A new method for the synthesis of porphyrin-α-diones that is applicable to the synthesis of trans-annular extended porphyrin systems

Abstract

Porphyrin-α-diones can be prepared by photooxidation or SeO₂-oxidation of β-hydroxyporphyrins, which are in turn readily synthesized from the corresponding copper(II) or nickel(II) 2-halo- and 2-sulphinyl-porphyrins by reaction with the anion of E-benzaldoxime; the efficient conversion of the porphyrinoquinoxaline 6 into the diquinoxalino[2,3-g, 2,3-q] porphyrin 9 illustrates the usefulness of the new methodology for the synthesis of trans-annular extended porphyrin systems.