Mild, Selective Sulfoxidation with Molybdenum(VI) cis-Dioxo Catalysts

Abstract

Three molybdenum(VI) cis -dioxo catalysts ( 8 – 10 ) were synthesized with the goal of developing stable and selective oxidation catalysts for sulfoxidation. Their reactivities were investigated with a variety of substrates. We have demonstrated the usefulness of these catalysts for the chemoselective sulfoxidation of sulfides in the presence of reactive moieties, which has important applications for total synthesis processes. Notably, these catalysts are able to oxidize compounds analogous to sulfur mustard and can be used as an alternative to sodium periodate or meta -chloroperoxybenzoic acid ( m -CPBA) for the oxidation of various organic sulfides without sacrificing total conversion. As the catalysts are tolerant of water and hydrogen peroxide, they allow for the design of completely green oxidation reactions, particularly for sulfur-containing amino acids.

Hydrazone‐Based Ligand with Pyrrolidine Donor and Its Molybdenum(VI) Complex: Synthesis, Structure, and Reactivity

“…In the presence of 1 mol % of complex in a dichlormethane methanol solution mixture an overall yield of 83 % was observed after a reaction time of 18 h, with the sulfoxide being the major product, which is well within the reported range observed for other molybdenum(VI) catalysts. [11,16,31] Unfortunately, the reaction also leads to an overoxidation resulting in the corresponding sulfone at an amount of 25 % of the final product. Although this is a feature commonly observed for molybdenum(VI) catalysts, it is worth noting that no such overoxidation is observed for molybdenum(VI) and vanadium(V) catalysts with related Nsalicylidene hydrazide ligands.…”

“…[10] However, the number of documented cis-dioxomolybdenum(VI) complexes catalyzing the peroxidic oxidation of sulfides is still rather limited. [11] Hydrazones are widely used ligand systems due to their potential in various fields including analytical, sensing, switching, and biological applications. [12] A specific subgroup of interest in medicinal and coordination chemistry are the acylhydrazones, [13] which in the case of their salicylidene derivatives are tridentate chelate ligands.…”

Flow Electrosynthesis of Sulfoxides, Sulfones, and Sulfoximines without Supporting Electrolytes

“…Many variations of the organosulfur oxidation process have been developed to generate more viable and long-lasting oxidative procedures that will have an impact on the pharmaceutical industry to reduce cost, waste, and byproducts. Generally, such oxidation processes can be performed using different oxidants such as peroxides, , photocatalytic processes, , or hypervalent iodine reagents. − Continuous processes have been investigated as well . Despite these developments in organosulfur oxidation processes, most lack industrial interest, owing to sustainability, scaling-up, and safety concerns.…”

Recent Advances in the Electrochemical Synthesis of Organosulfur Compounds

“…Taking into account the value of organosulfur oxidation processes, many efforts have been made to develop more sustainable oxidative methods that have a major impact on the industry in reducing chemical waste, toxic by‐products and costs. Generally, the oxidation of organosulfur compounds can be achieved with peroxides, [7,8] hypervalent iodine reagents [9,10] or through photocatalytic processes [11] . Despite the various documented procedures, the oxidation processes for organosulfur compounds are often constrained by a difficult scale‐up, by low sustainability and the use of hazardous oxidising reagents.…”