Organic Synthesis Using Nitroxides

Chemical Reviews, Год журнала: 2023, Номер 123(16), С. 10302 - 10380

Опубликована: Авг. 14, 2023

Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R1R2N–O•. The spin distribution over nitroxide N and O atoms contributes to thermodynamic stability of these radicals. presence bulky N-substituents R1 R2 prevents radical dimerization, ensuring their kinetic stability. Despite reactivity toward various transient C some nitroxides can be easily stored under air at room temperature. Furthermore, oxidized oxoammonium salts (R1R2N═O+) reduced anions (R1R2N–O–), enabling them act valuable oxidants reductants depending on oxidation state. Therefore, they exhibit interesting across all three states. Due fascinating properties, find extensive applications in diverse fields such biochemistry, medicinal chemistry, materials science, organic synthesis. This review focuses versatile For use other important fields, we will refer several articles. introductory part provides a brief overview history chemistry. Subsequently, key methods for preparing discussed, followed by an examination structural diversity physical properties. main portion this is dedicated reactions, wherein parent corresponding serve active species. It demonstrated that functional groups (such alcohols, amines, enolates, alkanes among others) efficiently oxidized. These oxidations carried out using catalysts combination stoichiometric terminal oxidants. By reducing anions, become effective reagents intriguing Nitroxides possess ability selectively react making useful terminating cascade reactions forming alkoxyamines. Depending structure, alkoxyamines weak C–O bonds, allowing thermal generation through reversible bond cleavage. Such thermally generated participate transformations, discussed end review. application strategy natural product synthesis presented.

Язык: Английский

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Ethyl lactate-involved three-component dehydrogenative reactions: biomass feedstock in diversity-oriented quinoline synthesis

Green Chemistry, Год журнала: 2020, Номер 22(10), С. 3074 - 3078

Опубликована: Янв. 1, 2020

The biomass feedstock ethyl lactate has been utilized for quinoline synthesis via three-component reactions with anilines and aldehydes. take place efficiently oxidant-/solvent-free EL dehydrogenation, provide only water hydrogen by-products.

Язык: Английский

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Catalyst- and additive-free annulation/aromatization leading to benzothiazoles and naphthothiazoles

Organic Chemistry Frontiers, Год журнала: 2019, Номер 6(17), С. 3060 - 3064

Опубликована: Янв. 1, 2019

Catalyst- and additive-free three-component annulation/aromatization enable a highly efficient entry to naphtho[1,2-d]thiazoles benzo[d]thiazoles.

Язык: Английский

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Photoredox Mediated Acceptorless Dehydrogenative Coupling of Saturated N-Heterocycles

ACS Catalysis, Год журнала: 2019, Номер 9(4), С. 3589 - 3594

Опубликована: Март 14, 2019

We report herein a direct unsymmetric coupling and controllable aromatization reaction of saturated N-heterocycles enabled by synergistic photoredox acid catalysis. The furnishes C2–C3 connected biheterocycles in highly chemo- regioselective manner under rather mild conditions. Mechanistic studies indicated that the proceeded via enamine-iminium leading to exclusively connection.

Язык: Английский

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MOF-Derived Subnanometer Cobalt Catalyst for Selective C–H Oxidative Sulfonylation of Tetrahydroquinoxalines with Sodium Sulfinates

ACS Catalysis, Год журнала: 2019, Номер 9(4), С. 2718 - 2724

Опубликована: Фев. 13, 2019

The development and utilization of reusable base-metal catalysts is a central topic in catalysis. Herein, via catalyst design strategy, we present the preparation highly dispersed acid-resistant subnanometer cobalt (<1 nm) by MOF-templated method, which has been utilized for selective C–H oxidative sulfonylation tetrahydroquinoxalines with odorless sodium sulfinates. transformation enables generation variety sulfonylquinoxalines merits good substrate functional group compatibility, high regio- chemoselectivity, use naturally abundant metal catalyst. work presented offers potential further heterogeneous nanocatalysts fabrication products that are difficult to prepare or inaccessible homogeneous

Язык: Английский

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Iron-Catalyzed Coupling of Methyl N-Heteroarenes with Primary Alcohols: Direct Access to E-Selective Olefins

Organic Letters, Год журнала: 2019, Номер 21(18), С. 7514 - 7518

Опубликована: Авг. 30, 2019

An efficient Fe-catalyzed system is reported for direct α-olefination of methyl-substituted N-heteroarenes with primary alcohols. The catalytic dehydrogenative coupling enables a series functionalized E-olefinated N-heteroaromatics excellent selectivity (>99%). Initial mechanistic studies including deuterium-labeling experiments provide evidence the participation benzylic C-H/D bond

Язык: Английский

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Nickel-Catalyzed Dehydrogenation of N-Heterocycles Using Molecular Oxygen

Organic Letters, Год журнала: 2020, Номер 22(16), С. 6458 - 6463

Опубликована: Авг. 12, 2020

Herein, an efficient and selective nickel-catalyzed dehydrogenation of five- six-membered N-heterocycles is presented. The transformation occurs in the presence alkyl, alkoxy, chloro, free hydroxyl primary amine, internal terminal olefin, trifluoromethyl, ester functional groups. Synthesis important ligand antimalarial drug quinine demonstrated. Mechanistic studies revealed that cyclic imine serves as key intermediate for this stepwise transformation.

Язык: Английский

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Cu(I) Complexes Catalyzed the Dehydrogenation of N-Heterocycles

The Journal of Organic Chemistry, Год журнала: 2024, Номер 89(7), С. 4530 - 4537

Опубликована: Март 14, 2024

A copper-catalyzed method for the dehydrogenation of various nitrogen-containing heterocycles to furnish quinolines and indoles has been developed. range 1,2,3,4-tetrahydroquinolines underwent by employing 2 mol % copper complex Cat 3 as a catalyst using O2 an oxidant at 120 °C in 1,2-dichlorobenzene afford desired quinolines. The enables variety indolines presence 2, 10 TEMPO additive under room temperature tetrahydrofuran high yields. Mechanistic studies suggested that dehydrogenative activity is ascribed formation copper(II) active species from copper(I) complexes oxidized O2, which was proved high-resolution mass spectrometry (HRMS). reaction proceeds via superoxide radical anion (·O2–) electron paramagnetic resonance (EPR) spectrometry. In situ infrared spectroscopy revealed dihydroquinoline intermediate formed 1,2,3,4-tetrahydroquinolines.

Язык: Английский

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Straightforward access to novel indolo[2,3-b]indoles via aerobic copper-catalyzed [3+2] annulation of diarylamines and indoles

Chemical Communications, Год журнала: 2020, Номер 56(18), С. 2807 - 2810

Опубликована: Янв. 1, 2020

Unprecedented direct access to novel 2-diarylaminoindolo[2,3-b]indoles via aerobic copper-catalyzed [3+2] annulation of diarylamines and indoles is demonstrated.

Язык: Английский

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Photoinduced α‐C−H Amination of Cyclic Amine Scaffolds Enabled by Polar‐Radical Relay

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

Опубликована: Апрель 11, 2022

Herein, we report a polar-radical relay strategy for α-C-H amination of cyclic amines with N-chloro-N-sodio-carbamates. The is initiated by in situ generation iminium intermediate using N-iodosuccinimide (NIS) oxidant as an initiator, which then operates through series polar (addition and elimination) radical (homolysis, hydrogen- halogen atom transfer) reactions to enable the challenging C-N bond formation controlled manner. A broad range α-amino were readily accessed excellent regioselectivity, superb applicability was further demonstrated functionalization biologically relevant compounds.

Язык: Английский

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