Enantioselective Aziridination of Unactivated Terminal Alkenes Using a Planar Chiral Rh(III) Indenyl Catalyst

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(2), С. 1447 - 1454

Опубликована: Янв. 3, 2024

Chiral aziridines are important structural motifs found in natural products and various target molecules. They serve as versatile building blocks for the synthesis of chiral amines. While advances catalyst design have enabled robust methods enantioselective aziridination activated olefins, simple abundant alkyl-substituted olefins pose a significant challenge. In this work, we introduce novel approach utilizing planar rhodium indenyl to facilitate unactivated alkenes. This transformation exhibits remarkable degree functional group tolerance displays excellent chemoselectivity favoring alkenes over their counterparts, delivering wide range enantioenriched high-value aziridines. Computational studies unveil stepwise mechanism which alkene migratory insertion plays central role. process results formation strained four-membered metallacycle serves both enantio- rate-determining steps overall reaction.

Язык: Английский

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Catalytic, asymmetric carbon–nitrogen bond formation using metal nitrenoids: from metal–ligand complexes via metalloporphyrins to enzymes

Chemical Science, Год журнала: 2023, Номер 14(44), С. 12447 - 12476

Опубликована: Янв. 1, 2023

The introduction of nitrogen atoms into small molecules is fundamental importance and it vital that ever more efficient selective methods for achieving this are developed. With aim, the potential nitrene chemistry has long been appreciated but its application constrained by extreme reactivity these labile species. This liability however can be attenuated complexation with a transition metal resulting nitrenoids have unique highly versatile which includes amination certain types aliphatic C-H bonds as well reactions alkenes to afford aziridines. At least one new chiral centre typically formed in processes development catalysts exert control over enantioselectivity nitrenoid-mediated become growing area research, particularly past two decades. Compared some synthetic methods, nitrenoid notable chemists draw from diverse array metals , ranging metal-ligand complexes, bearing variety ligand types, via bio-inspired metalloporphyrins, all way through to, very recently, engineered enzymes themselves. In latter category particular, rapid progress being made, rate suggests approach may instrumental addressing outstanding challenges field. review covers key developments strategies shaped field, addition latest advances, up until September 2023.

Язык: Английский

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Aziridination via Nitrogen-Atom Transfer to Olefins from Photoexcited Azoxy-Triazenes

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(14), С. 9499 - 9505

Опубликована: Март 24, 2024

Herein, we report that readily accessible azoxy-triazenes can serve as nitrogen atom sources under visible light excitation for the phthalimido-protected aziridination of alkenes. This approach eliminates need external oxidants, precious transition metals, and photocatalysts, marking a departure from conventional methods. The versatility this transformation extends to selective both activated unactivated multisubstituted alkenes varying electronic profiles. Notably, process avoids formation competing C–H insertion products. described protocol is operationally simple, scalable, adaptable photoflow conditions. Mechanistic studies support idea photofragmentation results in generation free singlet nitrene. Furthermore, mild photoredox-catalyzed N–N cleavage protecting group furnish aziridines reported. Our findings contribute advancement sustainable practical methodologies synthesis nitrogen-containing compounds, showcasing potential broader applications synthetic chemistry.

Язык: Английский

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Chiral Cp^xRhodium(III)‐Catalyzed Enantioselective Aziridination of Unactivated Terminal Alkenes

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(12)

Опубликована: Янв. 27, 2024

Chiral cyclopentadienyl-rhodium(III) Cp

Язык: Английский

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Asymmetric phase-transfer catalysis

Nature Reviews Chemistry, Год журнала: 2024, Номер 8(11), С. 851 - 869

Опубликована: Окт. 9, 2024

Язык: Английский

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Aspartyl β-Turn-Based Dirhodium(II) Metallopeptides for Benzylic C(sp³)–H Amination: Enantioselectivity and X-ray Structural Analysis

