Dioxazolones: Stable Substrates for the Catalytic Transfer of Acyl Nitrenes

ACS Catalysis, Год журнала: 2020, Номер 10(8), С. 4751 - 4769

Опубликована: Март 30, 2020

Dioxazolones are a convenient class of acyl nitrene transfer reagents. Their application in homogeneous transition-metal catalysis has led to many new amidation reactions. typically activated by transition metals at relatively low reaction temperatures. The metal nitrenoids formed decarboxylative activation dioxazolones generally electron deficient and commonly react concerted fashion. "Intermolecular" insertion reactions involving preactivated C–H bonds ("inner-sphere" mechanism) easily compete with the Curtius-type rearrangement, but for intramolecular "direct" transfer/insertion nonpreactivated substrates (i.e., without preceding formation metal–carbon or metal–hydride bonds) extensive ligand optimization is important prevent such unwanted side ease dioxazolone synthesis, CO2 gas as sole byproduct from dioxazolones, importance general development several interesting producing N-aryl amides, oxazoles, lactams. Since proceeds under mild conditions, stereo- enantioselective also possible, which useful synthesis bioactive nitrogen-containing compounds. This review provides an overview these reported recent years.

Язык: Английский

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Cp*Co(III)/MPAA-Catalyzed Enantioselective Amidation of Ferrocenes Directed by Thioamides under Mild Conditions

Organic Letters, Год журнала: 2019, Номер 21(6), С. 1895 - 1899

Опубликована: Март 6, 2019

Cp*Cobalt(III)-catalyzed enantioselective C-H amidation of ferrocenes using monoprotected amino acids (MPAAs) as chiral ligands was developed. The reaction performed under mild conditions in high yields (up to 97%) with moderate enantioselectivity 77.5:22.5 er), providing a promising strategy create planar chirality via base-metal-catalyzed activation.

Язык: Английский

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Weak-Coordination in C–H Bond Functionalizations Catalyzed by 3d Metals

ACS Catalysis, Год журнала: 2022, Номер 12(6), С. 3452 - 3506

Опубликована: Март 3, 2022

Transition-metal-catalyzed C–H bond functionalizations have had an enormous influence on organic synthesis in recent times. However, the use of low-abundance 4d and 5d metals is almost inevitable, they are high demand. This will be a cause concern, hence, it important to develop methods based 3d metals, which widely present Earth's crust. In this regard, metal catalysts or their precursors for catalysis, general, functionalizations, particular, has gained significant momentum The major development catalytic with been achieved predominantly strongly coordinating directing groups such as pyridyl, pyrimidinyl, pyrazolyl, 8-amino-quinolinyl groups. Thus, prefunctionalization substrates these necessary, contradicts step- atom-economy activation. commonly available functional aldehyde, ketone, carboxylic acid, amide, hydroxy, N-oxides loosely bind through weak-coordination. These weakly orient activate regioselectively without need preinstalled Although challenging, contemporary topic actively pursued by many researchers Through article, we provide comprehensive overview metal-catalyzed, coordinating, directing-group-enabled reported until March 2021.

Язык: Английский

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Achiral Cp^xIr(III)/Chiral Carboxylic Acid Catalyzed Enantioselective C–H Amidation of Ferrocenes under Mild Conditions

ACS Catalysis, Год журнала: 2020, Номер 10(13), С. 7117 - 7122

Опубликована: Июнь 12, 2020

Ir(III)-catalyzed enantioselective C–H activation generally relies on the combination of chiral Ir(III) cyclopentadienyl complexes with carboxylic acids to ensure high enantiocontrol. We report herein achiral CpxIr(III)-catalyzed amidation ferrocenes. Crucial enantioselectivity is use a acid ligand derived from tert-leucine via Pd(II)-catalyzed γ-C(sp3)–H arylation and sterically more hindered CpxIr(III) catalyst. This reaction proceeds smoothly under very mild conditions (0 °C) tolerates wide range ferrocene carboxamides dioxazolones, providing products in good yields (up 97.5:2.5 er). protocol might open way for asymmetric activation.

