A neat palladium-catalyzed alkynylation reaction was developed with "super-active ester" as the carbonyl electrophile, which provides a clean and efficient synthetic protocol for a broad array of ynone compounds under CO-, Cu-, ligand-, and base-free conditions. The superior activity of triazine ester was rationalized by the strong electron-withdrawing ability and the unique affinity of triazine on palladium. A mechanistic experiment clearly demonstrated that the N-Pd coordination of triazine plays a crucial role for the highly efficient C-O activation.

A simple and efficient system was developed for the ligand‐free Pd‐catalyzed Suzuki–Miyaura reaction in water under mild conditions. Quaternary ammonium hydroxides with long chains were found to be very suitable bases. This ligand‐free Pd‐catalyzed Suzuki–Miyaura reaction showed improved durability in water with Pd loadings decreased to ppm level. Bases were shown to stabilize active palladium species in addition to acting as a base during the catalytic process. In the catalytic system with a strong base, the soluble active PdII ion exhibited anti‐reduction properties, which prevented aggregation and deactivation of Pd species. The entire catalytic system could be recycled after separating the product by simple filtration. The water‐compatible and air‐stable effective catalytic protocol described herein represents an attractive and green synthetic advance in Suzuki–Miyaura couplings.

A binary acid system has been developed that features an air-stable organometallic precursor, titanocene dichloride, and simple organic cooperative Brønsted acids, which allowed for mild and highly efficient Mannich reactions of both aryl and alkyl ketones with excellent yields and satisfactory diastereoselectivity. Mechanistic studies, including (1) H NMR titration, X-ray structure analyses as well as isolation of catalytically active species, elucidated the dramatic synergistic effects of this new binary acid system.

The position of Pd species in/on zeolites is crucial for the activity of metal/ metal oxide catalysts. It is still a challenge to highly disperse and stabilize the metal species on zeolites and shorten diffusion paths to maintain high catalytic activity. Here, we report an effective strategy for preparing highly efficient zeolite-supported Pd(II) catalysts by positioning Pd(II) species on the surface of a zeolite with an anion framework based on the principle of charge balance. The catalyst was prepared in situ in a C−C cross-coupling reaction. Due to the change in the metal−support interaction, Pd species have migrated from the inside to the surface of the zeolite, which shortens the diffusion path of reactants and thus ensures the high activity of the catalyst. Pd species exhibit aggregation resistance in alkaline systems and tend to be confined in the traps with high charge density. Compared to unactivated Pd@USY, the efficiency of the activated catalysts has at least doubled in catalyzing the Sonogashira and Suzuki−Miyaura reactions. This study represents a new activation approach for zeolite-supported Pd catalysts, which may help to design efficient catalysts.

Neutral ferrocene‐based burning rate (BR) catalysts show strong migration trends and volatility during long‐time storage and curing of the composite solid propellants. To reduce these disadvantages thirty‐two ferrocenyl quaternary ammonium compounds, paired with polycyano anions, were synthesized and characterized by 1H NMR, 13C NMR, and UV/Vis spectroscopy, as well as elemental analysis. Additionally, crystal structures of eight compounds were confirmed by single‐crystal X‐ray diffraction. TG and DSC analyses indicated that the compounds containing 1,1,2,3,3‐pentacyanopropenide anions show high thermal stability. Cyclic voltammetry studies suggested that they are quasi‐reversible or irreversible redox systems. Anti‐migration tests verified that the tested compounds show very low migration tendency and some of them exhibit no migration after 30 days aging at 70 °C. Their catalytic efficiency in the thermal decomposition of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were examined by DSC analyses. The results revealed that most of the compounds exhibit distinct effects on the thermal degradation of AP and RDX. Two compounds have good catalytic ability in the thermal decomposition of HMX, representing rare examples of the reported ferrocenyl ionic compounds, which display catalytic property during combustion of HMX.