Recent Advances in Methylation: A Guide for Selecting Methylation Reagents

Chemistry - A European Journal, Journal Year: 2018, Volume and Issue: 25(14), P. 3405 - 3439

Published: Oct. 17, 2018

Methylation is a well-known structural modification in organic and medicinal chemistry. This review summarizes recent advances methylation by categorizing specific reagents. The challenges of mono N-methylation aliphatic amines peptides are discussed. will be useful for chemists wanting to select the appropriate reagents Based on large diversity their wide scope, this also broadens perspectives which strategies utilizing particular methylation, resulting an increased flexibility synthetic route planning.

Language: Английский

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Alcohols as Substrates in Transition-Metal-Catalyzed Arylation, Alkylation, and Related Reactions

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(9), P. 6078 - 6144

Published: April 17, 2024

Alcohols are abundant and attractive feedstock molecules for organic synthesis. Many methods their functionalization require them to first be converted into a more activated derivative, while recent years have seen vast increase in the number of complexity-building transformations that directly harness unprotected alcohols. This Review discusses how transition metal catalysis can used toward this goal. These broadly classified three categories. Deoxygenative functionalizations, representing derivatization C–O bond, enable alcohol act as leaving group formation new C–C bonds. Etherifications, characterized by O–H represent classical reactivity has been modernized include mild reaction conditions, diverse partners, high selectivities. Lastly, chain reactions described, wherein acts mediator formal C–H alkyl backbone. Each these classes transformation will discussed context intermolecular arylation, alkylation, related reactions, illustrating alcohols harnessed

Language: Английский

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Nonbifunctional Outer-Sphere Strategy Achieved Highly Active α-Alkylation of Ketones with Alcohols by N-Heterocyclic Carbene Manganese (NHC-Mn)

Organic Letters, Journal Year: 2019, Volume and Issue: 21(19), P. 8065 - 8070

Published: Sept. 16, 2019

The unusual nonbifunctional outer-sphere strategy was successfully utilized in developing an easily accessible N-heterocyclic carbene manganese (NHC-Mn) system for highly active α-alkylation of ketones with alcohols. This efficient a wide range and alcohols under mild reaction conditions, also the green synthesis quinoline derivatives. direct mechanism high activity present demonstrate potential catalyst design acceptorless dehydrogenative transformations.

Language: Английский

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Catalytic asymmetric C–H insertion reactions of vinyl carbocations

Science, Journal Year: 2022, Volume and Issue: 378(6624), P. 1085 - 1091

Published: Dec. 8, 2022

From the preparation of pharmaceuticals to enzymatic construction natural products, carbocations are central molecular synthesis. Although these reactive intermediates engaged in stereoselective processes nature, exerting enantiocontrol over with synthetic catalysts remains challenging. Many resonance-stabilized tricoordinated carbocations, such as iminium and oxocarbenium ions, have been applied catalytic enantioselective reactions. However, their dicoordinated counterparts (aryl vinyl carbocations) not, despite emerging utility chemical We report discovery a highly carbocation carbon-hydrogen (C-H) insertion reaction enabled by imidodiphosphorimidate organocatalysts. Active site confinement featured this catalyst class not only enables effective but also expands scope cation C-H chemistry, which broadens transition metal-free C(sp

Language: Английский

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Oxidative rearrangement of 1,1-disubstituted alkenes to ketones

Science, Journal Year: 2023, Volume and Issue: 379(6639), P. 1363 - 1368

Published: March 31, 2023

The Wacker process, which is widely used to convert monosubstituted alkenes into the corresponding methyl ketones, thought proceed through a PdII/Pd0 catalytic cycle involving β-hydride elimination step. This mechanistic scenario inapplicable synthesis of ketones from 1,1-disubstituted alkenes. Current approaches based on semi-pinacol rearrangement PdII intermediates are limited ring expansion highly strained methylene cyclobutane derivatives. Herein, we report solution this synthetic challenge by designing PdII/PdIV incorporating 1,2-alkyl/PdIV dyotropic as key reaction, compatible with broad range functional groups, applicable both linear olefins and cycloalkanes, including macrocycles. Regioselectivity favors migration more substituted carbon, strong directing effect β-carboxyl group was also observed.

