Tandem Cross‐Coupling/Spirocyclization/Mannich‐Type Reactions of 3‐(2‐Isocyanoethyl)indoles with Diazo Compounds toward Polycyclic Spiroindolines

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(2), P. 614 - 621

Published: Nov. 15, 2019

Tandem reactions of Pd-catalyzed cross-coupling 3-(2-isocyanoethyl)indoles with diazoacetates and subsequent spirocyclization/Mannich-type reaction have been developed to assemble polycyclic spiroindoline skeletons. Formation spiroindolenines has proven as the crucial step for following Mannich-type cyclization reaction. Accordingly, a novel approach on chiral phosphoric acid catalyzed toward formation diastereomerically enantiomerically enriched pentacyclic spiroindolines established. Moreover, products are versatile building blocks in synthetic chemistry, demonstrated by synthesis key framework aspidosperma kopsia alkaloids.

Language: Английский

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Recent advances in hydride transfer-involved C(sp³)–H activation reactions

Organic Chemistry Frontiers, Journal Year: 2021, Volume and Issue: 8(6), P. 1364 - 1383

Published: Jan. 1, 2021

This review summarizes the recent progresses (2016–2020) in hydride transfer-enabled C(sp³)–H activation according to reaction types, categorized into intramolecular/intermolecular functionalization, and reduction.

Language: Английский

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Bimetallic Catalytic Asymmetric Tandem Reaction of β‐Alkynyl Ketones to Synthesize 6,6‐Spiroketals

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(12), P. 4017 - 4021

Published: Feb. 4, 2019

Abstract The enantioselective tandem reaction of β,γ‐unsaturated α‐ketoesters with β‐alkynyl ketones was realized by a bimetallic catalytic system achiral Au ΙΙΙ salt and chiral N , ′‐dioxide‐Mg ΙΙ complex. cycloisomerization ketone asymmetric intermolecular [4+2] cycloaddition subsequently occurred, providing an efficient straightforward access to multifunctional 6,6‐spiroketals in up 97 % yield, 94 ee >19/1 d.r. Besides, cycle proposed based on the results control experiments.

Language: Английский

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Asymmetric Dearomatization of Indole by Palladium/PC‐Phos‐Catalyzed Dynamic Kinetic Transformation

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(49), P. 21991 - 21996

Published: Sept. 2, 2020

Abstract A palladium‐catalyzed intermolecular dynamic kinetic asymmetric dearomatization of 3‐arylindoles with internal alkynes was developed the use achiral Xantphos and chiral sulfinamide phosphine ligand ( PC‐Phos ) as co‐ligands. This method could deliver various spiro[indene‐1,3′‐indole] compounds in good yields (up to 95 % yield) up 98 ee . The salient features transformation include readily available substrates, ease scale‐up versatile functionalization products. mechanistic experiments gave some insights on active intermediates.

Language: Английский

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Synthesis of Chiral Spirolactams via Sequential C−H Olefination/Asymmetric [4+1] Spirocyclization under a Simple Co^II/Chiral Spiro Phosphoric Acid Binary System

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(43), P. 23187 - 23192

Published: Aug. 26, 2021

Abstract An unprecedented enantioselective synthesis of spiro‐γ‐lactams via a sequential C−H olefination/asymmetric [4+1] spirocyclization under simple Co II /chiral spiro phosphoric acid (SPA) binary system is reported. A range biologically important are obtained with high levels enantioselectivity (up to 98 % ee ). The concise, asymmetric an aldose reductase inhibitor was successfully achieved. Notably, contrast previous reports that relied on the use cyclopentadienyl or its derivatives (achiral Cp*, Cp tBu , chiral x ) ligated III complexes requiring tedious steps prepare, cheap and commercially available cobalt(II) acetate tetrahydrate used as efficient precatalyst.

Language: Английский

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Palladium/Xu-Phos-catalyzed enantioselective cascade Heck/remote C(sp2) –H alkylation reaction

Chem, Journal Year: 2022, Volume and Issue: 8(3), P. 836 - 849

Published: Jan. 18, 2022

Language: Английский

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Access to 5,6-Spirocycles Bearing Three Contiguous Stereocenters via Pd-Catalyzed Stereoselective [4 + 2] Cycloaddition of Azadienes

Organic Letters, Journal Year: 2021, Volume and Issue: 23(8), P. 2884 - 2889

Published: March 26, 2021

We present herein a highly diastereo- and enantioselective Pd-catalyzed [4 + 2] cycloaddition of benzofuran-derived azadienes with vinyl benzoxazinanones, which represents rare stereoselective this class fused as two-atom synthon. The use phosphoramidite ligand bearing chiral secondary amine simple biphenyl backbone proved to be the key construct novel spirocyclic tetrahydroquinoline scaffold containing three contiguous stereocenters single diastereomer in high enantioselectivity.

