A Sustainable 1-Pot, 3-Step Synthesis of Boscalid Using Part per Million Level Pd Catalysis in Water

Photocatalytic Synthesis of Diaryl Amides via Direct Coupling of Methyl Arenes and Nitroarenes

A direct and effective method for synthesizing diaryl amides has been developed through the photocatalytic coupling of methyl and nitroarenes. This method employs FeCl3 as a redox-active photocatalyst under mild conditions to enable selective benzylic C-H activation and concurrent nitro group reduction, eliminating the necessity for pre-functionalization. This method exhibits a broad substrate scope, high functional group tolerance, and improved atom economy, offering a sustainable and practical alternative to amide bond formation.

Organocatalytic [4+2] Benzannulation Between 1,4-Dithiane-Based Enal and Nitroolefins to Access 2-Nitrobiaryls

A simple method for constructing unsymmetrical 2-nitrobiaryls has been developed between substituted 1,4-dithiine-2-carbaldehyde and nitroolefins under metal-free conditions. To gain the advantage of the HOMO-raising effect of temporary substitutions on in situ generated dienamine intermediate, the present protocol established [4+2] benzannulation of 1,4-dithiane-tethered enals with nitroolefin. Further, easy unmasking of 1,4-dithiine units results in a benzannulation product like that of unsubstituted enals, which are difficult to access. Several 2-nitrobiaryls have been accessed with moderate to good yields and with promising synthetic applications.

CuI-Zeolite Catalysis for Biaryl Synthesis via Homocoupling Reactions of Phenols or Aryl Boronic Acids

Due to the importance of biaryls as natural products, drugs, agrochemicals, dyes, or organic electronic materials, a green alternative biaryl synthesis has been developed based on easy-to-prepare and cheap copper(I)-exchanged zeolite catalysts. CuI-USY proved to efficiently catalyze the direct homocoupling of either phenols or aryl boronic acids under simple and practical conditions. The CuI-USY-catalyzed oxidative homocoupling of phenols could conveniently be performed under air either in warm methanol or water with good to high yields. In methanol, a small amount of Cs2CO3 was required, while none was necessary in water. The homocoupling of aryl boronic acids was best performed also in warm methanol, without an additive. These mild conditions showed good functional-group tolerance, leading to a variety of substituted (hetero)biaryls (28 examples). The heterogeneous CuI-USY catalyst could readily be recovered and reused. Interestingly, the homocoupling of vinyl boronic acids was successfully coupled to a Diels-Alder reaction, even in a one-pot process, allowing access to highly functionalized cyclohexenes.

Diastereoselective Hydrodifluoromethylation of Alkenyl N-Heterocycles via Photocatalytic Radical-Polar Crossover

A diastereoselective hydrodifluoromethylation of N-heteroaryl alkenes was successfully established. This method was applicable to an array of N-heteroaryl substrates with both cyclic and acyclic alkenes while displaying tolerance to a variety of functional groups. The conditions were also expanded to obtain hydrotrifluoromethylated products with similar results. Initial mechanistic studies suggest that the final protonation step is accessed through a radical-polar crossover process.

The Substituent Effects of Suzuki Coupling in Aqueous Micelles

The Suzuki coupling in aqueous micelles has received much attention, but few attempts focus on its substituent effects. In view of the significant substituent effects on this reaction, it is necessary and practical to investigate its substituent effects. Herein, the substituent effects of Suzuki coupling in aqueous micelles are well established through Hammett plots and kinetic studies. In the cases of aryl halides, the rate-determining step of the reaction will shift from the oxidation addition step to the transmetalation step as the substituents' electron withdrawing ability increases, so aryl halides with weak electron-withdrawing groups exhibit better reactivity than ones containing strong electron-withdrawing or electron-donating groups. For arylboronic acids, the electron donating groups are beneficial to the Suzuki reaction, while the electron withdrawing group is unfavorable for the reaction. The Suzuki reactions of substituent exchange between arylboronic acids and aryl halides further confirm these substituent effects.

