Construction of C–N bonds from small-molecule precursors through heterogeneous electrocatalysis

Nature Reviews Chemistry, Год журнала: 2022, Номер 6(5), С. 303 - 319

Опубликована: Апрель 25, 2022

Язык: Английский

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Diastereoselective Transfer of Tri(di)fluoroacetylsilanes‐Derived Carbenes to Alkenes

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(25)

Опубликована: Апрель 13, 2022

Stereoselective cyclopropanation reaction of alkenes is usually achieved by metal complexes via singlet-metal-carbene intermediates. However, previous transition-metal-catalyzed with acylsilanes afforded low diastereoselectivity. Herein, we report the first visible-light-induced transition-metal-free terminal trifluoroacetylsilanes and difluoroacetylsilanes. Both aromatic aliphatic as well electron-deficient are suitable substrates for highly cis-selective [2+1] cyclization reaction. A combination experimental computational studies identified triplet carbenes being key intermediates in this transformation. The gram scale late-stage functionalization demonstrated synthetic potential strategy.

Язык: Английский

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Metalloradical Catalysis: General Approach for Controlling Reactivity and Selectivity of Homolytic Radical Reactions

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(20)

Опубликована: Март 13, 2024

Abstract Since Friedrich Wöhler's groundbreaking synthesis of urea in 1828, organic over the past two centuries has predominantly relied on exploration and utilization chemical reactions rooted two‐electron heterolytic ionic chemistry. While one‐electron homolytic radical chemistry is both rich fundamental reactivities attractive with practical advantages, synthetic application been long hampered by formidable challenges associated control reactivity selectivity high‐energy intermediates. To fully harness untapped potential for synthesis, there a pressing need to formulate radically different concepts broadly applicable strategies address these outstanding issues. In pursuit this objective, researchers have actively developing metalloradical catalysis (MRC) as comprehensive framework guide design general approaches controlling stereoselectivity reactions. Essentially, MRC exploits metal‐centered radicals present open‐shell metal complexes catalysts activation substrates generate metal‐entangled key intermediates govern reaction pathway stereochemical course subsequent catalytic processes. Different from conventional transition complexes, operates through utilizing stepwise mechanisms.

Язык: Английский

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Asymmetric Radical Cyclopropanation of α,β-Unsaturated Amides with α-Boryl and α-Silyl Dibromomethanes via Cr(II)-Based Metalloradical Catalysis

Journal of the American Chemical Society, Год журнала: 2025, Номер 147(9), С. 7282 - 7292

Опубликована: Фев. 20, 2025

Transition-metal-catalyzed asymmetric carbene-transfer reactions represent a powerful strategy for synthesizing chiral cyclopropanes. However, current methods predominantly rely on stabilized carbene-bearing α-π-conjugated groups, restricting access to less carbenes, such as α-silyl and α-boryl carbenes. Herein, we present an unprecedented Cr(II)-based metalloradical system the cyclopropanation of α,β-unsaturated amides with dibromomethanes in presence Mn reducing agent. Employing chromium complex, reaction proceeds under mild conditions, yielding cyclopropanes three contiguous stereocenters high diastereo- enantioselectivities. This method features Cr-catalyzed radical-based stepwise mechanism. The broad substrate scope, encompassing various amides, demonstrates protocol's versatility robustness. Mechanistic insights, supported by experimental computational studies, suggest formation α-Cr(III)-alkyl radical intermediates, delineating pathway distinct from that classical concerted cyclopropanations. approach provides tool highly functionalized cyclopropanes, offering potential applications drug discovery development.

