared nPrNH2 activation.60bCombined diastereoisomers proton nuclear magnetic resonance (1H NMR) analysis CH2Br2 (0.1 mmol) internal standard. cDetermined 1H NMR crude mixtures. dDetermined high-performance liquid chromatography (HPLC) stationary phase. eIn refluxing dioxane. fWith (8 %). gWith hWith AgOTf iWith jIsolated yield. Under optimized conditions, tethered explored examine generality 2). Substrates bearing varied 4-, 5-, 6-position moiety proceed their corresponding yields, diastereo- 2a–2l, 68%–92% 14/1 dr, 88%–96% values lower when seven-substituted indole-derived substrates used 2m, 72% yield, 6/1 95% ee; 2n, 16/1 88% electronic property does show notable influence. either electron-withdrawing (F Cl) electron-donating (Me, MeO, BnO) well tolerated. Moreover, tryptophan-derived substrates, which contain one center ring, underwent smoothly, affording 2o–2q, 91%–96% 8/1 dr). relatively 2q probably caused mismatch R configuration 1q (S,S,Sa)- transition state. gem-dimethyl carboline 2r combined (94%) (>99% [major isomer] 99% [minor isomer]), (1.8/1 carbonate skipped (m = 2), target proceeded well. diastereomeric ratios despite high enantiomeric purity 2s, 71% 94% isomer], 1.1/1 dr; 2t, 69% 1.5/1 stereochemistry 2p (4R,4aR,11S) (4R,4aR,11R) established Overhauser enhancement spectroscopy X-ray crystallographic analysis, respectively.89 absolute other (major isomers) assigned analogy. Substrate scope. activation.60 Combined reported. analysis. Enantiomeric excess (ee) generally exhibit 20/1 It known catalyst Feringa-type control position. utilized, Si-face position allowed attacked. it facial selectivity prochiral nucleophile determines obtained. At stage, calculations90 (M06-2X/SDD/6-31G**) shed some light selectivity. formation selected Two states, TS-2a-( Si ) Re ), leading (4R,4aR) (4R,4aS) 2a, located calculated Gibbs free energy than 1.2 kcal/mol, agreement experimental results. structure relative positively charged allyl electron-rich –synclinal [defined dihedral angle D (Ca–Cb–Cc–Cd), below]. favorable interaction overlapped parts exist help stabilize On hand, antiperiplanar conformation, thus, stabilization expected structure. believe inherent preference 2a.91 noted, strength weak nonbonding sensitive external perturbations. reasonable different solvents counter anions Ir-catalyst employed. Optimized structures Si, Si) Re) (in kcal/mol). (a) (b) side views; (c) (d) Newman projection along forming Cb–Cc bond. associated Ir omitted clarity. green pink, respectively. additional introduced certain positions significantly 2r, 1.8/1 Similar computational investigations applied models. shown 4, difference competitive states TS-2r-( isomers reduced 0.8 kcal/mol. geometric similar ). (–synclinal) (antiperiplanar). causes stronger steric repulsion formal case, exemplified closer hydrogen atom pairs (B[H1⋯H4] 2.15 Å, B(H3⋯H4) 2.09 B[H5⋯H6] 2.10 Å) compared (B[H2⋯H4] 2.37 B[H3⋯H4] 2.16 2.06 Å). brought about overlap diminished energetic gap reduces. situation elongated tether very For state TS-2s'-( keep (–synclinal), strain must suffered bridged cyclic conformation require strong strain.92 minimized 0.3 5 short, qualitatively reproduced trend observed three kinds largely originates beneficial states. will lowered stabilizing neutralized operating Synthetic applications demonstrate utility newly gram-scale carried out. standard 1p 3.76 mmol scale 76% (0.85 g) Gram-scale herein readily transformations Subjecting Pd/C-catalyzed hydrogenation 87% dr. Reduction sodium cyanoborohydride furnished 77% meantime, imine easily converted enamine reacting methyl chloroformate. Transformations products. Conclusion summary, enantioselective Ir-catalyzed, intramolecular, general, diastereoselectivity, spectrum conditions. DFT calculations propose working accounting stereoselectivity. Conflicts Interest authors declare competing interests. Acknowledgments thank National Research Development Program China (2016YFA0202900), Basic (2015CB856600), Natural Foundation (21332009, 21572252, 21772219), Technology Commission Municipality (16XD1404300, 18QA1404900, 16490712200), Strategic Priority (XDB20000000), Frontier Sciences (QYZDYSSWSLH012), Youth Promotion Association (2017302) generous financial support. References 1. Maehara S.; Simanjuntak P.; Kitamura C.; Ohashi K.; Shibuya H.Bioproduction Cinchona Alkaloids Endophytic Fungus Diaporthe sp. Associated Ledgeriana.Chem. Pharm. Bull.2012, 60, 1301–1304. Google Scholar 2. Díaz J. G.; Sazatornil Rodríguez M. L.; Mesía L. R.; Arana G. V.Five New Leaves Remijia p eruviana.J. Nat. Prod.2004, 67, 1667–1671. 3. Sim D. S.-Y.; Chong K.-W.; Nge C.-E.; Low Y.-Y.; K.-S.; Kam T.-S.Cytotoxic Vobasine, Tacaman, Corynanthe-Tryptamine Bisindole Tabernaemontana Structure Revision Tronoharine.J. Prod.2014, 77, 2504–2512. 4. Shi M.; Xu Y.-M.Catalytic, Baylis–Hillman Imines Methyl Vinyl Ketone Acrylate.Angew. Chem. Int. Ed.2002, 41, 4507–4510. 5. Jacobsen E. N.; Markó I.; Mungall W. Schröeder K. B.Asymmetric Dihydroxylation Ligand-Accelerated Catalysis.J. Am. Soc.1988, 110, 1968–1970. 6. O'Donnell J.; Wu Huffman C.A Active Species Alkylation Phase-Transfer Catalysis.Tetrahedron1994, 50, 4507–4518. 7. Trampuz A.; Jereb Muzlovic Prabhu R. M.Clinical Review: Severe Malaria.Crit. Care2003, 7, 315–323. 8. Dorman S. E.; Cannon Telford Frank Churchill H.Fulminant Babesiosis Treated Clindamycin, Quinine, Whole-Blood Exchange Transfusion.Transfusion2000, 40, 375–380. 9. Hamama El-Magid O. Zoorob H. H.Chemistry Quinuclidines Nitrogen Bicyclic Bridged-Ring Structures.J. Heterocyclic. Chem.2006, 43, 1397–1420. 10. 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Language: Английский

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Visible-Light-Driven Dearomatization Reaction toward the Formation of Spiro[4.5]deca-1,6,9-trien-8-ones

Organic Letters, Journal Year: 2020, Volume and Issue: 22(2), P. 528 - 532

Published: Jan. 7, 2020

A visible-light-driven regioselective dearomative cyclization between 2-benzyl-2-bromomalonate and alkynes under mild conditions leading to the formation of spiro[4,5]decanes has been developed. In presence H2O, a variety 2-benzyl-2-bromomalonates smoothly undergo 5-exo-dig radical with afford corresponding in moderate good yield step-economical manner oxidant-free conditions.

Language: Английский

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