Olefin Epoxidation with a New Class of Ansa‐Molybdenum Catalysts in Ionic Liquids

Synthesis and characterization of novel cyclopentadienyl molybdenum imidazo[1,5-a]pyridine-3-ylidene complexes and their application in olefin epoxidation catalysis

“…As far as we are aware, only ansa-cyclopentadienyl molybdenum complexes in RTIL [18] exceed the activity of the reported pre-catalyst 1 in terms of TOF. Catalytic investigations of 2 show even higher activities with TOFs up to 53,100 h À1 at a pre-catalyst loading of 0.01 mol%.…”

“…The upper phase consists of substrate and n-decane, while the lower phase contains RTIL plus catalyst; TBHP is partially soluble in both phases. Taking into account the advantages of RTILs such as low volatility, thermal stability, high polarity, simple catalyst recycling, and product separation [18,86], the prolonged reaction times are acceptable for potential applications, especially considering the obtained high conversion.…”

“…Of these, the ansa-bridged cyclopentadienyl Mo complex [{g 5 -C 5 H 4 [CH(CH 2 ) 3 ]-g 1 -CH}Mo(CO) 3 ] [16] shows the highest TOF in ciscyclooctene epoxidation, namely 11,800 h À1 in organic solvents [17] and TOFs up to 44,000 h À1 in room temperature ionic liquids (RTILs) [18].…”

Molecular Epoxidation Reactions Catalyzed by Rhenium, Molybdenum, and Iron Complexes

“…When using the ionic liquid [C 4 mim][NTf 2 ] (C 4 mim = 1‐butyl‐3‐methylimidazolium) as the solvent, it was possible to obtain TOFs of up to 44000 h −1 (with catalyst 2k for cyclooctene epoxidation) exceeding even MTO. It was also possible to epoxidize a variety of other olefins in excellent yields . They were originally synthesized in the hope to introduce a stereo‐center next to the molybdenum atom and to restrict the flexibility of the Cp ring system (if a chiral group was attached to it).…”

Low‐Valent Molybdenum‐Based Dual Pre‐Catalysts for Highly Efficient Catalytic Epoxidation of Alkenes and Deoxygenation of Sulfoxides

“…[31] Furthermore, by using ionic liquids, the activity of the complexes increases, resulting in TOFs above 8000 h À1 for [MoO 2 X 2 L 2 ] [30] and up to extraordinary 44 000 h À1 for the ansa-complex. [32] Another molybdenum-catalyzed reaction of interest is the bio-inspired deoxygenation of diorganosulfoxides to the corresponding thioethers (sulfides), which is, as mentioned above, performed in nature by molybdenum-based enzymes of the dimethyl sulfoxide reductase family. As they represent excellent free radical scavengers, they are intensively discussed as being an important factor in the biochemistry of the human body, which highlights the attractiveness of these catalytic transformations for drug synthesis and other medical applications.…”