A mild, efficient electrochemical approach to the site-selective direct C–H amidation of benzene and its derivatives with acetonitrile and benzonitrile has been developed. It has been shown that joint electrochemical oxidation of various arenes in the presence of a copper salt as a catalyst and nitriles leads to the formation of N-phenylacetamide from benzene and N-benzylacetamides from benzyl derivatives (up to 78% yield). A favorable feature of the process is mild conditions (room temperature, ambient pressure, no strong oxidants) that meet the criteria of green chemistry.

Acetonitrile and benzonitrile as versatile amino sources in copper-catalyzed mild electrochemical C–H amidation reactions

Cyclic diaryliodoniums are an important class of high-valent aromatic iodine reagents for the synthesis of various axially chiral biaryls and biaryl compounds. Moreover, transition-metal-catalyzed annulation has been established for the construction of various heterocyclic rings and ladder-type π-conjugated polycyclic aromatic hydrocarbons with readily available cyclic diaryliodoniums as the starting materials. As halogen-bonding donors, cyclic aryliodoniums have been explored as organocatalysts in a variety of organic reactions. In this review, the application progress of cyclic diaryliodoniums has been systematically outlined, which highlights recent developments in the application reactions of cyclic diaryliodoniums, including synthetic application, limitations and reaction mechanisms in representative cascade reactions to provide insights for the development prospects of cyclic diaryliodoniums. 

Cyclic Diaryliodonium Salts: Eco‐Friendly and Versatile Building Blocks for Organic Synthesis

Amino Acids in Electrochemical Metal-Free Benzylic C-H Amidation

Nitrilases and nitrile hydratases/amidases hydrolyze nitriles into carboxylic acids and/or amides, which are used in industrial chemical processes. In the present study, 26 microorganisms, including yeasts and filamentous fungi, in a minimum solid mineral medium supplemented with glucose and phenylacetonitrile were screened to evaluate their biocatalytic potential. Of these microorganisms, five fungi of the genus Aspergillus were selected and subjected to colorimetry studies to evaluate the production and distinction of nitrilase and nitrile hydratase/amidase enzymes. Aspergillus parasiticus Speare 7967 and A. niger Tiegh. 8285 produced nitrilases and nitrile hydratase, respectively. Nitrilase optimization was performed using a Box-Behnken design (BBD) and fungus A. parasiticus Speare 7967 with phenylacetonitrile volume (μl), pH, and carbohydrate source (starch:glucose; g/g) as independent variables and nitrilase activity (U ml-1 ) as dependent variable. Maximum activity (2.97 × 10-3  U ml-1 ) was obtained at pH 5.5, 80 μl of phenylacetonitrile, and 15 g of glucose. A. parasiticus Speare 7967 showed promise in the biotransformation of nitriles to carboxylic acids.

High-throughput screening for distinguishing nitrilases from nitrile hydratases in Aspergillus and application of a Box-Behnken design for the optimization of nitrilase.

Lichao Zhou

Papers

Ligand-free copper-catalyzed direct amidation of diaryliodonium salts using nitriles as amidation reagents