Chiral atropisomeric metalloporphyrins in the enantioselective styrene epoxidation

A new series of porphyrins has been synthesised, incorporating four identic al chiral binaphthyl derivatives in the meso-positions. Owing to a hindered rotation around the bond between the naphthyl and the porphyrin, four atro pisomers are generated, which were fully separated by preparative TLC and t horoughly characterised. The free bases were metallated with iron(III) and manganese(III) and the resulting complexes were used as catalytic precursor s in styrene epoxidation. The reactions show chemoselectivity and enantiose lectivity, depending on the stereochemistry of the metalloporphyrin. It is demonstrated that highest efficiency is performed by the alpha alpha beta b eta isomer, showing C-2 symmetry.