Preparation and characterization of self-healing furan-terminated polybutadiene (FTPB) based on Diels-Alder reaction.

Cracks generated in energetic composites will affect their mechanical properties and increase the risk of explosion when they are exposed to external stimuli. Therefore, self-healing properties of energetic composites have always been at the forefront of research in the field of high-performance energetic composites. Hydroxyl-terminated polybutadiene (HTPB) is a kind of binder widely used in propellants. A novel furan-terminated polybutadiene (FTPB) was synthesized by the reaction of NCO-terminated polybutadiene (IPDI-HTPB-IPDI) with furfuryl amine, and then self-healing binder films were obtained based on the DA adduct (FTPB-DA) through the reaction of furan with bismaleimide. The results show that FTPB-DA will transform into FTPB and BMI at 120 °C and recrosslinked at 60 °C to form FTPB-DA again, which gives it self-healing properties and the healing efficiency can reach 92.3%. Then, by adjusting the ratio of -NCO/-OH during the preparation process, we prepared self-healing binders with different DA adduct contents, and further studied the influence of DA adduct content on the mechanical properties and self-healing performance.

Ruthenium-catalyzed remote C5-sulfonation of N-alkyl-8-aminoquinolines.

There is an increasing demand for the methodologies of positionally selective remote C-H functionalizations. We herein report the ruthenium-catalyzed remote C5-selective sulfonation of 8-aminoquinoline derivatives. Moderate to high yields were obtained with different substituted substrates. The catalytic system exhibited a high regio-selectivity, as well as good functional group tolerance. Mechanistic study supported a radical pathway. A bifunctional ruthenium-catalytic cycle is proposed.

Nickel(0)-Catalyzed Inert C-O Bond Functionalization: Organo Rare-Earth Metal Complex as the Coupling Partner.

An organo rare-earth metal complex has been employed as a highly efficient nucleophile in Ni(0)-catalyzed C-O bond functionalization. The optimized catalytic system which consists of Ni(cod)2, PCy3, and t-BuONa could smoothly convert 1 equiv of naphthyl ethers to alkylated naphthalene analogues with 0.4 equiv of Ln(CH2SiMe3)3(THF)2, delivering good to excellent yields. The reaction system could also activate the ArCH2-O bond with mild base.

C-H arylations of 1,2,3-triazoles by reusable heterogeneous palladium catalysts in biomass-derived γ-valerolactone.

C-H arylations were accomplished with a user-friendly heterogeneous palladium catalyst in the biomass-derived γ-valerolactone (GVL) as an environmentally-benign reaction medium. The user-friendly protocol was characterized by ample substrate scope and high functional group tolerance in the C-H arylation of 1,2,3-triazoles, and the palladium catalyst could be recycled and reused in the C-H activation process.

Photoinduced Copper-Catalyzed C-H Arylation at Room Temperature.

Room-temperature azole C-H arylations were accomplished with inexpensive copper(I) compounds by means of photoinduced catalysis. The expedient copper catalysis set the stage for site-selective C-H arylations of non-aromatic oxazolines under mild reaction conditions, and provides step-economical access to the alkaloid natural products balsoxin and texamine.

Dehydrative C-H/N-OH functionalizations in H2O by ruthenium(II) catalysis: subtle effect of carboxylate ligands and mechanistic insight.

A ruthenium(II) complex derived from the electron-deficient aromatic carboxylic acid 3-(F3C)C6H4CO2H proved to be a highly efficient catalyst for dehydrative alkyne annulation by NH-free hydroxamic acids in water. The C-H/N-OH functionalization occurred with excellent positional selectivity as well as ample substrate scope, setting the stage for effective intermolecular alkenylations of hydroxamic acids. Detailed mechanistic studies were suggestive of a kinetically relevant C-H metalation by carboxylate assistance along with subsequent migratory alkyne insertion, reductive elimination, and intramolecular oxidative addition.

Aldehyde-assisted ruthenium(II)-catalyzed C-H oxygenations.

Versatile ruthenium(II) complexes allow for site-selective C-H oxygenations with weakly-coordinating aldehydes. The challenging C-H functionalizations proceed with high chemoselectivity by rate-determining C-H metalation. The new method features an ample substrate scope, which sets the stage for the step-economical preparation of various bioactive heterocycles.

Ruthenium-catalyzed C-H oxygenation on aryl Weinreb amides.

Versatile ruthenium catalysts enabled unprecedented C-H bond oxygenations of aryl Weinreb amides with ample scope under exceedingly mild reaction conditions, thereby also giving access to valuable ortho-hydroxylated aldehydes. Mechanistic studies provided strong support for a kinetically relevant C-H bond activation.

Enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone: a flexible approach to chiral gamma-butyrolactones.

The enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone has been achieved without using any protecting groups. The synthesis involved using an asymmetric alkynylation to obtain gamma-hydroxy-alpha,beta-acetylenic esters with high ee (84%) and yields ( approximately 80%), followed by selective hydrogenation and lactonization in high overall yields (87% and 89%).