De Novo Synthesis of α-Ketoamides via Pd/TBD Synergistic Catalysis

Precisely controlling the product selectivity of a reaction is an important objective in organic synthesis. α-Ketoamides are vital intermediates in chemical transformations and privileged motifs in numerous drugs, natural products, and biologically active molecules. The selective synthesis of α-ketoamides from feedstock chemicals in a safe and operationally simple manner under mild conditions is a long-standing catalysis challenge. Herein, an unprecedented TBD-switched Pd-catalyzed double isocyanide insertion reaction for assembling ketoamides in aqueous DMSO from (hetero)aryl halides and pseudohalides under mild conditions is reported. The effectiveness and utility of this protocol are demonstrated by its diverse substrate scope (93 examples), the ability to late-stage modify pharmaceuticals, scalability to large-scale synthesis, and the synthesis of pharmaceutically active molecules. Mechanistic studies indicate that TBD is a key ligand that modulates the Pd-catalyzed double isocyanide insertion process, thereby selectively providing the desired α-ketoamides in a unique manner. In addition, the imidoylpalladium(II) complex and α-ketoimine amide are successfully isolated and determined by X-ray analysis, confirming that they are probable intermediates in the catalytic pathway.

Platform for the Immobilizing of Ultrasmall Pd Clusters for Carbonylation: In Situ Self-Templating Fabrication of ZIF-8 on ZnO

Incorporating metal clusters into the confined cavities of metal-organic frameworks (MOFs) to form MOF-supported catalysts has attracted considerable research interest with regard to carbonylation reactions. Herein, a self-templating method is used to prepare the zinc oxide (ZnO)-supported core-shell catalyst ZnO@Pd/ZIF-8. This facile strategy controls the growth of metal sources on the ZIF-8 shell layer and avoids the metal diffusion or aggregation problems of the conventional synthesis method. The characteristics of the catalysts show that the palladium (Pd) clusters are highly dispersed with an average particle size of ≈1.2 nm, making them excellent candidates as a catalyst for carbonylation under mild conditions. The optimal catalyst (1.25-ZnO@Pd/ZIF-8) exhibits excellent activity in synthesizing α, β-alkynyl ketones under 1 atm of carbon monooxide (CO), and the conversion rate of 1, 3-diphenylprop-2-yn-1-one is 3.09 and 3.87 times more than those of Pd/ZIF-8 and Pd2+, respectively, for the first 2 h. Moreover, the 1.25-ZnO@Pd/ZIF-8 is recyclable, showing negligible metal leaching, and, under the conditions used in this investigation, can be reused at least five times without considerable loss in its catalytic efficiency. This protocol can also be applied with other nucleophile reagents to synthesize esters, amides, and acid products.

Synthesis of N-[1-(2-Acetyl-4,5-dimethoxyphenyl)propan-2-yl]benzamide and Its Copper(II) Complex

This paper represents a convenient method for the synthesis of N-[1-(2-acetyl-4,5-dimethoxyphenyl)propan-2-yl]benzamide and its Cu(II) complex. In silico analysis predicted spasmolytic activity for the compound. Based on the in silico calculations, the importance of the predicted ketoamide, and our previous experiments, we synthesized the ketoamide via ortho-acylation of N-[1-(3,4-dimethoxyphenyl)propan-2-yl]benzamide with acetic anhydride in polyphosphoric acid. We applied the title ketoamide in reaction with Cu(II) varying the solvents. We found that the reaction leads to the formation of a coordination compound when the ligand dissolved in DMSO reacts with a water solution of CuCl₂ in an alkaline environment in a molar ratio M : L : OH^- = 1 : 2 : 2. The structures of the new compounds are discussed based on their melting points, IR, ¹H, ¹³C NMR and Raman spectral data.

Alkali-modified heterogeneous Pd-catalyzed synthesis of acids, amides and esters from aryl halides using formic acid as the CO precursor

To establish an environmentally friendly green chemical process, we minimized and resolved a significant proportion of waste and hazards associated with conventional organic acids and molecular gases, such as carbon monoxide (CO). Herein, we report a facile and milder reaction procedure, using low temperatures/pressures and shorter reaction time for the carboxyl- and carbonylation of diverse arrays of aryl halides over a newly developed cationic Lewis-acid promoted Pd/Co3O4 catalyst. Furthermore, the reaction proceeded in the absence of acid co-catalysts, and anhydrides for CO release. Catalyst reusability was achieved via scalable, safer, and practical reactions that provided moderate to high yields, paving the way for developing a novel environmentally benign method for synthesizing carboxylic acids, amides, and esters.

Biogenic synthesis of Pd-nanoparticles using Areca Nut Husk Extract: a greener approach to access α-keto imides and stilbenes

An eco-friendly green method for a one-step synthesis of palladium nanoparticles and their synthetic utility are reported.

