Coupling Of Carboxylic Acids Research Articles

Asymmetric Oxidative Coupling of Carboxylic Acids to α-Branched Aldehydes

Key words oxidative coupling - amine catalysis - aldehydes - carboxylic acids

Enantioselective Oxidative Coupling of Carboxylic Acids to α-Branched Aldehydes.

A new reactivity in organocatalysis is proposed to account for the coupling of carboxylic acids to α-branched aldehydes by combining primary amine catalysis and an oxidant. The developed methodology is an enantioselective α-coupling of aromatic and aliphatic carboxylic acids to α-branched aldehydes and proceeds in high yields (up to 97%) and for most examples good enantioselectivities (up to 92% ee). On the basis of experimental and mechanistic observations, the role of the primary amine catalyst is discussed.

Coupling of Carboxylic Acids with Ynamides and Subsequent Rearrangement for the Synthesis of Imides/Amides.

A coupling of carboxylic acids with ynamides and subsequent rearrangement for the synthesis of imides and amides is reported. The carboxylic acids could couple with ynamides to form α-acyloxyenamide followed by sulfonyl group migration and Mumm rearrangement to furnish the amides. Additionally, the products could be subjected to further rearrangement to deliver β-keto amides. This metal-free process represents an interesting method for chemical bonds cleavage and regeneration. Furthermore, divergent transformation of products were conducted to deliver an array of compounds.

Visible-Light-Initiated, Photocatalyst-Free Decarboxylative Coupling of Carboxylic Acids with N-Heterocycles.

A general and efficient protocol for direct C-H alkylation and acylation of N-heterocycles, using readily accessible carboxylic acids as radical precursors under visible-light irradiation without a photocatalyst and an additional acid additive, has been developed. This protocol provides expedient access to substituted N-heterocycles under mild and metal-free conditions. Mechanistic experiments indicate that this reaction proceeds through a visible-light-initiated radical chain propagation mechanism.

CuII Complex of a 1,10‐Phenanthroline‐Based Pincer as an Efficient Catalyst for Oxidative Cross Dehydrogenative Coupling of Carboxylic Acids with Unactivated Alkanes

AbstractSynthesis of a well‐defined CuII complex 1 featuring a phenanthroline‐based tridentate scaffold, 2‐pyrazol‐(1,10‐phenanthroline) (L) and studies of its catalytic activity in the cross dehydrogenative coupling of acids with common alkanes to form allylic esters are reported. The complex 1 showed excellent catalytic activity in the oxidative cross dehydrogenative coupling of a wide variety of alkanes with acids to form the corresponding allylic esters in moderate to high yields. Several control experiments along with spectroscopic studies were carried out to characterize catalyst 1 and to explore the plausible mechanistic pathways.

Preparation, structure, and reactivity of bicyclic benziodazole: a new hypervalent iodine heterocycle

A new bicyclic organohypervalent iodine heterocycle derivative of benziodazole was prepared by oxidation of 2-iodo-N,N’-diisopropylisophthalamide with m-chloroperoxybenzoic acid under mild conditions. Single crystal X-ray crystallography of this compound revealed a five-membered bis-heterocyclic structure with two covalent bonds between the iodine atom and the nitrogen atoms. This novel benziodazole is a very stable compound with good solubility in common organic solvents. This compound can be used as an efficient reagent for oxidatively assisted coupling of carboxylic acids with alcohols or amines to afford the corresponding esters or amides in moderate yields.

A Predictive Model for the Decarboxylation of Silver Benzoate Complexes Relevant to Decarboxylative Coupling Reactions.

Decarboxylative coupling reactions offer an attractive route to generate functionalized arenes from simple and readily available carboxylic acid coupling partners, yet they are underutilized due to limitations in the scope of carboxylic acid coupling partner. Here we report that the field effect parameter (F) has a substantial influence on the rate of decarboxylation of well-defined silver benzoate complexes. This finding provides the opportunity to surpass current substrate limitations associated with decarboxylation and to enable widespread utilization of decarboxylative coupling reactions.

Modifying Styrene-maleic Acid Co-polymer for Studying Lipid Nanodiscs by Direct Fluorescent Labeling.

This protocol was developed to functionalize styrene maleic acid (SMA) by direct fluorescent labeling in an easy way, accessible to biochemistry laboratories. This novel method is based on the coupling of carboxylic acids to primary amines using a carbodiimide, a reaction commonly used for protein chemistry. The procedure uses the hydrolyzed styrene-maleic acid copolymer and occurs entirely in aqueous solution with mild conditions compatible with many biomolecules.

Microwave Irradiated Cross Coupling of Carboxylic Acids and Crotyl Bromides: Efficient Application to Make Arachidonic Acid Esters

A microwave irradiated palladium-catalyzed reaction of carboxylic acids and crotyl type bromides creates series of esters in good to high yields. This facile ester synthesis then is applied to make esters from arachidonic acid, salicylic acid, folic acid, and aspirin efficiently.

Oxidative coupling of carboxylic acids or benzaldehydes with DMF using hydrotalicite-derived oxide catalysts

Hydrotalcite-derived (HT-derived) oxide catalysts were synthesised from hydrotalcite-like (HT-like) materials prepared by co-precipitation method (Cu-Al, Cu-Fe, Mg-Al, Mg-Fe, Ni-Fe and Ni-Al) followed by calcination and their catalytic activity was studied for oxidative amidation of carboxylic acids and substituted benzaldehydes with N,N-dimethylformamide (DMF). Catalyst screening was done using benzoic acid and DMF as a model reaction. Subsequently, we have optimised the reaction with different reaction parameters, catalyst loading, temperatures and oxidants. Cu-Fe HT-derived oxide catalyst showed excellent activity towards oxidative amidation using TBHP as an oxidant at 80 °C in 10 h. The fresh and spent catalysts were thoroughly characterised by different analytical techniques; XRD, SEM, HRTEM, TPD, N2 adsorption-desorption isotherm and XPS. Moreover, the catalyst was easily separated by simple filtration and reused up to four cycles without significant loss in catalytic activity.

