Kryptofix 5 as an inexpensive and efficient ligand for the palladium-catalyzed Mizoroki-Heck reaction

Synthesis of 3-Carbonyl Trisubstituted Furans via Pd-Catalyzed Aerobic Cycloisomerization Reaction: Development and Mechanistic Studies

Herein, we report the synthesis of 3-carbonyl-trisubstituted furans via Pd-catalyzed oxidative cycloisomerization reactions of 2-alkenyl-1,3-dicarbonyl scaffolds, using molecular oxygen as the sole oxidant to regenerate active palladium catalytic species, featuring good functional tolerance and mild reaction conditions. Deep investigation of intermediates and transition states of the reaction mechanism were conducted via experimental and DFT studies, providing a detailed mechanistical profile. The new developed methodology presents a greener alternative to Wacker-type cycloisomerizations and avoids the use of stoichiometric amounts of oxidants and strong acid additives.

Synthesis of nano magnetic supported NHC-palladium and investigation of its applications as a catalyst in the Mizoroki-Heck cross-coupling reaction in H2O

The unique properties of N-heterocyclic carbenes (NHCs) as an effective ligand for palladium catalytic centers have recently found much attention. In this work, Fe₃O₄ nanoparticle supported palladium(II)-N-heterocyclic carbene catalyst was successfully designed, synthesized and characterized by various methods. The activity of the catalyst was evaluated in the Mizoroki-Heck cross-coupling reaction in which the desired products were obtained in high yield in H₂O as a green solvent. The reaction was carried out in short reaction times using low amounts of the catalyst. Moreover, the catalyst was easily separated from the reaction media and reused for 5 cycles.

A nickel nanoparticle engineered CoFe2O4@GO-Kryptofix 22 composite: a green and retrievable catalytic system for the synthesis of 1,4-benzodiazepines in water

A composite of Ni nanoparticles incorporated in Kryptofix 22 conjugated magnetic nano-graphene oxide, CoFe2O4@GO-K 22·Ni, was synthesized via the grafting of Kryptofix 22 moieties on the magnetic nano-graphene oxide surface, followed by reaction of the nanocomposite with nickel nitrate. The Kryptofix 22 host material unit cavities can stabilize the Ni nanoparticles effectively and prevent their aggregation and separation from the surface. Characterization of the catalysts by FT-IR, FE-SEM, TGA, ICP, EDX, XRD, VSM and BET aided understanding the catalyst structure and morphology. This catalyst was efficiently applied for the synthesis of 1,4-benzodiazepine derivatives. The main advantages of the method are mild reaction conditions, inexpensive catalyst, it is environmentally benign, has high to excellent yields and shorter reaction times. This organometallic catalyst can be easily separated from a reaction mixture and was successfully examined for six runs with a slight loss of catalytic activity.

Base Metal-Catalyzed Direct Olefinations of Alcohols with Sulfones

Herein, a base-metal nickel-catalyzed direct olefination of alcohols with sulfones is reported. The reaction operates under low catalyst loading and does not require an external redox reagent. A wide range of trans-stilbenes and styrenes were synthesized in good yields and selectivities. Biologically active stilbene DMU-212 could also be synthesized in a single step under these conditions. Mechanistic studies involving kinetic isotope effect, deuterium labeling experiments, and catalytic and stoichiometric reactions with possible catalytic intermediates were performed to elucidate a plausible mechanism.