Chiral Salen Mn(III) Complex Axial Coordination Immobilized on Diamine Modified Alspp and Highly Efficient Large-Scale Epoxidation of Olefins as a Recoverable Catalyst

Abstract

Aluminium oligo-styrenyl phosphonate-hydrogen phosphate (AlSPP) was used as organic-inorganic hybrid support after chloromethylation, and then with using different diamines as a reactive surface modifier. We realized the homogeneous chiral salen Mn(III) complex axially immobilized on modified AlSPP by a covalent grafting method. The prepared heterogeneous salen Mn(III) complexes were characterized by different techniques such as FT-IR, diffusion reflection UV-Vis, AAS, XPS, N 2 volumetric adsorption, SEM, TEM and TG. The chiral salen Mn(III) complexes were immobilized onto the AlSPP through axial coordination for the first time with m-CPBA/NMO as an oxidant system for asymmetric epoxidation of unfunctionalized olefins. The supported catalyst showed very good performance in the asymmetric epoxidation of a-methylstyrene and indene. The catalyst could be easily recovered and reused without significant loss of activity and enantioselectivity after nine cycles. This novel heterogeneous catalyst could be efficiently used in large-scale reactions with the enantioselectivity being maintained at the same level, which offer great possibilities for application in industry.

Synthesis, Characterisation and Cytotoxic Activity Evaluation of New Metalsalen Complexes Based on the 1,2-bicyclo[2.2.2]octane Bridge

“…This is in agreement with the presence of a Mn(III) species stabilized as a salen complex as reported previously in the literature. 32 Scheme 2 : Mechanosynthesis of Mn(III) salen complex 7…”

Principal component analysis of Mn(salen) catalysts

“…39 The Jacobsen's catalyst serves as an example of the high levels of catalytic efficiency and stereoselectivity achieved by this class of transition metal complexes. This has triggered further developments in asymmetric catalysis, including the development of novel chiral Mn(salen) complexes, 39 the immobilisation of such complexes onto different supporting materials 21,22,28,37 and the rationalisation of the catalytic cycle of this family of compounds using both theoretical and experimental methods. 14,32,35,43 In the presence of a terminal oxidant, Mn(salen) complexes are typically oxidised to their oxo-Mn(salen) analogues.…”