Language: Английский

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Ligand-Controlled, Palladium-Catalyzed Asymmetric [4+4] and [2+4] Cycloadditions

Organic Letters, Journal Year: 2021, Volume and Issue: 23(6), P. 2292 - 2297

Published: March 8, 2021

Ligand-controlled, palladium-catalyzed asymmetric [4+4] and [2+4] cycloaddition reactions of benzofuran-derived azadienes have been developed. Taking advantage chiral P,N-ligand (S,Rp)-PPFA, we obtained a variety benzofuro[2,3-c][1,5] oxazocines in good yields with excellent enantioselectivities via reactions. Employing P,P-ligand (S)-Cl-MeO-BIPHEP, the chemo- regioselectivities were switched to synthesize tetrahydropyran-fused spirocyclic compounds efficiency

Language: Английский

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Catalyst Control over Twofold and Higher-Order Stereogenicity by Atroposelective Arene Formation

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(12), P. 2764 - 2774

Published: May 31, 2021

ConspectusContradictory to the first intuitive impression that forging putatively flat aromatic rings evades stereoisomerism, a striking variety of atropisomeric compounds are conceivable by formation arenes, offering captivating avenues for catalyst-controlled stereoselective strategies. Since assembled products contain one or several rotationally restricted single bonds characterized especially well defined molecular architectures, they distinctly suitable numerous pertinent applications. In view fascinating arene-forming aldol condensation pathways taking place in polyketide biosynthesis (cyclases/aromatases (CYC/ARO)), versatile small-molecule-catalyzed reaction appeared as an exceptionally appealing synthetic means prepare various unexplored our efforts presented herein. initial studies, use secondary amine organocatalysts provided excellent selectivities condensations broad range products, such biaryls and amides. further analogy biosynthesis, it was also formed catalytic cascade reactions. The small-molecule catalysts thereby enabled us transfer this concept conversion unnatural noncanonical substrates, thus giving access atropisomers with particular value versatility reactions activation modes strategy individually control stereogenic axes, similar methodologies developed controlling stereocenter configurations. By iterative building block additions combined form rings, stereodivergent catalyst–substrate-matched -mismatched were obtained. Besides amines, cinchona-alkaloid-based quaternary ammonium salts proved be highly efficient overcoming severe substrate bias. obtained multiaxis systems, all biaryl suitably rotation even at high temperatures, spatially defined. helical structure is therefore excellently suited applications.While previous methods distinguish two stereoisomers each unit, catalyst beyond realms dualistic stereoisomerism remained unexplored. selective preparation O̅ki their sixfold stereogenicity Rh-catalyzed [2 + 2 2] cyclotrimerizations, out six possible resulting from bond shown catalytically addressable. Catalyst over higher-order interconnects conformational analysis catalysis offers explore uncharted stereochemical space creating unprecedented motifs.

Language: Английский

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Enantioselective Synthesis of Spirosilabicyclohexenes by Asymmetric Dual Ring Expansion of Spirosilabicyclobutane with Alkynes

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(48)

Published: Oct. 7, 2022

Silaspiranes have attracted particular attention due to their chiral spiro-silicon center, which serves as an ideal carbon isostere and can endow spiro-analogs with distinct properties. Distinct from previously reported cyclization or cycloaddition strategies form 5/5-silaspiranes, we report herein the asymmetric dual ring expansion of spirosilabicyclobutanes alkynes synthesize axially spirosilabicyclohexenes bearing a novel 6/6-silaspirane framework. DFT (density functional theory) calculations provide deep insight into origin high enantioselectivity controlled by sterically demanding binaphthyl phosphoramidite ligand. Preliminary studies chiroptical properties indicate that one spirosilabicyclohexene analogs exhibit fluorescence emission, Cotton effects CPL (circularly polarized luminescence) activity.

Language: Английский

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