POP-Pd(ii) catalyzed easy and safe in situ carbonylation towards the synthesis of α-ketoamides from secondary cyclic amines utilizing CHCl3 as a carbon monoxide surrogate

POP-palladium(ii) was synthesized for the in situ carbonylation of aryl iodides and secondary cyclic amine to the respective α-ketoamides.

Mono- and double carbonylation of aryl iodides with amine nucleophiles in the presence of recyclable palladium catalysts immobilised on a supported dicationic ionic liquid phase

Silica modified with organic dicationic moieties proved to be an excellent support for palladium catalysts used in the aminocarbonylation of aryl iodides.

Facile TEMPO Immobilization onto Poly(acrylic acid)-Modified Magnetic Nanoparticles: Preparation and Property

Adding catalysts to magnetic polyvalent supports facilitating catalyst recycling and recovery seems feasible. Polymer-modified magnetic nanocomposites for organocatalyst immobilization are a plausible approach to this technology. Here, we present facile and efficient method for 2,2′,6,6′-tetramethylpiperidinyl-1-oxy (TEMPO) immobilization onto polymer-modified magnetic nanoparticles under mild reaction conditions. Poly(acrylic acid) was chosen to graft from magnetic nanoparticle through a simple inverse emulsion polymerization technique. The resulting poly(acrylic acid) magnetic nanocomposite is an ideal material to immobilize the organocatalyst 4-hydroxy-2,2′,6,6′-tetramethylpiperidinyl-1-oxy (H-TEMPO) via an esterification reaction with pendant carboxyl group on the polymer chain. Instrumental analysis confirmed that poly(acrylic acid) chain was grafted on the silica-coated magnetic particles by this simple method while maintaining their magnetic properties; elemental analysis indicated that TEMPO was efficiently immobilized onto the polymer chain. The catalysis tests under both Anelli and Minisci system showed that the nanocomposite catalyst exhibits proper selectivity and activity for the alcohol/aldehyde transformation. Recycling experiments showed that stability and reusability of the nanocomposite catalyst were satisfying.

Covalent triazine framework-supported palladium as a ligand-free catalyst for the selective double carbonylation of aryl iodides under ambient pressure of CO

Carbonylation of aryl iodides with amines under atmospheric pressure of CO, catalyzed by Pd/CTFs (covalent triazine frameworks) without any specific additives, leads to the highly selective synthesis of α-ketoamides.

Spontaneous Oxygenation of Siloxy-N-silylketenimines to α-Ketoamides

Siloxy-N-silylketenimines generated in situ from O-silyl cyanohydrins were converted to α-ketoamides by brief exposure to air or oxygen. Oxidation under extremely mild conditions can be explained by assuming the intermediacy of a 3-imino-1,2-dioxetane derivative generated via triplet-singlet intersystem crossing after the reaction of siloxy-N-silylketenimines with triplet oxygen.

Solvent-free aminocarbonylation of iodobenzene in the presence of SILP-palladium catalysts

The recyclable palladium catalysts were used for selective mono- or double carbonylation under solvent-free conditions and in DMF, respectively.

Palladium-catalyzed carbonylation of aryl halides: an efficient, heterogeneous and phosphine-free catalytic system for aminocarbonylation and alkoxycarbonylation employing Mo(CO)6 as a solid carbon monoxide source

Preparation and characterization of palladium nanoparticles immobilized on magnetic methionine-functionalized chitosan as a highly efficient, air stable, and readily reusable heterogeneous catalyst in carbonylation reactions.

Silica supported palladium-phosphine as a reusable catalyst for alkoxycarbonylation and aminocarbonylation of aryl and heteroaryl iodides

Novel, simple, stable and reusable silica-supported palladium phosphine complexes were prepared and found to be highly efficient for the carbonylation of unprotected hydroxy, amino, iodoindole and iodopyrazole under optimized conditions.

Polymer supported Pd catalyzed thioester synthesis via carbonylation of aryl halides under phosphine free conditions

A new polymer anchored Pd(ii) complex has been synthesized and characterized. The catalytic performance of this complex has been tested for thioester synthesis via carbonylation of aryl halides and thiols under phosphine free conditions. This catalyst showed excellent catalytic activity and recyclability.

Mesoporous poly-melamine-formaldehyde stabilized palladium nanoparticle (Pd@mPMF) catalyzed mono and double carbonylation of aryl halides with amines

A new mesoporous polymer stabilized Pd nano (mPMF–Pd⁰) has been synthesized and well characterized. The catalytic performance of this complex has been tested for mono and double carbonylation of aryl halides with amines.

Polymer supported Pd catalyzed carbonylation of aryl bromides for the synthesis of aryl esters and amides

A new polymer anchored Pd(ii) Schiff base catalyst has been synthesized for the evaluation of alkoxycarbonylation and aminocarbonylation reactions of various substituted aryl bromides with alcohols and amines.

Heterogeneous Pd catalysts supported on silica matrices

Features, advantages and limitations associated with palladium catalysts deposited over various siliceous supports in different types of practically useful organic transformations are reviewed.