Molybdenum(VI)-complexes with chiral N,O-ligands derived from carbohydrates: Synthesis, structure and catalytic properties in asymmetric olefin epoxidation

Novel chiral 2′-pyridinyl alcohols derived from isopropylidene-protected carbohydrates are reported. They show different characteristics at the hydroxy group, but are all suitable ligands for chiral molybdenum(VI) complexes of the type MoO₂ (L = chiral 2′-pyridinyl alcoholate). MoO₂ (acac)₂ served as starting material in the complex syntheses. The structure of one ligand and one dioxo complex were exemplary established by X-ray crystallography. For catalytic runs in the enantioselective epoxidation catalysis trans -methylstyrene was used as model substrate, tert -butylhydroperoxide and cumolhydroperoxide, resp., as the oxidant.