Design and Discovery of Water-Soluble Benzooxaphosphole-Based Ligands for Hindered Suzuki-Miyaura Coupling Reactions with Low Catalyst Load

We report a new class of highly effective, benzooxaphosphole-based, water-soluble ligands in the application of Suzuki-Miyaura cross-coupling reactions for sterically hindered substrates in aqueous media. The catalytic activities of the coupling reactions were greatly enhanced by the addition of catalytic amounts of organic phase transfer reagents, such as tetraglyme and tetrabutylammonium bromide. The optimized general protocol can be conducted with a low catalyst load, thereby providing a practical solution for these reactions. The viability of this new Suzuki-Miyaura protocol was demonstrated with various substrates to generate important building blocks, including heterocycles, for the synthesis of biologically active compounds.

Introducing Savie: A Biodegradable Surfactant Enabling Chemo- and Biocatalysis and Related Reactions in Recyclable Water

Savie is a biodegradable surfactant derived from vitamin E and polysarcosine (PSar) developed for use in organic synthesis in recyclable water. This includes homogeneous catalysis (including examples employing only ppm levels of catalyst), heterogeneous catalysis, and biocatalytic transformations, including a multistep chemoenzymatic sequence. Use of Savie frequently leads to significantly higher yields than do conventional surfactants, while obviating the need for waste-generating organic solvents.

Cascade Processes with Micellar Reaction Media: Recent Advances and Future Directions

Reducing the use of solvents is an important aim of green chemistry. Using micelles self-assembled from amphiphilic molecules dispersed in water (considered a green solvent) has facilitated reactions of organic compounds. When performing reactions in micelles, the hydrophobic effect can considerably accelerate apparent reaction rates, as well as enhance selectivity. Here, we review micellar reaction media and their potential role in sustainable chemical production. The focus of this review is applications of engineered amphiphilic systems for reactions (surface-active ionic liquids, designer surfactants, and block copolymers) as reaction media. Micelles are a versatile platform for performing a large array of organic chemistries using water as the bulk solvent. Building on this foundation, synthetic sequences combining several reaction steps in one pot have been developed. Telescoping multiple reactions can reduce solvent waste by limiting the volume of solvents, as well as eliminating purification processes. Thus, in particular, we review recent advances in “one-pot” multistep reactions achieved using micellar reaction media with potential applications in medicinal chemistry and agrochemistry. Photocatalyzed reactions in micellar reaction media are also discussed. In addition to the use of micelles, we emphasize the process (steps to isolate the product and reuse the catalyst).

The research progress in and perspective of potential fungicides: Succinate dehydrogenase inhibitors

Succinate dehydrogenase inhibitors (SDHIs) have become one of the fastest growing classes of new fungicides since entering the market, and have attracted increasing attention as a result of their unique structure, high activity and broad fungicidal spectrum. The mechanism of SDHIs is to inhibit the activity of succinate dehydrogenase, thereby affecting mitochondrial respiration and ultimately killing pathogenic fungi. At present, they have become popular varieties researched and developed by major pesticide companies in the world. In the review, we focused on the mechanism, the history, the representative varieties, structure-activity relationship and resistance of SDHIs. Finally, the potential directions for the development of SDHIs were discussed. It is hoped that this review can strengthen the individuals' understanding of SDHIs and provide some inspiration for the development of new fungicides.

Direct Arylation in the Presence of Palladium Pincer Complexes

Direct arylation is an atom-economical alternative to more established procedures such as Stille, Suzuki or Negishi arylation reactions. In comparison with other palladium sources and ligands, the use of palladium pincer complexes as catalysts or pre-catalysts for direct arylation has resulted in improved efficiency, higher reaction yields, and advantageous reaction conditions. In addition to a revision of the literature concerning intra- and intermolecular direct arylation reactions performed in the presence of palladium pincer complexes, the role of these remarkably active catalysts will also be discussed.

