Copper-catalyzed oxidative amidation between aldehydes and arylamines under mild conditions

Metal-Free Bisamidation of N-Tosylhydrazones with Carboxylic Acids Promoted by Tetrabutylammonium Iodide and tert-Butyl Hydroperoxide

A versatile reaction between N-tosylhydrazones and carboxylic acids to access bisamides is reported. This metal-free, room-temperature reaction was catalyzed by TBAI, while TBHP served as the oxidant. Broad substrate scope and good functional group tolerance are the key features of the strategy. Subsequent intramolecular N-arylation of suitably substituted bisamides readily afforded functionalized 3-indazolones.

Reaction engineering blocks ether cleavage for synthesizing chiral cyclic hemiacetals catalyzed by unspecific peroxygenase

Hemiacetal compounds are valuable building blocks in synthetic chemistry, but their enzymatic synthesis is limited and often hindered by the instability of hemiacetals in aqueous environments. Here, we show that this challenge can be addressed through reaction engineering by using immobilized peroxygenase from Agrocybe aegerita (AaeUPO) under neat reaction conditions, which allows for the selective C-H bond oxyfunctionalization of environmentally significant cyclic ethers to cyclic hemiacetals. A wide range of chiral cyclic hemiacetal products are prepared in >99% enantiomeric excess and 95170 turnover numbers of AaeUPO. Furthermore, by changing the reaction medium from pure organic solvent to alkaline aqueous conditions, cyclic hemiacetals are in situ transformed into lactones. Lactams are obtained under the applied conditions, albeit with low enzyme activity. These findings showcase the synthetic potential of AaeUPO and offer a practical enzymatic approach to produce chiral cyclic hemiacetals through C-H oxyfunctionalization under mild conditions.

Palladium-Catalyzed Chelation-Assisted Aldehyde C-H Bond Activation of Quinoline-8-carbaldehydes: Synthesis of Amides from Aldehydes with Anilines and Other Amines

A palladium-catalyzed chelation-assisted direct aldehyde C-H bond amidation of quinoline-8-carbaldehydes with an amine was developed under mild reaction conditions. A wide range of amides were obtained in good to excellent yields from aldehyde with a variety of aniline derivatives and aliphatic amines. Our methodology was successfully applied to synthesize known DNA intercalating agents and can be easily scaled up to a gram scale.

Synthesis and characterization of rare earth/lithium complexes stabilized by ethylenediamine-bridged bis(phenolate) ligands and their activity in catalyzing amidation reactions

Rare earth/lithium complexes stabilized by ethylenediamine-bridged bis(phenolate) ligands have been synthesized and characterized. In addition to five rare earth/lithium amides isolated as major complexes, two other rare earth/lithium complexes bearing two phenolate ligands were also isolated. The activities of rare earth/lithium amides in catalyzing the amidation of aldehydes and amines were studied, which revealed that the yttrium/lithium complex was highly active for a wide range of substrates, generating 58 examples of amides in 42-99% yields under mild conditions (i.e., room temperature, 3-hour reaction time, additive-free). More importantly, this is the first example of rare earth-based catalysts capable of catalyzing the amidation of primary aliphatic amines.

Diamine-functionalized porous graphene oxide sheets decorated with palladium oxide nanoparticles for the oxidative amidation of aldehydes

C–N coupling between aldehydes and amines by ultra-small PdO NPs adorned diamine functionalized porous GO sheets as retrievable nano-catalyst.

CuI incorporated cobalt ferrite nanoparticles as a magnetically separable catalyst for oxidative amidation reaction

A Cu-incorporated magnetic nanocatalyst has been developed for oxidative amidation of aryl aldehydes with 2-aminopyridine in the presence of TBHP.

TBHP-mediated highly efficient dehydrogenative cross-oxidative coupling of methylarenes with acetanilides

A TBHP-mediated dehydrogenative cross-oxidative-coupling approach has been developed for the synthesis of N-arylbenzamides from methylarenes and acetanilides. This cross-coupling method is free of transition metal catalysts and ligands, and no extra organic solvents are required, which make it an useful and attractive strategy for the straightforward construction of C–N bonds. Besides, this conversion is an important complement to the conventional C–N forming strategies.

Synthesis of N-acetoxy-N-arylamides via diacetoxyiodobenzene promoted double acylation reaction of hydroxylamines with aldehydes

A facile and efficient synthesis of N-acetoxy-N-arylamides through double acylations of hydroxylamines with aldehydes and diacetoxyiodobenzene is reported. The yields of the products are good to excellent.

Nonclassical Routes for Amide Bond Formation

The present review offers an overview of nonclassical (e.g., with no pre- or in situ activation of a carboxylic acid partner) approaches for the construction of amide bonds. The review aims to comprehensively discuss relevant work, which was mainly done in the field in the last 20 years. Organization of the data follows a subdivision according to substrate classes: catalytic direct formation of amides from carboxylic and amines ( section 2 ); the use of carboxylic acid surrogates ( section 3 ); and the use of amine surrogates ( section 4 ). The ligation strategies (NCL, Staudinger, KAHA, KATs, etc.) that could involve both carboxylic acid and amine surrogates are treated separately in section 5 .

Cobalt(ii)-catalyzed oxidative esterification of aldehydes: a cooperative effect between cobalt and iodide ions

Efficient cobalt(ii) catalyzed oxidative alkoxylation of aldehydes leading to the corresponding esters is presented. Mechanism studies provide fresh insights into the cobalt mediated decomposition of TBHP in the presence of the iodide ion.

Direct oxidative amidation of aldehydes with amines catalyzed by heteropolyanion-based ionic liquids under solvent-free conditions via a dual-catalysis process

A heteropolyanion-based ionic liquid catalyzed oxidative amidation of aldehydes with amines via a dual-catalysis pathway has been reported.

Microwave-assisted heteropolyanion-based ionic liquid promoted sustainable protocol to N-heteroaryl amides via N-directing dual catalyzed oxidative amidation of aldehydes

A procedure for the synthesis of N-heteroaryl amides directly from oxidative amidation of aldehydes catalyzed by heteropolyanion-based ionic liquids has been reported. The proposed N-directing dual-catalysis mechanism was briefly investigated.

Anionic phenoxy-amido rare-earth complexes as efficient catalysts for amidation of aldehydes with amines

A series of anionic organo-rare-earth amido complexes stabilized by dianionic phenoxy-amido ligands were synthesized, and their catalytic property for the amidation reactions of aldehydes with amines was explored.

Metal free access to amide compounds via peroxide-mediated NN double bond cleavage of azobenzenes

A direct amidation of aldehydes or benzylamines with azobenzenes through TBHP-mediated NN double bond cleavage of azobenzenes has been developed.