Synthesis, catalytic activity and recycle of novel dimeric salen-Mn(III) complexes in asymmetric epoxidation

Abstract Novel chiral dimeric salen-Mn complexes were synthesized and their catalytic effects in asymmetric epoxidation of non-functionalized alkenes were investigated. The study was undertaken using a dimeric catalyst to establish whether high enantioselectivity could be achieved just like its active monomer, and whether the bigger complex could be efficiently recovered and reused by a simple controlling solvent system. The result showed that high activity and enantioselectivity were achieved. The dimeric complex formation enhanced the catalyst’s reactivity and stability without compromising its enantioselectivity. Catalyst 3a , unlike its monomer, could be easily recovered and reused for several cycles under the mild reaction conditions before a marked decline in yield and ee was observed.