Photocatalytic Synthesis of Diarylmethyl Silanes via 1,6-Conjugate Addition of Silyl Radicals to p-Quinone Methides

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(5), P. 3567 - 3576

Published: Feb. 8, 2022

A novel photocatalytic method for the preparation of diarylmethyl silanes was reported through silyl radicals addition strategy to p-QMs (p-quinone methides). This protocol could tolerate a variety functional groups affording corresponding silylation products with moderate excellent yields. The resulting be easily converted into series bioactive GPR40 agonists and useful precursors synthesis compounds possessing both quaternary carbon centers silicon substituents simple operation. plausible mechanism proposed on basis experimental results previous literature.

Language: Английский

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Rhodium(I) Carbene‐Promoted Enantioselective C−H Functionalization of Simple Unprotected Indoles, Pyrroles and Heteroanalogues: New Mechanistic Insights

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(34)

Published: June 17, 2022

A rhodium(I)-diene catalyzed highly enantioselective C(sp2 )-H functionalization of simple unprotected indoles, pyrroles, and their common analogues such as furans, thiophenes, benzofurans with arylvinyldiazoesters has been developed for the first time. This transformation features unusual site-selectivity exclusively at vinyl terminus arylvinylcarbene enables a reliable rapid synthetic protocol to access distinctive class diarylmethine-bearing α,β-unsaturated esters containing one or two heteroarene-attached tertiary carbon stereocenter in high yields excellent enantioselectivities under mild reaction conditions. Mechanistic studies DFT calculations suggest that, compared aniline substrate, more electron-rich indole substrate lowers C-C addition barrier alters rate-determining step reductive elimination, leading different isotope effect.

Language: Английский

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Catalytic Asymmetric P–H Insertion Reactions

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(36), P. 20031 - 20040

Published: Aug. 29, 2023

Albeit notable endeavors in enantioselective carbene insertion into X–H bonds (X = C, O, N, S, Si, B), the catalytic asymmetric P–H reactions still stand for a long-lasting challenge. By merging transition-metal catalysis with organocatalysis, we achieve scalable transformation between diazo pyrazoleamides and H-phosphine oxides that upon subsequent reduction delivers wide variety of optically active β-hydroxyl phosphine good yields high enantioselectivity. The achiral copper catalyst fosters carbenoid bond, while chiral cinchona alkaloid-derived organocatalyst controls outcome. Density functional theory (DFT) calculations further reveal chelates to organocatalyst, enhances its acidity, accordingly promotes proton transfer. Our work showcases potential combining organocatalysis realize elusive reactions.

Language: Английский

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Asymmetric Cyclopropanation of Primary N-Vinylamides via Carbene Transfer Catalyzed by Cationic Rh(I)/Diene Complexes: An Unexpected Outer-Sphere Mechanism

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(12), P. 9385 - 9396

Published: June 6, 2024

A highly enantioselective intermolecular [2 + 1] cycloaddition of primary N-vinylamides with carbene intermediates was developed by taking advantage cationic rhodium(I)/diene catalysis under mild conditions at room temperature. This cyclopropanation method facilitates rapid access to enantioenriched cyclopropylamides, an important motif in drug discovery, generally good yields and high stereoselectivities (>20:1 dr, up 99% ee). approach employs a rhodium(I) catalyst form pre-equilibrium complex enamide substrate. Kinetic experiments comprehensive density functional theory (DFT) calculations were performed elucidate the reaction mechanism. The kinetic data DFT results support existence resting-state between two substrates. computational studies show that involves interesting, unexpected outer-sphere mechanistic pathway involving sole Rh(I) catalytic cycle major product reveal diazo decomposition step is rate-determining step.

Language: Английский

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Conformational Locking Induced Enantioselective Diarylcarbene Insertion into B−H and O−H Bonds Using a Cationic Rh(I)/Diene Catalyst

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(45)

Published: July 18, 2024

Abstract Transition‐metal‐catalyzed enantioselective transformations of aryl/aryl carbene are inherently challenging due to the difficulty in distinguishing between two arene rings reaction process thus remain largely less explored. The few successful examples reported so far, without exception, have all been catalyzed by Rh(II)‐complexes. Herein, we describe our development a novel cationic Rh(I)/chiral diene catalytic system capable efficient B−H and O−H insertions with diaryl diazomethanes, allowing access broad range gem ‐diarylmethine boranes ethers good yields high enantioselectivities. Notably, previously unattainable asymmetric diarylcarbene insertion into bond was achieved for first time. A remarkable feature this newly designed Rh(I)/diene catalyst bearing ortho ‐amidophenyl substitutents is that it can distinguish through stereochemically selective control π–π stacking interactions. DFT calculations indicate rotation‐restricted conformation complex played an important role highly transformations. This work provides interesting unprecedented stereocontrol mode metal

Language: Английский

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