Язык: Английский

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Metalloradical Activation of In Situ-Generated α-Alkynyldiazomethanes for Asymmetric Radical Cyclopropanation of Alkenes

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(5), С. 2368 - 2378

Опубликована: Янв. 31, 2022

α-Alkynyldiazomethanes, generated in situ from the corresponding sulfonyl hydrazones presence of a base, can serve as effective metalloradicophiles Co(II)-based metalloradical catalysis (MRC) for asymmetric cyclopropanation alkenes. With D2-symmetric chiral amidoporphyrin 2,6-DiMeO-QingPhyrin optimal supporting ligand, system efficiently activate different α-alkynyldiazomethanes at room temperature highly broad range This catalytic radical process provides general synthetic tool stereoselective construction alkynyl cyclopropanes high yields with both diastereoselectivity and enantioselectivity. Combined computational experimental studies offer several lines evidence support underlying stepwise mechanism Co(II)-catalyzed olefin involving unique α-metalloradical intermediate that is associated two resonance forms α-Co(III)-propargyl γ-Co(III)-allenyl radical. The resulting enantioenriched cyclopropanes, showcased stereospecific transformations, may valuable building blocks organic synthesis.

Язык: Английский

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Intermolecular Metal‐Free Cyclopropanation and Aziridination of Alkenes with XH₂(X=N, C) by Thianthrenation**

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(41)

Опубликована: Авг. 17, 2022

Three-membered cyclic structures are widely existing in natural products and serve as enabling intermediates organic synthesis. However, the efficient straightforward access to such with diversity remains a formidable challenge. Herein, general practical protocol aziridines cyclopropanes synthesis using free XH2 (X=C or N) alkenes by thianthrenation is presented. This metal-free features direct aziridination cyclopropanation unprotected . Free sulfonamides, amides, carbamates, amines, methylene acidic protons, good precursors, providing an attractive alternative for of from easily available starting materials.

Язык: Английский

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Carbene Radicals in Transition-Metal-Catalyzed Reactions

ACS Catalysis, Год журнала: 2023, Номер 13(8), С. 5428 - 5448

Опубликована: Апрель 6, 2023

Discovered as organometallic curiosities in the 1970s, carbene radicals have become a staple modern-day homogeneous catalysis. Carbene exhibit nucleophilic radical-type reactivity orthogonal to classical electrophilic diamagnetic Fischer carbenes. Their successful catalytic application has led synthesis of myriad carbo- and heterocycles, ranging from simple cyclopropanes more challenging eight-membered rings. The field matured employ densely functionalized chiral porphyrin-based platforms that high enantio-, regio-, stereoselectivity. Thus far focus largely been on cobalt-based systems, but interest growing for past few years expand other transition metals. This Perspective covers advances made since 2011 gives an overview coordination chemistry, reactivity, radical species using metal complexes catalysts.

Язык: Английский

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Biomimetic asymmetric catalysis

Science China Chemistry, Год журнала: 2023, Номер 66(6), С. 1553 - 1633

Опубликована: Апрель 25, 2023

Язык: Английский

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Asymmetric Radical Bicyclization for Stereoselective Construction of Tricyclic Chromanones and Chromanes with Fused Cyclopropanes

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(21), С. 11622 - 11632

Опубликована: Май 2, 2023

Asymmetric radical bicyclization processes have been developed via metalloradical catalysis (MRC) to stereoselectively construct chiral chromanones and chromanes bearing fused cyclopropanes. Through optimization of a versatile

Язык: Английский

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Vitamin B₁₂‐Photocatalyzed Cyclopropanation of Electron‐Deficient Alkenes Using Dichloromethane as the Methylene Source**

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(2)

Опубликована: Ноя. 28, 2023

Abstract The cyclopropyl group is of great importance in medicinal chemistry, as it can be leveraged to influence a range pharmaceutical properties drug molecules. This report describes Vitamin B 12 ‐photocatalyzed approach for the cyclopropanation electron‐deficient alkenes using dichloromethane (CH 2 Cl ) methylene source. reaction proceeds good excellent yields under mild conditions, has functional compatibility, and highly chemoselective. scope could also extended preparation D ‐cyclopropyl methyl‐substituted adducts starting from CD 1,1‐dichloroethane, respectively.

Язык: Английский

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