Free-Amine Directed Arylation of Biaryl-2-amines with Aryl Iodides by Palladium Catalysis

A new palladium-catalyzed free-amine directed arylation of C(sp²)–H bonds in the presence of AgOAc and TFA is described. Biaryl-2-amines react with various aryl iodides to give the corresponding mono- or diarylated products with exclusive regioselectivity

Design for Novel Hot-Work Die Steel by Thermodynamic Calculation and Microstructural Examination

In this paper, a new type of hot-work die steel with excellent high-temperature mechanical properties at 700 °C was designed based on the traditional 25Cr3Mo3NiNb steel with the help of Thermo-calc software. The effects of C, Cr, Mo, W and V on the types and mass fractions of carbides were studied. Phase diagram calculation revealed that with the increase of V and W contents and the decrease of Cr content, the precipitation temperature and the mass fraction of M23C6 carbides decreased. Meanwhile, the mass fraction of MC carbides increased as the Mo content decreased. Based on the thermodynamic calculation, new material 25Cr3Mo2NiWVNb steel was designed. Compared to the 25Cr3Mo3NiNb steel, more finely dispersed MC and M2C carbides with high thermal stability, as well as fewer M23C6 carbides with low thermal stability, were precipitated in the new steel. The high-temperature tensile showed that the new steel showed high thermal stability and strength even at 700 °C. The high-temperature strengthening effect might be ascribed to the fine and stable nano-scale MC and M2C carbides which precipitated during tempering

Copper-Catalyzed Reaction of Ketenimine and in Situ Generated Immonium Ion: Access to α<i>,</i>β‑Unsaturated Amidines

A Cu-catalyzed three-component reaction of alkyne, azides (sulfonyl or phosphoryl azides), and <i><i>N</i></i>,<i><i>N</i></i>-dialkyloxyformamide dialkyl acetal via electrophilic addition of immonium ion to copper ketenimine is reported. This new protocol for the preparation of α,β-unsaturated amidine derivatives appears to offer high yield, mild conditions, and wide substrate scope. The reaction might involve the processes of copper ketenimine intermediate formation, electrophilic addition, and isomerization

Cu(II)-Promoted Palladium-Catalyzed C–H Ortho-Arylation of <i>N</i>,<i>N</i>‑Dimethylbenzylamines

A novel protocol for palladium-catalyzed arylation of the C­(sp²)–H bond directed by a <i>N</i>,<i>N</i>-dimethylaminomethyl group in the presence of AgOAc and Cu­(OAc)₂·H₂O is described. Various aryl iodides proved to be efficient coupling partners, furnishing the corresponding ortho monoarylated or diarylated arenes in moderate to good yields. Cu­(OAc)₂·H₂O is found to be the important additive to improve the yields in this transformation