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(22), С. 12377 - 12385

Опубликована: Май 22, 2023

Amination of C(sp3)–H bonds is a powerful tool to introduce nitrogen into complex organic frameworks in direct manner. Despite significant advances catalyst design, full site- and enantiocontrol molecular regimes remain elusive using established systems. To address these challenges, we herein describe new class peptide-based dirhodium(II) complexes derived from aspartic acid-containing β-turn-forming tetramers. This highly modular system can serve as platform for the rapid generation chiral libraries, illustrated by facile synthesis series 38 catalysts. Critically, present first crystal structure tetra-aspartate complex, which unveils retention β-turn conformation peptidyl ligand; well-defined hydrogen-bonding network evident, along with near-C4 symmetry that renders rhodium centers inequivalent. The utility this enantioselective amination benzylic bonds, state-of-the-art levels enantioselectivity up 95.5:4.5 er are obtained, even substrates challenges previously reported Additionally, found be competent catalysts intermolecular N-alkylamides via insertion bond α amide nitrogen, yielding differentially protected 1,1-diamines. Of note, type was also observed occur on functionalities itself absence substrate but did not appear detrimental reaction outcomes when present.

Язык: Английский

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Amino Acid-Derived Ionic Chiral Catalysts Enable Desymmetrizing Cross-Coupling to Remote Acyclic Quaternary Stereocenters

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(30), С. 16796 - 16811

Опубликована: Июль 20, 2023

Synthetic application of asymmetric catalysis relies on strategic alignment bond construction to creation chirality a target molecule. Remote desymmetrization offers distinctive advantages spatial decoupling catalytic transformation and generation stereogenic element. However, such separation presents substantial difficulties for the chiral catalyst discriminate distant enantiotopic sites through reaction three or more bonds away from prochirality center. Here, we report strategy that establishes acyclic quaternary carbon stereocenters cross-coupling reactions at distal positions aryl substituents. The new class amino acid-derived ionic catalysts enables desymmetrizing (enantiotopic-group-selective) Suzuki-Miyaura reaction, Sonogashira Buchwald-Hartwig amination between diverse diarylmethane scaffolds aryl, alkynyl, coupling partners, providing rapid access enantioenriched molecules project substituents widely spaced in three-dimensional space. Experimental computational investigations reveal electrostatic steering substrates by C-terminus ligands interactions. Cooperative ion-dipole interactions catalyst's amide group potassium cation aid preorganization transmits asymmetry product. This study demonstrates it is practical achieve precise long-range stereocontrol engineering arrangements catalysts' substrate-recognizing groups metal centers.

Язык: Английский

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Tertiary Amides as Directing Groups for Enantioselective C−H Amination using Ion‐Paired Rhodium Complexes

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(14)

Опубликована: Фев. 13, 2024

Abstract Enantioselective C−H amination at a benzylic methylene is vital disconnection towards chiral benzylamines. Here we disclose that butyric and valeric acid‐derived tertiary amides can undergo highly enantioselective using an achiral anionic Rh complex ion‐paired with Cinchona alkaloid‐derived cation. A broad scope of compounds be aminated encompassing numerous arene substitutions, amides, two different chain lengths. Excellent tolerance ortho substituents was observed, which has not been achieved before in asymmetric intermolecular Rh. We speculate the amide group substrate engages hydrogen bonding interactions directly cation, enabling high level organisation transition state for amination. This contrast our previous work where bearing bond donor required. Control experiments led to discovery methyl ethers also function as proficient directing groups under optimised conditions, potentially acting acceptors. finding promise dramatically expand applicability catalysts.

Язык: Английский

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Enantioselective Phase-Transfer-Catalyzed Synthesis of Spirocyclic Azetidine Oxindoles

Organic Letters, Год журнала: 2024, Номер 26(10), С. 2079 - 2084

Опубликована: Март 6, 2024

Spiro-3,2′-azetidine oxindoles combine two independently important pharmacophores in an understudied spirocyclic motif that is attractive for medicinal chemistry. Here, the enantioselective synthesis of these structures achieved up to 2:98 er through intramolecular C–C bond formation, involving activation substrate with a novel SF5-containing chiral cation phase-transfer (PT) catalyst. The products are readily elaborated/deprotected afford medicinally relevant enantioenriched compounds. Control experiments suggest interfacial PT mechanism, whereby catalytic asymmetric induction chloride leaving group.

Язык: Английский

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Intermolecular amination of Ethyl Benzo ylacetate via photocatalytic nitrene transfer reactions

Organic Chemistry Frontiers, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

This study reports a photocatalytic nitrene transfer reaction of 1,3-dicarbonyl. A broad range substrates and iodinanes are shown, enabling direct C–H functionalization without the need for pre-formed nucleophilic enolate equivalents.

Язык: Английский

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