Glucopyranosylamine-Derived Dinuclear Mo(VI) Complex: An Efficient Catalyst for the Oxidation of Thiols into Uronium Aryl/Alkyl Sulfonates.

A combination of dinuclear molybdenum complex of bis-(4,6-O-ethylidene-β-D-glucopyranosylamine)-1,4-dihydroxy-2,5-dibenzylidene with urea hydrogen peroxide (UHP) has been used as an efficient catalyst for the selective oxidation of thiols into corresponding uronium sulfonate salts (UrR/ArSO₃). The reaction was carried out in ethanol at room temperature using sixteen different aliphatic and aromatic thiols, which afforded an excellent isolated yield of products (89-98 %). We have established the evolution of hydrogen gas during the oxidation process by gas chromatography, however no such reports are available for similar reactions in the past. The products have been characterized by several analytical techniques like FTIR, NMR, HRMS, etc., and the molecular structure of two compounds has been established by single crystal X-ray diffraction studies. The mechanistic insights of the catalytic process have also been explored, and during this process, the formation of disulfides, sulfinothioates, and sulfinic acids has been noticed. Two representative reactions have also been reported where (i) uronium p-chlorobenzene sulfonate has been converted to corresponding sulfonic acid and (ii) diphenyl diselenide has been oxidized to corresponding selenonate salt.