Recent Advances in the Catalytic Synthesis of α-Ketoamides

α-Ketoamides are privileged chemical entities featuring a carbonyl group bonded to an amide. Bearing two pronucleophilic and two proelectrophilic sites, this structural scaffold exhibits distinct chemical properties and unparalleled biological activity. Owing to its wide application in medicinal, agricultural, and synthetic chemistry, methods for assembling this distinct moiety are ever-growing in demand. With the increasing focus on green synthesis, traditional routes to α-ketoamides have faded in recent years giving rise to the development of photocatalytic, electrosynthetic, and microwave-assisted catalytic protocols. We hereby provide a comprehensive and critical summary of all the catalytic advancements witnessed in this field from 2016 to the present.

Synthesis of α-ketoamides via oxidative amidation of diazo compounds with O-benzoyl hydroxylamines as nitrogen source and the oxidant

A simple, efficient method has been described for the construction of an array of α-ketoamides from readily available O-benzoyl hydroxylamines and diazo compounds as starting materials. There was a combined use of CuI as a catalyst and H2O as the oxygen source. The investigation reveals that the O-benzoyl hydroxylamines serve a dual role as both an amine source and the oxidant in this mechanism, thereby obviating the need for additional oxidants in the transformation process. This methodology could give a wider range of products in good to excellent yields for most substrates, and thus, we provide a new idea for the synthesis of α-ketoamides.

Synthesis of TiO2-Cu2+/CuI Nanocomposites and Evaluation of Antifungal and Cytotoxic Activity

Fungal infections have become a significant public health concern due to their increasing recurrence and harmful effects on plants, animals, and humans. Opportunistic pathogens (among others from the genera Candida and Aspergillus) can be present in indoor air, becoming a risk for people with suppressed immune systems. Engineered nanomaterials are novel alternatives to traditional antifungal therapy. In this work, copper(I) iodide (CuI) and a copper-doped titanium dioxide-copper(I) iodide (TiO₂-Cu²⁺/CuI) composite nanomaterials (NMs)-were synthesized and tested as antifungal agents. The materials were synthesized using sol-gel (TiO₂-Cu²⁺) and co-precipitation (CuI) techniques. The resulting colloids were evaluated as antifungal agents against Candida parapsilosis and Aspergillus niger strains. The NMs were characterized by XRD, HRTEM, AFM, and DLS to evaluate their physicochemical properties. The NMs present a high size dispersion and different geometrical shapes of agglomerates. The antifungal capacity of the NMs by the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) was below 15 µg/mL against Candida parapsilosis and below 600 µg/mL against Aspergillus niger for both NMs. Holotomography microscopy showed that the NMs could penetrate cell membranes causing cell death through its rupture and reactive oxygen species (ROS) production. Cytotoxicity tests showed that NMs could be safe to use at low concentrations. The synthesized nanomaterials could be potential antifungal agents for biomedical or environmental applications.

One-Pot Synthesis of Copper Iodide-Polypyrrole Nanocomposites

A novel one-pot chemical synthesis of functional copper iodide-polypyrrole composites, CuI-PPy, has been proposed. The fabrication process allows the formation of nanodimensional metal salt/polymer hybrid structures in a fully controlled time- and concentration-dependent manner. The impact of certain experimental conditions, viz., duration of synthesis, sequence of component addition and concentrations of the intact reagents on the structure, dimensionality and yield of the end-product was evaluated in detail. More specifically, the amount of marshite CuI within the hybrid composite can be ranged from 60 to 90 wt.%, depending on synthetic conditions (type and concentration of components, process duration). In addition, the conditions allowing the synthesis of nano-sized CuI distributed inside the polypyrrole matrix were found. A high morphological stability and reproducibility of the synthesized nanodimensional metal-polymer hybrid materials were approved. Finally, the electrochemical activity of the formed composites was verified by cyclic voltammetry studies. The stability of CuI-PPy composite deposited on the electrodes was strongly affected by the applied anodic limit. The proposed one-pot synthesis of the hybrid nanodimensional copper iodide-polypyrrole composites is highly innovative, meets the requirements of Green Chemistry and is potentially useful for future biosensor development. In addition, this study is expected to generally contribute to the knowledge on the hybrid nano-based composites with tailored properties.

High yield and greener C–H difluoromethylation reactions using copper iodide nanoparticles/boron nitride nanosheets as a versatile and recyclable heterogeneous catalyst

The 3 wt% CuI/BNNS catalyst exhibited high efficiency for C–H difluoromethylation reactions and enabled greener synthesis at high yields using cyrene as a solvent. Furthermore, the catalyst could be easily recovered and recycled for at least five cycles.

Selective synthesis of aryl thioamides and aryl-α-ketoamides from α-oxocarboxylic acids and tetraalkylthiuram disulfides: an unexpected chemoselectivity from aryl sulfonyl chlorides

Tosyl chloride-controlled generation of thioamides and α-ketoamides via base-promoted decarboxylative reaction of α-oxocarboxylic acids with tetraalkylthiuram disulfides has been established.