Catalysis with Diboron(4)/Pyridine: Application to the Broad-Scope [3 + 2] Cycloaddition of Cyclopropanes and Alkenes

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(19), С. 8870 - 8882

Опубликована: Май 9, 2022

In contrast to the extensive but non-recyclable use of tetraalkoxydiboron(4) compounds as stoichiometric reagents in diverse reactions, this article reports an atom-economical reaction using a commercial diboron(4) catalyst. The key success was designing catalytic cycle for radical [3 + 2] cycloaddition involving pyridine cocatalyst generate from catalyst and reversibly mediate transfer boronyl radicals. comparison with known transition metal-based catalysts, current features not only metal-free conditions, inexpensive stable simple operation also remarkably broadened substrate scope. particular, previously unusable cyclopropyl ketones without activating group and/or alkenes 1,2-disubstitution 1,1,2-trisubstitution patterns were successfully used first time. Consequently, challenging cyclopentane various levels substitution (65 examples, 57 new products, up six substituents at all five ring atoms) readily prepared generally high excellent yield diastereoselectivity. applied concise formal synthesis anti-obesity drug building natural product-like complex bridged or spirocyclic compounds. Mechanistic experiments computational investigation support proposed relay catalysis featuring pyridine-assisted Overall, work demonstrates approach catalysts may lead development new, green, efficient metal-like boron-catalyzed organic reactions.

Язык: Английский

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Decatungstate-catalyzed radical disulfuration through direct C-H functionalization for the preparation of unsymmetrical disulfides

Nature Communications, Год журнала: 2022, Номер 13(1)

Опубликована: Июль 6, 2022

Abstract Unsymmetrical disulfides are widely found in the areas of food chemistry, pharmaceutical industry, chemical biology and polymer science. Due importance such various fields, general methods for nondirected intermolecular disulfuration C-H bonds highly desirable. In this work, conversion aliphatic C(sp 3 )-H aldehydic 2 into corresponding C-SS with tetrasulfides (RSSSSR) as radical reagents is reported. The decatungstate anion ([W 10 O 32 ] 4− ) photocatalyst used C-radical generation via hydrogen atom transfer combination cheap sodium persulfate (Na S 8 oxidant. Herein a series valuable acyl alkyl disulfides, important precursors RSS-anions, unsymmetrical dialkyl synthesized using direct approach. To demonstrate potential method late-stage functionalization, approved drugs natural products were successfully functionalized.

Язык: Английский

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Enantioselective Radical Addition to Ketones through Lewis Acid-Enabled Photoredox Catalysis

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(48), С. 22140 - 22149

Опубликована: Ноя. 22, 2022

Photocatalysis opens up a new window for carbonyl chemistry. Despite multitude of photochemical reactions compounds, visible light-induced catalytic asymmetric transformations remain elusive and pose formidable challenge. Accordingly, the development simple, efficient, economic systems is ideal pursuit chemists. Herein, we report an enantioselective radical photoaddition to ketones through Lewis acid-enabled photoredox catalysis wherein in situ formed chiral N,N'-dioxide/Sc(III)-ketone complex serves as temporary photocatalyst trigger single-electron transfer oxidation silanes generation nucleophilic species, including primary, secondary, tertiary alkyl radicals, giving various enantioenriched aza-heterocycle-based alcohols good excellent yields enantioselectivities. The results electron paramagnetic resonance (EPR) high-resolution mass spectrum (HRMS) measurements provided favorable evidence stereocontrolled addition process involved this reaction.

Язык: Английский

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Catalytic multicomponent reaction involving a ketyl-type radical

Nature Synthesis, Год журнала: 2022, Номер 1(6), С. 464 - 474

Опубликована: Июнь 13, 2022

Язык: Английский

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Diastereoselective and enantioselective photoredox pinacol coupling promoted by titanium complexes with a red-absorbing organic dye

