Chiral macrocyclic salen Mn(III) complexes catalyzed enantioselective epoxidation of non-functionalized alkenes using NaOCl and urea H2O2 as oxidants

Organic carbonates as solvents in macrocyclic Mn(III) salen catalyzed asymmetric epoxidation of non-functionalized olefins

“…It determine the interactions between reaction partners; consequently have direct bearing on mode and stability of the transition states and intermediates, which is reflected in reaction outcome, i.e. conversion and selectivity [23]. Due to this reason exploring newer solvent systems for new and even well-known reactions has become an important area of research.…”

“…For the sake of comparison, the present epoxidation protocol was also studied with conventionally used oxidant NaOCl (Table 4). Complexes 1 and 2 were earlier reported [23] whereas; structurally similar complexes 3 and 4 are new and were synthesized according to the Scheme 1. The synthesis of complexes 3 and 4 is simpler as their respective ligands 3 and 4 were obtained directly in high purity without the use of column chromatography as compared to the synthesis of ligands 1 and 2 that required short silica gel column chromatography for their purification.…”

“…HPLC and GC traces of product epoxides were compared with their respective racemic samples. The complexes 1, 2 and 3, 4 were prepared via intermediate dialdehydes 6 [23] and 7 respectively according to Scheme 1.…”

“…Organic carbonates are polar aprotic solvents, which are noncorrosive, nontoxic and biodegradable, hence are safer, and environment friendly alternatives to conventionally used CH 2 Cl 2 (DCM), tetrahydrofuran (THF) and other hazardous aromatic solvents [21,22]. For the present study we have employed our earlier reported macrocyclic Mn(III) salen complexes 1, 2 [23] and two new but closely related complexes 3 and 4 for the epoxidation of several prochiral olefins in organic carbonates as reaction media using pyridine N-oxide (PyNO) as an axial ligand. This protocol worked equally well with sodium hypochlorite (NaOCl) and urea hydrogen peroxide (UHP) as oxidants in our initial exploratory experiment.…”

A novel Schiff base of Mn(III) complex supported on magnetic cobalt nanoparticles as a highly efficient retrievable heterogeneous catalyst in oxidation of alcohols and sulfides compounds

“…In recent years, immobilization of Mn(III) complexes on solid supports has attracted considerable attention due to the some of the advantages such as easy separation from the reaction mixture and simple recycling of heterogeneous catalysts in the reaction system [34][35][36][37].…”