SYNTHESIS AND METALATION OF INTERNALLY ALKYLATED PORPHYRINOIDS
Alkylation of benzocarbaporphyrin 1 afforded asymmetrical N-alkyl derivatives 2, which underwent metalation with palladium(II) acetate to afford palladium(II) complexes where the internal alkyl group had migrated from the 22- to the 21-position. To investigate the mechanism behind the migration, 23-methylbenzocarbaporphyrin 3 was synthesized from a N-methyltripyrrane and an indene dialdehyde. Carbaporphyrin 3 was metalated with palladium(II) acetate and it was found that alkyl group migration still occurred, albeit at a slower rate, to give a mixture of 23-methyl and 21-methyl palladium(II) complexes. Methylcarbaporphyrin 3 also underwent a rearrangement upon metalation with [Rh(CO)2Cl]2 to give a methylene bridged derivative 4. By utilizing MacDonald-type '3+1' condensations, the N-methyl tripyrrane was reacted with 5-formylsalicylaldehyde, 3-hydroxy-2,6-pyridinedicarbaldehyde, 2,5-thiophene and furan dialdehydes, and 5-methyl-2,4-pyrroledicarbaldehyde to afford a series of N-methylated porphyrins 5-8. Metalation of these internally alkylated porphyrinoids is currently under investigation.
Latham, Alissa, "SYNTHESIS AND METALATION OF INTERNALLY ALKYLATED PORPHYRINOIDS" (2019). University Research Symposium. 200.