Chemical Science, Год журнала: 2022, Номер 13(20), С. 5973 - 5981

Опубликована: Янв. 1, 2022

The pinacol coupling reaction, a reductive of carbonyl compounds that proceeds through the formation ketyl radicals in presence an electron donor, affords corresponding 1,2-diols one single step. photoredox version this transformation has been accomplished using different organic dyes or photoactive metal complexes sacrificial donors such as tertiary amines Hantzsch's ester. Normally, homo-coupling reactive is neither diastereo- nor enantio-selective. Herein, we report highly diastereoselective reaction aromatic aldehydes promoted by 5 mol% non-toxic, inexpensive and available Cp2TiCl2 complex. key feature allows complete control diastereoselectivity employment red-absorbing dye redox-active titanium Taking advantage well-tailored potential dye, selective reduction Ti(iv) to Ti(iii) achieved. These conditions enable d,l (syn) diastereoisomer favored product (d.r. > 20 : 1 most cases). Moreover, employing simply prepared chiral SalenTi complex, new gave diastereoselection for diastereoisomer, high enantiocontrol (up 92% enantiomeric excess).

Язык: Английский

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Ketyl Radical Coupling Enabled by Polycyclic Aromatic Hydrocarbon Electrophotocatalysts

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(37), С. 20169 - 20175

Опубликована: Сен. 7, 2023

Herein, we report a new class of electrophotocatalysts, polycyclic aromatic hydrocarbons, that promote the reduction unactivated carbonyl compounds to generate versatile ketyl radical intermediates. This catalytic platform enables previously challenging intermolecular coupling reactions, including those classic reductants (e.g., SmI2/HMPA) have failed promote. More broadly, this study outlines an approach fundamentally expand array reactive intermediates can be generated via electrophotocatalysis by obviating need for rapid mesolytic cleavage following substrate reduction.

Язык: Английский

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Molecular Editing of Ketones through N-Heterocyclic Carbene and Photo Dual Catalysis

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(32), С. 22829 - 22839

Опубликована: Авг. 1, 2024

The molecular editing of ketones represents an appealing strategy due to its ability maximize the structural diversity ketone compounds in a straightforward manner. However, developing efficient methods for arbitrary modification ketonic molecules, particularly those integrated within complex skeletons, remains significant challenge. Herein, we present unique recasting that involves radical acylation

Язык: Английский

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Nickel-Catalyzed Defluorinative Coupling of Aliphatic Aldehydes with Trifluoromethyl Alkenes

ACS Catalysis, Год журнала: 2022, Номер 12(4), С. 2463 - 2471

Опубликована: Фев. 3, 2022

A simple procedure is reported for the nickel-catalyzed defluorinative alkylation of unactivated aliphatic aldehydes. The process involves catalytic reductive union trifluoromethyl alkenes with aldehydes using a nickel complex 6,6'-disubstituted bipyridine ligand zinc metal as terminal reductant. protocol distinguished by its broad substrate scope, mild conditions, and setup. Reaction outcomes are consistent intermediacy an α-silyloxy(alkyl)nickel intermediate generated low-valent catalyst, silyl electrophile, aldehyde substrate. Mechanistic findings cyclopropanecarboxaldehyde provide insights into nature reactive intermediates illustrate fundamental reactivity differences that governed subtle changes in structure.

Язык: Английский

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Reductive Cross‐Coupling of α‐Oxy Halides Enabled by Thermal Catalysis, Photocatalysis, Electrocatalysis, or Mechanochemistry

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(34)

Опубликована: Июль 11, 2022

Herein, we report a reductive cross-coupling reaction of α-oxy halides, simply generated from aldehydes, with series C(sp2 )- and C(sp)-electrophiles. A wide range aryl heteroatom vinyl bromides, alkynyl acyl chlorides react unhindered hindered aldehyde-derived halides by providing protected alcohols as well α-hydroxy ketones. Noteworthy, the couplings are achieved not only through thermal catalysis use metal reductants but also photocatalysis, electrochemistry, mechanochemistry. The unrestricted interchange four strategies indicates their underlying mechanistic similarities. generation NiI intermediate is proposed to be key point for ketyl radical formation via single-electron transfer (SET) event, which was rationalized an array control experiments density functional theory (DFT) calculations.

Язык: Английский

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Photoinduced generation of ketyl radicals and application in C–C coupling withoutexternal photocatalyst

Green Chemistry, Год журнала: 2023, Номер 25(10), С. 4129 - 4136

Опубликована: Янв. 1, 2023

A green and efficient procedure for photoinduced generation of ketyl radicals with no use any external photocatalyst is demonstrated, enabling a series important C–C coupling reactions in synthetic chemistry.

Язык: Английский

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