Synthesis, Crystal Structure, Herbicidal Activity, and SAR Study of Novel N-(Arylmethoxy)-2-chloronicotinamides Derived from Nicotinic Acid

Nicotinic acid, also known as niacin, is a natural product, which is widely found in plants and animals. To discover novel natural-product-based herbicides, a series of N-(arylmethoxy)-2-chloronicotinamides were designed and synthesized. Some of the new N-(arylmethoxy)-2-chloronicotinamides exhibited excellent herbicidal activity against Agrostis stolonifera (bentgrass) at 100 μM. Compound 5f (2-chloro-N-((3,4-dichlorobenzyl)oxy)nicotinamide) possessed excellent herbicidal activity against Lemna paucicostata (duckweed), with an IC₅₀ value of 7.8 μM, whereas the commercial herbicides clomazone and propanil had values of 125 and 2 μM, respectively. The structure-activity relationships reported in this paper could be used for the development of new herbicides against monocotyledonous weeds.

Mild and Robust Stille Reactions in Water using Parts Per Million Levels of a Triphenylphosphine-Based Palladacycle

An inexpensive and new triphenylphosphine-based palladacycle has been developed as a pre-catalyst, leading to highly effective Stille cross-coupling reactions in water under mild reaction conditions. Only 500-1000 ppm of Pd suffices for couplings involving a variety of aryl/heteroaryl halides with aryl/hetaryl stannanes. Several drug intermediates can be prepared using this catalyst in aqueous nanoreactors formed by 2 wt % Brij-30 in water.

Recent advances on micellar catalysis in water

Water is the universal solvent in nature to catalyze the biological transformation processes. However, owing to the immiscibility of many reagents in water, synthesis chemistry relies heavily on organic solvent. Micellar media is a green alternative to traditional petroleum feedstock derived solvents, which is recently attracting increasing research attention. The present review deals with the recent advances in micellar catalysis with an emphasis on the new "tailor-made" surfactants for various reactions. A brief overview of commercial surfactants, including anionic micelles, cationic micelles, and nonionic micelles is presented. More importantly, an attempt was made to discuss systematically the recent research progress on new surfactants by introducing structures, micellar effects and recycling process, aiming to serve as the basis for future development of surfactants.

Sustainable and Cost-Effective Suzuki-Miyaura Couplings toward the Key Biaryl Subunits of Arylex and Rinskor Active

Challenging Suzuki-Miyaura cross couplings associated with novel crop protection active ingredients from Corteva Agriscience, Arylex and Rinskor, can be performed in water using parts per million (ppm) levels of a Pd catalyst. Each coupling required a distinct set of reaction conditions to achieve maximum selectivities and chemical yields. By way of comparison, this chemistry is not only performed under environmentally responsible aqueous micellar conditions, but also involves lowering loadings (3-5 times) of endangered palladium than used previously to attain a more sustainable process.

Discovery, Synthesis, and Scale-up of Efficient Palladium Catalysts Useful for the Modification of Nucleosides and Heteroarenes

Nucleic acid derivatives are imperative biomolecules and are involved in life governing processes. The chemical modification of nucleic acid is a fascinating area for researchers due to the potential activity exhibited as antiviral and antitumor agents. In addition, these molecules are also of interest toward conducting useful biochemical, pharmaceutical, and mutagenic study. For accessing such synthetically useful structures and features, transition-metal catalyzed processes have been proven over the years to be an excellent tool for carrying out the various transformations with ease and under mild reaction conditions. Amidst various transition-metal catalyzed processes available for nucleoside modification, Pd-catalyzed cross-coupling reactions have proven to be perhaps the most efficient, successful, and broadly applicable reactions in both academia and industry. Pd-catalyzed C-C and C-heteroatom bond forming reactions have been widely used for the modification of the heterocyclic moiety in the nucleosides, although a single catalyst system that could address all the different requirements for nucleoside modifications isvery rare or non-existent. With this in mind, we present herein a review showcasing the recent developments and improvements from our research groups toward the development of Pd-catalyzed strategies including drug synthesis using a single efficient catalyst system for the modification of nucleosides and other heterocycles. The review also highlights the improvement in conditions or the yield of various bio-active nucleosides or commercial drugs possessing the nucleoside structural core. Scale ups wherever performed (up to 100 g) of molecules of commercial importance have also been disclosed.

Recent designer surfactants for catalysis in water

Recent development of new designer surfactants further spurs the development of micellar catalysis in water for chemical transformations and catalysis, providing reliable alternatives to the employment of organic solvents.