Efficient and Practical Synthesis of 3′,4′,5′-Trifluoro-[1,1′-biphenyl]-2-amine: A Key Intermediate of Fluxapyroxad

Photoinduced Deprotection of 2-Nitrophenylneopentyl Glycol Boronates Enables Light-Triggered Polycondensation of Siloxanes

Various protecting groups have been developed for boronic acids, mostly based on diols. Alternatives include trifluoroborates and amine complexes, which offer easier synthesis and release under milder conditions. We present here a new strategy involving photocleavable protecting groups for boronic and borinic acids, based on the 2-nitrobenzyl motif. A screening of several 1,2- and 1,3-diols bearing a 2-nitrobenzyl group led us to identify 1-(2-nitrophenyl)neopentyl glycol (npnp) for the protection of boronic acid derivatives. This diol is easily prepared in a single step on gram scale, and the corresponding npnp boronates are stable in wet acetonitrile at 90 °C for several days, and under under acidic conditions. Irradiation at 365 nm in acetonitrile allows for the controlled liberation of boronic acids in good to excellent yields, a method also applied to a dimesitylborinic ester bearing a 2-nitrobenzylalcohol moiety. 1-(2-Nitrophenyl)neopentyl glycol boronates ArB(npnp) demonstrated their utility in light-triggered siloxane crosslinking. We showed that catalysts incorporated into a polymer matrix, irradiated, and then incubated at 50 °C for 7 days resulted in efficient polymerization, forming solid materials in some cases.

Trace amounts of palladium catalysed the Suzuki-Miyaura reaction of deactivated and hindered aryl chlorides

Electron-rich and hindered aryl chlorides are the most challenging substrates in Suzuki-Miyaura cross-coupling (SMC) reactions. Herein, we report a highly efficient catalytic system for the SMC reaction using trace amounts of commercially available catalysts [Pd(PPh3)4/(t-Bu)PCy2; Pd loading as low as 9.5 × 10-5 mol%]. This catalytic system can efficiently couple deactivated and sterically hindered aryl chlorides with various substituted phenylboronic acids, even in one-pot multiple coupling reactions (yield of products up to 92%). The impact of solvents on SMC reactions and the mechanisms of by-product formation in aryl boronic acid couplings are analyzed using density functional theory (DFT). Utilizing trace amounts of commercially available catalysts avoids complex synthesis, reduces costs, and minimizes metal residues.

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.

Calixarene-supported Pd–NHC complexes as efficient catalysts for scalable Suzuki–Miyaura cross-couplings

Calixarene-supported PEPPSI-catalysts deliver high yielding and almost Pd trace-free Suzuki–Miyaura coupling products.