Alkyl Diacyl Research Articles

Copper‐Catalyzed N‐Alkylations of NH‐Sulfoximines Under Visible Light

AbstractA copper‐catalyzed N‐alkylation of NH‐sulfoximines with alkyl diacyl peroxides under blue light LED irradiation is reported. The process has a good functional group tolerance, and the products are obtained in yields ranging from 45–91%.magnified image

Photocatalytic chemo-, regio- & stereoselective olefinic β-C-H decarboxylative alkylation of enamides with diacyl peroxides.

A decarboxylative alkylation of enamides with alkyl diacyl peroxides induced by visible-light is described. The chemo-, regio- and stereoselective olefinic β-C-H alkylation generates a series of primary- and secondary alkylated enamides in yields up to 95%. This transformation bears the advantages of operational simplicity, good functional group compatibility and mild conditions.

Lewis Acid Catalyzed Three‐Component Carbofunctionalization of Styrenes with Diacyl Peroxides and Nucleophiles

AbstractA Lewis acid catalyzed carbofunctionalization of styrenes with diacyl peroxides and nucleophiles, including amines, indoles, trimethoxybenzenes, and carboxylic acid, has been accomplished. A wide range of primary, secondary, and tertiary alkyl diacyl peroxides generated from inexpensive aliphatic acids serve as both simple alkylating reagents and internal oxidants for the synthesis of value‐added amines, indoles, 1,1‐diarylalkanes, and esters in moderate to good yields. This protocol features site selectivity, broad substrate scope, and mild reaction conditions.magnified image

Asymmetric radical carboesterification of dienes

The straightforward strategy of building a chiral C-O bond directly on a general carbon radical center is challenging and stereocontrol of the reactions of open-chain hydrocarbon radicals remains a largely unsolved problem. Advance in this elementary step will spur the development of asymmetric radical C-O bond construction. Herein, we report a copper-catalyzed regioselective and enantioselective carboesterification of substituted dienes using alkyl diacyl peroxides as the source of both the carbon and oxygen substituents. The participation of external acids in this reaction substantially extends its applicability and leads to structurally diverse allylic ester products. This work represents the advance in the key elementary reaction of intermolecular enantioselective construction of C-O bond on open-chain hydrocarbon radicals and may lead to the discovery of other asymmetric radical reactions.

Iron-Catalyzed Alkylazidation of 1,1-Disubstituted Alkenes with Diacylperoxides and TMSN3.

An iron-catalyzed radical alkylazidation of electron-deficient alkenes is reported. Alkyl diacyl peroxides work as the alkyl source, and trimethylsilyl azide acts as the azido reservoir. This method features mild reaction conditions, wide substrate scope, and good functional group tolerance, providing a range of α-azido esters, an α-azido ketone, and an α-azido cyanide in high yields. These azides can be easily transferred into many kinds of amino acid derivatives.

Bu4NI-Catalyzed, Radical-Induced Regioselective N-Alkylations and Arylations of Tetrazoles Using Organic Peroxides/Peresters.

Bu4NI-catalyzed regioselective N2-methylation, N2-alkylation, and N2-arylation of tetrazoles have been achieved using tert-butyl hydroperoxide (TBHP) as the methyl source, alkyl diacyl peroxides as the primary alkyl source, alkyl peresters as the secondary and tertiary alkyl sources, and aryl diacyl peroxides as the arylating source. These reactions proceed without pre-functionalization of tetrazole and in the absence of any metal catalysts. Here, peroxides serve the dual role of oxidants as well as alkylating or arylating agents. Based on DFT calculations, it was found that spin density, transition-state barriers (kinetic control), and thermodynamic stability of the products (thermodynamic control) play essential roles in the observed regioselectivity during N-alkylation. This radical-mediated process is amenable to a broad range of substrates and provides products in moderate to good yields.

Iron-Catalyzed Regioselective Decarboxylative Alkylation of Coumarins and Chromones with Alkyl Diacyl Peroxides

A facile iron-catalyzed decarboxylative radical coupling of alkyl diacyl peroxides with coumarins or chromones has been developed, affording a highly efficient approach to synthesize a variety of α-alkylated coumarins and β-alkylated chromones. The reaction proceeded smoothly without adding any ligand or additive and provided the corresponding products containing a wide scope of functional groups in moderate to excellent yields. This protocol was highlighted by its high regioselectivity, readily available starting materials, and operational simplicity.

