Cobalt-Catalyzed Enantioselective C–H Arylation of Indoles

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(2), P. 798 - 806

Published: Jan. 10, 2022

Atropoisomeric (hetero)biaryls are scaffolds with increasing importance in the pharmaceutical and agrochemical industries. Although it is most obvious disconnection to construct such compounds, direct enantioselective C–H arylation through concomitant induction of chiral information remains extremely challenging uncommon. Herein, unprecedented earth-abundant 3d-metal-catalyzed atroposelective reported, furnishing rare atropoisomeric C2-arylated indoles. Kinetic studies DFT computation revealed an uncommon mechanism for this asymmetric transformation, oxidative addition being rate- enantio-determining step. Excellent stereoselectivities were reached (up 96% ee), while using unusual N-heterocyclic carbene ligand bearing essential remote substituent. Attractive dispersion interactions along positive C–H---π exerted by identified as key factors guarantee excellent enantioselection.

Language: Английский

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Single‐Step Synthesis of Atropisomers with Vicinal C−C and C−N Diaxes by Cobalt‐Catalyzed Atroposelective C−H Annulation

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(39)

Published: Aug. 2, 2022

The atroposelective synthesis of atropisomers with vicinal diaxes remains rare and challenging, due to the steric influence between two axes their unique topology. Herein, we disclose a single-step construction C-C C-N chiral by cyclopentadiene (Cp)-free cobalt-catalyzed intramolecular C-H annulation, providing desired diaxial structures decent stereocontrols both (up >99 % ee 70 : 1 dr). optically pure products bearing fluorophores show circular polarized luminescence (CPL) properties, being candidate materials for potential CPL applications. Atropisomerization experiments density function theory (DFT) calculations are conducted study rotational barriers rotation pathways diaxes.

Language: Английский

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Nitrogen Effects Endowed by Doping Electron-Withdrawing Nitrogen Atoms into Polycyclic Aromatic Hydrocarbon Fluorescence Emitters

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(23), P. 15977 - 15985

Published: May 7, 2024

Unveiling innovative mechanisms to design new highly efficient fluorescent materials and, thereby, fabricate high-performance organic light-emitting diodes (OLEDs) is a concerted endeavor in both academic and industrial circles. Polycyclic aromatic hydrocarbons (PAHs) have been widely used as emitters blue OLEDs, but device performances are far from satisfactory. In response, we propose the concept of "nitrogen effects" endowed by doping electron-withdrawing nitrogen atoms into PAH fluorescence emitters. The presence n orbital on imine conducive promoting electron coupling, which leads increased molar absorptivity an accelerated radiative decay rate emitters, thereby facilitating Förster energy transfer (FET) process OLEDs. Additionally, electronically withdrawing enhances host–guest interactions, positively affecting FET horizontal orientation factor emitting layer. To validate concept, cobalt-catalyzed multiple C–H annulation has utilized incorporate alkynes imine-based frameworks, enables various imine-embedded (IE-PAH) cyclization demonstrates notable regioselectivity, offering practical tool precisely introduce peripheral groups at desired positions with bulky alkyl units positioned adjacent atoms, were previously beyond reach through Friedel–Crafts reaction. Blue OLEDs fabricated IE-PAHs exhibit outstanding performance maximum external quantum efficiency (EQEmax) 32.7%. This achievement sets groundbreaking record for conventional PAH-based EQEmax 24.0%.

Language: Английский

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Renewable resources for sustainable metallaelectro-catalysed C–H activation

Chemical Science, Journal Year: 2020, Volume and Issue: 11(33), P. 8657 - 8670

Published: Jan. 1, 2020

The merger of C–H activation with electrosynthesis, powered by renewable energies and resources, will guide towards a sustainable future.

Language: Английский

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Green strategies for transition metal-catalyzed C–H activation in molecular syntheses

Organic Chemistry Frontiers, Journal Year: 2021, Volume and Issue: 8(17), P. 4886 - 4913

Published: Jan. 1, 2021

Sustainable strategies for the activation of inert C–H bonds towards improved resource-economy.

Language: Английский

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C–H bond functionalization by high-valent cobalt catalysis: current progress, challenges and future perspectives

Chemical Communications, Journal Year: 2021, Volume and Issue: 57(83), P. 10827 - 10841

Published: Jan. 1, 2021

Over the last decade, high-valent cobalt catalysis has earned a place in spotlight as valuable tool for C-H activation and functionalization. Since discovery of its unique reactivity, more attention been directed towards utilization an alternative to noble metal catalysts. In particular, Cp*Co(III) complexes, well simple Co(II) Co(III) salts combination with bidentate chelation assistance, have extensively used development novel transformations. this review, we demonstrated existing trends functionalization methodology using highlighted main challenges overcome, perspective directions, which need be further developed future.

