Metal-organic assembly with quasi-salen Mn(III) active units was prepared by in situ self-assembly of linked 4,4'-methylenebis(6-(sec-butylimino)methyl) phenol ligand with manganese ion and gave comparable catalytic activity in the epoxidation of conjugated non-functionalized alkenes relative to the traditional salen Mn(III) complex. More importantly, the quasi-salen Mn(III) assembly could be conveniently recycled.