Development of BODIPY dyes with versatile functional groups at 3,5-positions from diacyl peroxides via Cu(ii)-catalyzed radical alkylation.

An efficient Cu(ii)-catalyzed, C-H alkylation of BODIPY with a variety of alkyl diacyl peroxides has been developed for the first time, providing a late-stage and straightforward method for controllable synthesis of monoalkylated and dialkylated BODIPYs via a radical process that otherwise is difficult to obtain by literature methods. This chemo- and site-selective transformation will allow for the introduction of a variety of functionalities on the BODIPY core for highly versatile tethering to receptors and to other molecules of interest.

Copper-catalyzed 1,4-alkylarylation of 1,3-enynes with masked alkyl electrophiles.

Classical 1,4-dicarbofunctionalization of 1,3-enynes employs organometallic reagents as nucleophiles to initiate the reaction. We report a copper-catalyzed 1,4-alkylarylation of 1,3-enynes with alkyl diacyl peroxides as masked alkyl electrophiles and aryl boronic acids as nucleophiles, selectively affording structurally diversified tetrasubstituted allenes under mild conditions. Mechanistic studies suggest that an allenyl radical might be involved.

Copper-Catalyzed Radical 1,4-Difunctionalization of 1,3-Enynes with Alkyl Diacyl Peroxides and N-Fluorobenzenesulfonimide.

Many reactions involving allenyl ion species have been studied, but reactions involving allenyl radicals are less well understood, perhaps because of the inconvenience associated with the generation of short-lived allenyl radicals. We describe here a versatile method for the generation of allenyl radicals and their previously unreported applications in the intermolecular 1,4-carbocyanation and 1,4-sulfimidocyanation of 1,3-enynes. With the assistance of the trifunctional reagents, alkyl diacyl peroxides or N-fluorobenzenesulfonimide, a range of synthetically challenging multisubstituted allenes can be prepared with high regioselectivity. These multisubstituted allenes can be easily transformed into synthetically useful structures such as fluorinated vinyl cyanides, lactones, functionalized allenyl amides, 1-aminonaphthalenes, and pyridin-2(1 H)-ones, and several novel transformations are reported. The results of radical scavenger and radical clock experiments are consistent with the proposed allenyl radical pathway. Density functional theory (DFT) and IR spectroscopy studies suggest the formation of an isocyanocopper(II) species in the ligand exchange step. On the basis of the results of IR, DFT, and diastereoselectivity studies, an isocyanocopper(II)/copper(I) catalytic cycle is proposed, which differs from the previously considered Cu(III) mechanism in cyanation reactions.

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes.

A copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction for the synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and terminal alkynes is reported. The alkyl carboxylic acids is for the first time being used as the alkyl azide precursors in the form of alkyl diacyl peroxides. This method avoids the necessity to handle organic azides, as they are generated in situ, making this protocol operationally simple. The Cu(I) catalyst not only participates in the alkyl diacyl peroxides decomposition to afford alkyl azides but also catalyzes the subsequent CuAAC reaction to produce the 1,2,3-triazoles.

Iron-Catalyzed Vinylic C-H Alkylation with Alkyl Peroxides.

A variety of alkyl peresters and alkyl diacyl peroxides, which are readily accessible from carboxylic acids, are utilized as general primary, secondary, and tertiary alkylating reagents for iron-catalyzed vinylic C-H alkylation of vinyl arenes, dienes, and 1,3-enynes. This transformation affords olefinic products in up to 98 % yield with high E/Z values. A broad range of functionalities, including carboxyl, boronic acid, methoxy, ester, amino, and halides, are tolerated. This protocol provides a facile approach to some olefins that are difficult to access, and hence, offers an alternative to existing systems. The synthetic utility of this method is demonstrated by late-stage functionalization of selected natural-product derivatives.

