Synthesis, characterisation and catalytic use of iron porphyrin amino ester conjugates

Abstract

The present study deals with the synthesis and characterisation of C₂-symmetrical chiral Fe(III)(porphyrin)(OMe) catalysts; these catalysts display a totem structure, where each section is assigned to have a specific catalytic activity. The chiral portions of the porphyrin ligand are constituted by amino acid residues, which form a chiral cavity by surrounding both faces of the porphyrin plane, as clearly displayed by the X-ray structure of a free-base porphyrin. The Fe(III)(porphyrin)(OMe)-catalysed cyclopropanation of α-methylstyrene by diazo compounds occurred with excellent diastereoselectivities and a modest enantiocontrol. Thus, the obtained catalytic results have been rationalised by performing a DFT investigation and will be fundamental in the future modification of the molecular structure of chiral ligands to improve their catalytic performance.