Language: Английский

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Dual-state emissive imidazo[1,2-α]pyridines with full color emission, acidochromism, viscosity-dependent fluorescence, and bioimaging applications

Dyes and Pigments, Journal Year: 2024, Volume and Issue: 224, P. 112004 - 112004

Published: Feb. 2, 2024

Language: Английский

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Manganese(I)-Catalyzed Cross-Coupling of Ketones and Secondary Alcohols with Primary Alcohols

ACS Omega, Journal Year: 2019, Volume and Issue: 4(6), P. 10741 - 10754

Published: June 20, 2019

Catalytic cross-coupling of ketones and secondary alcohols with primary is reported. An abundant manganese-based pincer catalyst catalyzes the reactions. Low loading (2 mol %) catalytic use a mild base (5-10 are sufficient for efficient cross-coupling. Various aryl heteroaryl catalytically cross-coupled to provide selective α-alkylated products. Challenging α-ethylation also attained using ethanol as an alkylating reagent. Further, direct in reaction results situ oxidation ketone intermediates, which undergo α-alkylation. The proceeds via borrowing hydrogen pathway. oxidizes aldehydes, subsequent aldol condensation ketones, promoted by amount Cs2CO3, α,β-unsaturated intermediates. liberated from used hydrogenation Notably either water or dihydrogen only byproducts these environmentally benign processes. Mechanistic studies allowed inferring all intermediates involved. Dearomatization-aromatization metal-ligand cooperation facilitates facile O-H bond activation both alcohols, resultant manganese alkoxide complexes produce corresponding carbonyl compounds, perhaps β-hydride elimination. manganese(I) hydride intermediate plays dual role it hydrogenates liberates molecular regenerate active dearomatized intermediate. Metal-ligand allows exist same state (+1) important

Language: Английский

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Ruthenium-Catalyzed β-Alkylation of Secondary Alcohols and α-Alkylation of Ketones via Borrowing Hydrogen: Dramatic Influence of the Pendant N-Heterocycle

Organometallics, Journal Year: 2019, Volume and Issue: 38(3), P. 654 - 664

Published: Jan. 28, 2019

Three bidentate ruthenium(II) complexes with a pyridonate fragment were prepared and fully characterized. These are structurally similar, but differ in their pendant substituents. Complex 1 contains phenyl unit, whereas 2 3 have uncoordinated thienyl thiazolyl groups, respectively. tested as catalysts for β-alkylation of secondary alcohols primary alcohols, shows the highest activity, suggesting ring participates catalytic process. Furthermore, is an excellent catalyst α-alkylation ketones alcohols. Various α-alkylated synthesized high yields, by using 0.05 mol % 0.25 equiv t-BuOK within 30 min.

Language: Английский

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Sustainable and Selective Alkylation of Deactivated Secondary Alcohols to Ketones by Non‐bifunctional Pincer N‐heterocyclic Carbene Manganese

ChemSusChem, Journal Year: 2020, Volume and Issue: 13(10), P. 2557 - 2563

Published: March 31, 2020

Abstract A sustainable and green route to access diverse functionalized ketones via dehydrogenative–dehydrative cross‐coupling of primary secondary alcohols is demonstrated. This borrowing hydrogen approach employing a pincer N‐heterocyclic carbene Mn complex displays high activity selectivity. variety are well tolerant result in satisfactory isolated yields. Mechanistic studies suggest that this reaction proceeds direct outer‐sphere mechanism the dehydrogenation alcohol substrates plays vital role rate‐limiting step.

Language: Английский

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Temperature-Controlled Chalcogenation and Chalcogenocyanation of Imidazopyridines in Water under Transition Metal-Free Conditions

The Journal of Organic Chemistry, Journal Year: 2020, Volume and Issue: 85(14), P. 9106 - 9116

Published: June 16, 2020

A sustainable and transition metal-free approach for C3 chalcogenation chalcogenocyanation of imidazopyridines with KXCN (X = S or Se) has been developed under mild conditions. Importantly, this reaction was performed in the presence catalytic iodine aqueous medium, which afforded either chalcogenated chalcogenocyanated temperature control. The current protocol featured a broad substrate scope, organic solvent-free conditions, operational convenience, gram-scale production.

Language: Английский

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