A General and Highly Versatile Heterogeneous Pd-Catalyzed Oxidative Aminocarbonylation of Alkynes with Aromatic and Aliphatic Amines

An efficient heterogeneous catalytic system for the oxidative aminocarbonylation of alkynes and amines in the presence of CO/O2 to afford substituted propiolamides has been developed. The active nanocatalyst, [Pd/Mg3Al-LDH]-300(D), is composed by Pd nanoaggregates (2-3 nm average particle size) stabilized over a partially dehydrated [Mg3Al-LDH] matrix. The methodology has resulted widely applicable, being the first catalytic system, either homogeneous or heterogeneous, able to activate not only aliphatic amines but also poorly-nucleophilic aromatic amines. In fact, >60 substituted propiolamides have been synthesized in good to excellent isolated yields through this methodology, being 27 novel compounds. An important characterization effort (XRD, 27Al MAS NMR, TGA, TPD-CO2, BET area, XPS, HAADF-HRSTEM and HRTEM) and optimization of the synthesis conditions of the optimal catalyst has been performed. This study, together with a series of kinetic and mechanistic essays, indicates that the optimal catalyst is composed by Pd(0) species stabilized in a partially dehydrated/dehydroxylated LDH material with a Mg/Al molar ratio of 3 and a small crystallite size. All the experimental data indicates that the in situ formation of [PdI2] active species in the material surface together with the presence of a matrix with the optimal acid/base properties are key aspects of this process.

Exploring the Versatility of the Amidation of Aryl Acid Fluorides using the Germylamines R3 GeNMe2

The formation of amide bonds is an important process since this linkage is an essential component in proteins, pharmaceuticals, and other medicinally and biologically significant molecules. Recently, it was demonstrated that germylamines R3 GeNR'2 were useful reagents for the conversion of acid fluorides to amides. This transformation occurs readily at room temperature and has a low activation energy. In the present study, the versatility of this amidation reaction with aryl acid fluorides is investigated. A series of thirteen acid fluorides with various substituents on the aromatic ring were reacted with the germylamine Ph3 GeNMe2 and twelve of these were converted to the corresponding amides in high yields, the exception being 1,4-benzenedicarbonyl difluoride. The germylamines Bun 3 GeNMe2 and Pri 3 GeNMe2 also could be used for this interconversion, and both of these species successfully converted 1,4-benzenedicarbonyl difluoride to the corresponding amide. In addition, the crystal structure of Ph3 GeNMe2 is reported. This represents one of only three crystallographically characterized germylamines. The synthesis and 19 F NMR characterization of three fluorogermanes R3 GeF (R=Bun , Pri , and Mes) are also reported herein.

Nickel-Catalyzed Amidation of Aryl Alkynyl Acids with Tetraalkylthiuram Disulfides: A Facile Synthesis of Aryl Alkynyl Amides

Nickel-catalyzed amidation of aryl alkynyl acids using tetraalkylthiuram disulfides as the amine source is described, affording a series of aryl alkynyl amides in good to excellent yields under mild conditions. This general methodology provides an alternative pathway for the synthesis of useful aryl alkynyl amides in an operationally simple manner, which shows its practical synthetic value in organic synthesis. The mechanism of this transformation was explored through control experiments and DFT calculations.

N,N-Diethyl-3-methylbenzamide

The development of new techniques for the preparation of organic compounds is important, with catalytic processes being key to this innovation. The development of copper-based metal-organic frameworks to promote oxidative couplings has allowed the synthesis of amides in a very effective manner. This methodology has been successfully applied to the unique preparation of the bioactive compound N,N-diethyl-3-methylbenzamide, with excellent performance (>99% conversion and 95% yield of pure isolated product) on a preparative scale. The described procedure can be classified as an excellent synthesis (EcoScale) considering environmental and economic factors based on different “green metrics” (atom economy, reaction mass efficiency, materials recovery factor, stoichiometric factor, E-factor).

Synthesis of alkynamides through reaction of alkyl- or aryl-substituted alkynylaluminums with isocyanates

An efficient and facile method for the preparation of alkynamides through Et₃N-catalyzed alumination of alkyl- or aryl-substituted terminal alkynes with AlMe₃ and sequential nucleophilic addition of in situ generated alkynylaluminums to isocyanates is described. This method has the merits of using readily available isocyanates and monosubstituted alkynes, easy access to organoaluminums, short reaction times, and high efficiency. A gram-scale synthesis of the desired alkynamide and its application to the formation of α-methylene-β-lactams demonstrates the synthetic utility of this method.

Catalytic and non-catalytic amidation of carboxylic acid substrates

The present review offers an apt summary of amide bond formation with carboxylic acid substrates by taking advantage of several methods. Carboxamides can be regarded as a substantial part of organic and medicinal chemistry due to their utility in synthesizing peptides, lactams, and more than 25% of familiar drugs. Moreover, they play a leading role in the synthesis of bioactive products with anticancer, antifungal, and antibacterial properties. The data are arranged based on the type and amount of reagents used to conduct amidation and are also divided into the following categories: catalytic amidation of carboxylic acids, non-catalytic amidation, and transamidation.

Palladium-Catalyzed Three-Component Reaction: A Novel Method for the Synthesis of N-Acyl Propiolamides

Palladium-catalyzed three-component reactions between terminal alkynes, isonitriles, and sodium carboxylates have been developed. This novel and operationally simple methodology provides an alternative for the synthesis of N-acyl propiolamide derivatives under mild conditions using isonitriles as the amine source and sodium carboxylates as the oxygen and acyl source.

Cu(ii)-Mediated keto C(sp3)–H bond α-acyloxylation of N,N-dialkylamides with aromatic carboxylic acids

The first example of Cu(ii)-mediated oxidative coupling of aromatic carboxylic acids with the C(sp³)–H bond adjacent to the keto group of N,N-dialkylamides has been developed.

Palladium-Catalyzed Oxidative N-Dealkylation/Carbonylation of Tertiary Amines with Alkynes to α,β-Alkynylamides

The first highly effective Pd/C-catalyzed oxidative N-dealkylation/carbonylation of various aliphatic as well as cyclic tertiary amines with alkynes has been described. The selective sp(3) C-N bond activation of tertiary amines at the less steric side using O2 as a sole oxidant and a plausible reaction pathway for the reaction are discussed. The general and operationally simple methodology provides an alternative for the synthesis of a wide range of alk-2-ynamide derivatives under mild conditions. The present protocol is ecofriendly and practical, and it shows significant recyclability.

Palladium–N-heterocyclic carbene (NHC)-catalyzed synthesis of 2-ynamides via oxidative aminocarbonylation of alkynes with amines

Palladium–NHC compounds catalyzing the oxidative aminocarbonylation of alkynes and amines have been developed with oxygen as the benign oxidant under mild reaction conditions, which led to an efficient approach toward the formation a series of alphatic and aromatic 2-ynamides with high atom efficiency.

Palladium-catalyzed carbonylation of allylamines via C–N bond activation leading to β,γ-unsaturated amides

Pd(Xantphos)Cl₂ has been identified as an efficient catalyst for the direct carbonylation of allylamines via C–N bond activation.