Language: Английский

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Cobalt-Catalyzed Intermolecular C–H Amidation of Unactivated Alkanes

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(13), P. 5191 - 5200

Published: March 29, 2021

Alkanes are an abundant and inexpensive source of hydrocarbons; thus, development new methods to convert the hydrocarbon feedstocks value-added chemicals is high interest. However, it challenging achieve such transformation in a direct selective manner mainly due intrinsic inertness their C–H bonds. We herein report tailored Cp*Co(III)(LX)-catalyzed efficient site-selective intermolecular amidation unactivated hydrocarbons including light alkanes. Electronic modulation cobalt complexes led enhanced efficiency, these effects were theoretically rationalized by FMO analysis presupposed nitrenoid species. Under current protocol, secondary bond selectivity was observed various nonactivated alkanes reverse tertiary preference, which attributed steric demands system that imposes difficulties accessing Experimental computational studies suggested putative triplet Co nitrenoids transferred bonds via radical-like hydrogen abstraction pathway.

Language: Английский

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Enantioselective C−H functionalization reactions enabled by cobalt catalysis

Chem Catalysis, Journal Year: 2022, Volume and Issue: 2(11), P. 2965 - 2985

Published: Sept. 16, 2022

Language: Английский

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Regio- and Stereoselective Reductive Coupling of Alkynes and Crotononitrile

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(50), P. 23001 - 23009

Published: Dec. 8, 2022

A new regio- and stereoselective reductive coupling of alkynes crotononitrile has been developed via visible light organophotoredox cobalt dual catalysis. variety enantioenriched homoallylic nitriles bearing a stereodefined trisubstituted alkene have easily synthesized with good to excellent (up >20:1 rr), stereo- (>20:1 E/Z), enantioselectivity 98% ee) control under mild conditions. The corresponding nitrile products were smoothly converted into various chiral building blocks. Remarkably, simple organic base together water utilized as hydrogen sources in this photoinduced reaction.

Language: Английский

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Sulfoxide-Directed or 3d-Metal Catalyzed C–H Activation and Hypervalent Iodines as Tools for Atroposelective Synthesis

Accounts of Chemical Research, Journal Year: 2023, Volume and Issue: 56(3), P. 189 - 202

Published: Jan. 27, 2023

ConspectusThe expanding applications of atropisomeric compounds combined with the growing diversity such chiral molecules translate into an urgent need for innovative synthetic strategies allowing their rapid, efficient, and sustainable synthesis. Recently, C-H activation approach has provided new opportunities synthesizing axially compounds. The two complementary approaches implementation methodology toward synthesis imply either ortho-functionalization preexisting prochiral or atropo-unstable biaryl substrates direct arylation sterically encumbered aromatics. first required preinstallation a directing group on precursor, which drastically limits thus generated products. To tackle this important limitation, we have envisioned using sulfoxide as both auxiliary. Indeed, in addition to efficiently coordinating Pd-catalyst induction, moiety can be easily removed, via sulfoxide/lithium exchange, after step, guaranteeing almost unlimited postdiversification efficiency generality concept could illustrated by developing atropo-diastereoselective oxidative Heck reaction, acetoxylation, iodination, well arylation. Besides, utility was demonstrated designing expedient steganone precursor. This unique transformation also allowed us build up unprecedented triaryl scaffolds perfectly controlled axes, original skeletons ligand design. While considering atroposelective arylations, clear antagonism between harsh reaction conditions frequently coupling hindered atropo-stability product, resulted scarcity transformations. solve fundamental challenge, focused application low-valent cobalt catalyst, prompted catalyze indoles at C2 position under extremely mild (room temperature). Accordingly, C2-arylation achieved carbene delivering uncommon atropoisomerically pure excellent yields enantioselectivities. Detailed experimental theoretical mechanistic studies shed light mechanism transformation, providing strong evidence regarding origin enantioselectivity. Finally, steric hindrance guarantee molecule couple partners is limitation not only development but C-N Despite long history incredible advances Ullmann-Goldberg Buchwald-Hartwig couplings, versions transformations remained until recently. Our idea challenging issue consisted hypervalent iodines highly reactive partners, desired N-arylations occur room temperature. hypothesis validated reporting Cu-catalyzed N-arylation, λ3-iodanes partners. Subsequently, enantioselective version N-arylation successfully established Cu-complex bearing BOX ligand. In conclusion, report herein tailored-made solutions provide construct molecules, including biaryls molecules.

Language: Английский

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