A comparative study of amide-bond forming reagents in aqueous media – Substrate scope and reagent compatibility

A survey of amidation reagents demonstrating DIC-HOPO, DMT-MM, COMU-collidine, TPTU-NMI, EEDQ, CDI and EDC-Oxyma to be effective for the coupling of carboxylic acids with amines in the presence of water and the absence of problematic dipolar aprotic solvents is reported. DMT-MM was shown to provide the best yields for the coupling of a secondary amine, TPTU-NMI and COMU-collidine for aniline, whilst the combination of DIC with HOPO afforded the broadest substrate scope and the highest yields for a sterically demanding carboxylic acid.

Metal‐Free O‐Arylation of Carboxylic Acid by Active Diaryliodonium(III) Intermediates Generated in situ from Iodosoarenes

AbstractThe metal‐free arylative coupling of carboxylic acids using iodosoarenes without the use of a catalyst and base, which is applicable to even a highly‐polar molecule bearing multiple alcohol groups, is reported. The in situ preparation of the reactive diaryliodonium(III) carboxylates is the important key to this approach, and the introduction of the trimethoxybenzene auxiliary enables both the smooth salt formations and the selective aryl transfer events during the couplings.magnified image

Diphenylsilane as a coupling reagent for amide bond formation

A simple amidation procedure enabling the direct coupling of carboxylic acids to amines using one equivalent of diphenysilane is reported.

Copper-catalyzed oxidative dehydrogenative coupling of carboxylic acids with H-phosphonates: an efficient and practical approach to acyl phosphate esters

A practical method through a copper-catalyzed dehydrogenative coupling of carboxylic acids with H-phosphonates to construct acyl phosphate esters has been developed.

ChemInform Abstract: Copper(I)‐Catalyzed Radical Decarboxylative Imidation of Carboxylic Acids with N‐Fluoroarylsulfonimides.

An efficient copper-catalyzed radical decarboxylative imidation reaction is presented. This strategy is carried out through the copper(I)-catalyzed decarboxylative C(sp3)–N and C(sp2)–N coupling of carboxylic acids with N-fluoroarylsulfonimides. The reaction shows good functional group tolerance and it provides a new approach for decarboxylative imidation. Preliminary mechanistic studies of this transformation suggest an involvement of N-centered radical species.

ChemInform Abstract: Transition‐Metal‐Free Decarboxylative Photoredox Coupling of Carboxylic Acids and Alcohols with Aromatic Nitriles.

AbstractThe scalable reaction has a broad substrate scope, thus tolerating aryl and various hetaryl cyanides as well as functionalized alkyl carboxylic acids, including amino acids, but no keto acids or aryl substituted carboxylic acids.

ChemInform Abstract: Decarboxylative anti‐Michael Addition to Olefins Mediated by Photoredox Catalysis.

Decarboxylative coupling of carboxylic acids with activated olefins has been accomplished using visible light photoredox catalysis. The strategic placement of a radical-stabilizing aromatic group at the β-position of the olefin component biases the regioselectivity of the addition, allowing reliable, facile access to anti-Michael-type products from readily available precursors. The scope of this methodology was demonstrated with a range of carboxylic acids and appropriately substituted olefins and was applied toward a two-step synthesis of the antiarrhythmic agent encainide.

An Overview of the Synthesis of Highly Versatile N-Hydroxysuccinimide Esters

N-Hydroxysuccinimide esters (NHS-esters) are important and widely used tools in various areas of chemistry including peptide synthesis, bioconjugate chemistry, functionalized materials and polymers. The usual strategy employed to prepare these active esters generally relies on the coupling reaction with a carboxylic acid and N-hydroxysuccinimide in the presence of a coupling agent. However, more recently, many other efficient strategies have emerged in the literature. This short review covers the literature devoted to the preparation of these valuable N-hydroxysuccinimide esters. 1 Introduction 2 N-Hydroxysuccinimide Coupling Reaction with Activated Carboxylic Acids 3 Carboxylic Acid Coupling Reaction with Activated N-Hydroxysuccinimide 4 Alcohol and Aldehyde Coupling Reaction with N-Hydroxysuccinimide under Oxidizing Conditions 5 Carbonylative Cross-Coupling Reaction 6 Conclusion

ChemInform Abstract: Palladium‐Catalyzed Room‐Temperature Acylative Suzuki Coupling of High‐Order Aryl Borons with Carboxylic Acids.

AbstractDiarylborinic acids and tetraarylboronates are described as practical aryl source for the Pd‐catalyzed Suzuki coupling of carboxylic acids to yield ketones.

Palladium‐Catalyzed Diverse mono‐Acyloxylation of 5‐Alkyl‐4‐aryl‐thiazole‐2‐carboxylates

AbstractThe palladium‐catalyzed oxidative acyloxylation of 5‐alkyl‐4‐aryl‐thiazole‐2‐carboxylates via a direct ortho‐Csp2−H bond activation has been described with a newly reported radical mechanism. Based on the late‐stage functionalization of the highly substituted thiazoles, the reaction delivered multifarious valuable acyloxylated products with moderate‐to‐excellent yields. The transformation affords highly functionalized substrates, has broad scope of carboxylic acid coupling partners, excellent site‐selectivity, rapid reaction rates, simple operation and mild conditions. The diverse acyloxylation reaction allows rapid access to a plethora of mono‐acyloxylated products from the functionalized thiazoles.