Язык: Английский

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Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes

Journal of the American Chemical Society, Год журнала: 2019, Номер 141(38), С. 15240 - 15249

Опубликована: Авг. 29, 2019

Direct synthetic routes to amidines are desired, as they widely present in many biologically active compounds and organometallic complexes. N-Acyl particular can be used a starting material for the synthesis of heterocycles have several other applications. Here, we describe fast practical copper-catalyzed three-component reaction aryl acetylenes, amines, easily accessible 1,4,2-dioxazol-5-ones N-acyl amidines, generating CO2 only byproduct. Transformation dioxazolones on Cu catalyst generates acyl nitrenes that rapidly insert into copper acetylide Cu-C bond rather than undergoing an undesired Curtius rearrangement. For nonaromatic dioxazolones, [Cu(OAc)(Xantphos)] is superior this transformation, leading full substrate conversion within 10 min. direct N-benzoyl amidine derivatives from aromatic proved inactive, but moderate good yields were obtained when using simple copper(I) iodide (CuI) catalyst. Mechanistic studies revealed aerobic instability one intermediates at low loadings, could still performed air most substrates loadings 5 mol %. The herein reported procedure not provides new, practical, route also represents new type C-N formation.

Язык: Английский

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Synthesis of 1-naphthols via Cp*Co(iii)-catalyzed C–H activation and cyclization of sulfoxonium ylides with alkynes

Organic Chemistry Frontiers, Год журнала: 2019, Номер 6(23), С. 3868 - 3873

Опубликована: Янв. 1, 2019

A highly practical synthesis of 1-naphthols was developed via Cp*Co(iii)-catalyzed C–H activation and cyclization between sulfoxonium ylides alkynes.

Язык: Английский

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Ruthenium-Catalyzed Asymmetric N-Acyl Nitrene Transfer Reaction: Imidation of Sulfide

Organic Letters, Год журнала: 2020, Номер 22(10), С. 4021 - 4025

Опубликована: Май 1, 2020

The asymmetric nitrene transfer reaction is a useful and strong tool for the construction of nitrogen functional groups such as N-sulfonyl amide carbamic ester in highly enantioselective manner. On other hand, there substantial limitation this filed: N-acyl via corresponding intermediates still difficult because nitrenes undergo undesired dimerization or Curtius rearrangement. Herein, we achieved imidation sulfides catalytic with (OC)ruthenium–salen complex 2b catalyst 3-substituted 1,4,2-dioxazol-5-ones 1 source. Complex can decompose dioxazolones to desired without any activation heating UV irradiation, generating sulfur atom good excellent enantioselectivities (≤98% ee) diazene isocyanate contamination.

Язык: Английский

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Cu(II)-Catalyzed C–H Amidation/Cyclization of Azomethine Imines with Dioxazolones via Acyl Nitrenes: A Direct Access to Diverse 1,2,4-Triazole Derivatives

Organic Letters, Год журнала: 2022, Номер 24(2), С. 613 - 618

Опубликована: Янв. 3, 2022

We report a Cu(II)-catalyzed C-H amidation/cyclization of azomethine imines with dioxazolones as acyl nitrene transfer reagents under additive- and ligand-free conditions. An array 1,2,4-triazolo[1,5-a]pyridine derivatives were afforded in moderate to good yields excellent functional group tolerance. In addition, scale-up reaction photoluminescence properties discussed.

Язык: Английский

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Cp*Co(III)‐Catalyzed o‐Amidation of Benzaldehydes with Dioxazolones Using Transient Directing Group Strategy

Advanced Synthesis & Catalysis, Год журнала: 2019, Номер 362(5), С. 1195 - 1200

Опубликована: Дек. 10, 2019

Abstract Transition metal‐catalyzed ortho‐ selective C( sp 2 )−H amidation of weakly coordinating aldehydes remains limited to precious metals such as Ir, Rh, Ru, etc. Herein, we put forward a novel report on benzaldehydes employing user‐friendly dioxazolones under cost‐effective and air‐stable Cp*Co(III) catalysis. This catalytic transformation involves transient directing group strategy enhance the ligating capability chelating aldehydes. magnified image

Язык: Английский

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Recent Progress in the C−N Bond Formation via High‐Valent Group 9 Cp*M(III)‐Catalyzed Directed sp² C−H Activation

Asian Journal of Organic Chemistry, Год журнала: 2020, Номер 9(11), С. 1701 - 1717

Опубликована: Авг. 13, 2020

Abstract The presence of nitrogen atom in a wide variety organic compounds called for the use powerful C−H activation strategy C−N bond formation. Pentamethylcyclopentadienyl (Cp*) based, high‐valent, group 9 transition‐metal complexes have shown great potential as catalysts activation/functionalization over years. This minireview summarizes recent progress made context formation via catalytic (sp 2 )C−H with Cp*M(III) (M=Co, Rh and Ir) catalysts. A general plausible mechanism is briefly discussed at beginning, then results are arranged according to metal cobalt, rhodium iridium, respectively.

Язык: Английский

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