Novel homogeneous Salen Mn(III) catalysts synthesized from dialdehyde or diketone with o -aminophenol for catalyzing epoxidation of alkenes

eries of novel non-salicylaldehyde based Salen ligands have been synthesized from the condensation of dialdehyde or diketone with o -aminophenol and the corresponding manganese(III) complexes prepared by further coordination of them with Mn(OAc)_2· 2H_2O . FT-IR, UV–Vis spectra, chemical analysis and the structure optimized by Hartree-Fork/3-21G+ all indicated that the qualities of these novel Mn complexes were relative to their molecular structures. More specifically, glyoxal based Mn complex 2c, which was similar to the traditional Mn(III)-salicylethylenediamine, had a short carbon chain and non geometrical constraint of the aliphatic bridge in the two o -aminophenol, and its quality was the best when compared to glutaraldehyde, 2,4-pentanedione and 1,3-cyclohexanedione based Salen Mn(III) complexes (3c, 4c and 5c). And it was also the excellent catalyst for the epoxidations of several non-functionalized alkenes with molecular oxygen/sacrificial-isobutyaldehyde, PhI(OAc) 2 or H 2 O 2 as oxidant.