Recent Progress on Radical Decarboxylative Alkylation for Csp3–C Bond Formation

Radical decarboxylation has emerged as an attractive method for the formation of C–C bonds starting from easily accessible carboxylic acids. In this review, we attempt to bring the readers up to date in this rapidly expanding field. Specifically, we will cover recent advances in Csp3–C bond formation via the radical decarboxylation of aliphatic carboxylic acids and their activated forms, such as N-hydroxyphthalimide esters (NHP esters), alkyl diacyl peroxides, alkyl peresters, and aryliodine(III) dicarboxylates. The scope and limitation of these transformations will be discussed, highlighting gaps in knowledge and research and examining the mechanisms underlying radical decarboxylation. We aim to make this review a stepping stone for further development in this field.1 Introduction2 Aliphatic Carboxylic Acids3 N-Hydroxyphthalimide Esters (NHP Esters)4 Alkyl Diacyl Peroxides5 Alkyl Peresters6 Aryliodine(III) Dicarboxylates7 Conclusion

Copper‐Catalyzed Decarboxylative Alkylation of Terminal Alkynes

AbstractA copper‐catalyzed decarboxylative alkylation of terminal alkynes under mild reaction conditions has been reported. Various alkyl diacyl peroxides were applied as the alkyl source for the formation of C(sp3)−C(sp) bond. A range of terminal alkynes including aryl alkynes and alkyl alkynes delivered the alkylated internal alkynes with good to high performances. Mechanism studies suggested that this reaction involves a free radical pathway.magnified image

Iron-Catalyzed Carboamination of Olefins: Synthesis of Amines and Disubstituted β-Amino Acids.

Intermolecular carboamination of olefins with general alkyl groups is an unsolved problem. Diastereoselective carboamination of acyclic olefins represents an additional challenge in intermolecular carboaminations. We have developed a general alkylamination of vinylarenes and the unprecedented diastereoselective anti-carboamination of unsaturated esters, generating amines and unnatural β-amino acids. This alkylamination is enabled by difunctional alkylating reagents and the iron catalyst. Alkyl diacyl peroxides, readily synthesized from aliphatic acids, serve as both alkylating reagents and internal oxidizing agents. A computational study suggests that addition of a nitrile to the carbocation is the diastereoselectivity-determining step, and hyperconjugation is proposed to account for the highly diastereoselective anti-carboamination.

Alkyl Esterification of Vinylarenes Enabled by Visible-Light-Induced Decarboxylation.

A decarboxylative alkyl esterification of vinylarenes induced by visible light is described. A variety of alkyl diacyl peroxides synthesized from readily available aliphatic carboxylic acids are used as not only the oxygenation but also alkylation source. This simple and easy to handle reaction has a wide substrate scope, excellent yields, and works under mild reaction conditions. Carbon dioxide is the sole byproduct. An oxidative quenching process is proposed as the mechanism.

Iron‐Catalyzed Decarboxylative Alkyl Etherification of Vinylarenes with Aliphatic Acids as the Alkyl Source

AbstractBecause of the lack of effective alkylating reagents, alkyl etherification of olefins with general alkyl groups has not been previously reported. In this work, a variety of alkyl diacyl peroxides and peresters generated from aliphatic acids have been found to enable the first iron‐catalyzed alkyl etherification of olefins with general alkyl groups. Primary, secondary and tertiary aliphatic acids are suitable for this reaction, delivering products with yields up to 97 %. Primary and secondary alcohols react well, affording products in up to 91 % yield.

Iron-Catalyzed Decarboxylative Alkyl Etherification of Vinylarenes with Aliphatic Acids as the Alkyl Source.

Because of the lack of effective alkylating reagents, alkyl etherification of olefins with general alkyl groups has not been previously reported. In this work, a variety of alkyl diacyl peroxides and peresters generated from aliphatic acids have been found to enable the first iron-catalyzed alkyl etherification of olefins with general alkyl groups. Primary, secondary and tertiary aliphatic acids are suitable for this reaction, delivering products with yields up to 97 %. Primary and secondary alcohols react well, affording products in up to 91 % yield.

Iron-Catalyzed C–H Alkylation of Heterocyclic C–H Bonds

An efficient, iron-catalyzed C-H alkylation of benzothiazoles by using alkyl diacyl peroxides and alkyl tert-butyl peresters which are readily accessible from carboxylic acids to synthesize 2-alkylbenzothiazoles is developed. This reaction is environmentally benign and compatible with a broad range of functional groups. Various primary, secondary, and tertiary alkyl groups can be efficiently incorporated into diverse benzothiazoles. The effectiveness of this method is illustrated by late-stage functionalization of biologically active heterocycles.

Hydroalkylation of terminal aryl alkynes with alkyl diacyl peroxides

A photo and nickel co-catalyzed hydroalkylation of terminal aryl alkynes enabled Z-preferred olefin synthesis has been developed under mild conditions. Alkyl diacyl peroxides were utilized as a new type of alkylation reagents and afforded Z-olefins as the major products in moderate to good yields.