Chiral Proton-Transfer Shuttle Catalysts Promoted Enantio­selective Nazarov Cyclization

Synlett, Год журнала: 2022, Номер 34(01), С. 29 - 39

Опубликована: Окт. 24, 2022

Abstract The Nazarov cyclization reaction is a convenient, widely used method for the synthesis of cyclopentenones. In this account, we reviewed our recent efforts on chiral proton-transfer shuttle catalysts promoted enantioselective cyclization. We have synthesized various cyclopenta[b]indoles and α,α′-disubstituted cyclopentenones by means cooperative catalysis Lewis acid spiro phosphoric acid. mechanistic studies revealed that acts as multifunctional catalyst: it co-catalyzes dienone enantioselectively catalyzes enol intermediate via hydrogen-­bonding network. 1 Introduction 2 Enantioselective Cyclization Indole Enones 3 Silicon-Directed 4 Conclusion

Язык: Английский

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Chiral gem-difluoroalkyl reagents: gem-difluoroalkyl propargylic borons and gem-difluoroalkyl α-allenols

Chemical Science, Год журнала: 2023, Номер 14(34), С. 9186 - 9190

Опубликована: Янв. 1, 2023

Chiral fluorinated reagents provide new opportunities for the discovery of drugs and functional materials because introduction a group significantly alters molecule's physicochemical properties. gem-difluoroalkyl fragments (R-CF2-C*) are key motifs in many drugs. However, scarcity synthetic methods types chiral limits applications these compounds. Herein, we report two propargylic borons α-allenols their synthesis by means involving rhodium-catalyzed enantioselective B-H bond insertion reactions carbenes Lewis acid-promoted allenylation reactions. The mild, operationally simple method features broad substrate scope good tolerance. These contain easily transformable boron alkynyl or allenyl moieties thus might facilitate rapid modular construction molecules containing other molecules.

Язык: Английский

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Iron‐Catalyzed Stereoconvergent 1,4‐Hydrosilylation of Conjugated Dienes

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(51)

Опубликована: Ноя. 7, 2023

Stereoconvergent transformation of E/Z mixtures olefins to products with a single steric configuration is great practical importance but hard achieve. Herein, we report an iron-catalyzed stereoconvergent 1,4-hydrosilylation reactions readily available conjugated dienes for the synthesis Z-allylsilanes high regioselectivity and exclusive stereoselectivity. Mechanistic studies suggest that most likely proceed through two-electron redox mechanism. The stereoselectivity ultimately determined by crowded reaction cavity α-diimine ligand-modified iron catalyst, which forces diene coordinate center in cis conformation, turn results generation anti-π-allyl intermediate. mechanism this differs from previously reported mechanisms other related involving radicals or metal-hydride species.

Язык: Английский

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α-Aminocarbene-Mediated Si–H Insertion: Deoxygenative Silylation of Aromatic Amides with Silanes

The Journal of Organic Chemistry, Год журнала: 2022, Номер 88(1), С. 594 - 601

Опубликована: Дек. 15, 2022

While metal carbene-mediated Si–H insertion reactions have become a powerful strategy to build new C–Si bonds, the utilization of α-aminocarbene intermediates generated from readily available precursors in reaction remains longstanding challenge. Herein, we develop practical and general synthesize α-aminosilanes through deoxygenative cross-coupling amides silanes mediated by Sm/SmI2. Given simplicity versatility, this methodology represents fascinating example for effective inert as organic synthesis.

Язык: Английский

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Heterometallic Mg‐Ni‐Mg Complex Promoted Hydrosilylation of Alkenes: Catalytic Performance and Intermediates Characterization^†

Chinese Journal of Chemistry, Год журнала: 2024, Номер 42(18), С. 2133 - 2139

Опубликована: Май 7, 2024

Comprehensive Summary Heteronuclear metal complexes have played an increasingly important role in both small molecules activation and catalytic transformation due to the potential metal‐metal synergies. In this work, we reported that well‐defined Mg‐Ni‐Mg complex [( L Mg) 2 Ni(C H 4 ) ] { = [(DippNCMe) CH] − , Dipp 2,6‐ i Pr C 6 3 } was capable of catalyzing conversion a diverse array terminal alkenes hydrosilylated products anti ‐Markovnikov fashion using PhSiH as silicon source. The stoichiometric reaction heterometallic with one equivalent obtained silyl‐nickel‐monohydride NiH(C )(SiHPhEt)] featuring Ni‐Si‐H‐Mg interaction. Moreover, treatment three equivalents provided silyl‐nickel‐trihydride NiH (SiHPhEt)] hydride‐bridged at fragment. Further reactions resultant silyl‐nickel alkenes, e.g., ethylene styrene, yielded corresponding alkene‐coordinated ], (C )] (CH CHPh)], respectively, elimination PhEtSiH . Based on control experiments, were considered active intermediates hydrosilylation reaction.

Язык: Английский

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