Protonation, alkylation, and acetylation of corroles and 21,24-dioxacorroles

Abstract

Formation of corrole dications is shown to involve protonation at C-5 rather than at C-10. A series of N(21)- and N(22)-alkylcorroles (alkyl = methyl, ethyl, allyl, or 3,3-dimethylallyl) has been prepared and although the N(21)-isomers and the N(22)-methyl and -ethyl derivatives are thermally stable, the N(22)-allyl and -(3,3-dimethylallyl) derivatives were transformed into mixtures of the N(21)-isomers and the unsubstituted corrole when they were heated in refluxing toluene. Further methylation of the N(21)- or N(22)-methylcorrole with methyl iodide yielded an NN′-dimethylcorrole iodide which gave the N(21)-methylcorrole when heated at 180°. Acetylation of corroles yielded the N(21)-acetyl derivatives. Alkylation of 21,24-dioxacorrole gave mixtures of mono- and di-N-alkylated products, the 22,23-dimethyl derivative having trans-22- and 23-methyl substituents, as shown by the resolution of the D-camphorsulphonate. Acetylation of 21,24-dioxacorrole gave a mixture of the 5-monoacetyl and 2,18-(3,17?-) diacetyl derivatives.