Simple methodology for syntheses of porphyrins possessing multiple peripheral substituents with an element of symmetry
New methodology was developed for synthesis of regiochemically pure porphyrins with D2h symmetry (e.g. 9) via tetramerization reactions involving two different pyrroles. The two pyrrole components were a 2,5-diunsubstituted pyrrole (e.g. 11) and a 2,5-bis[(N,N-dimethylamino)methyl]pyrrole (e.g. 10), the latter being formed from a 2,5-di-unsubstituted pyrrole by treatment with excess Eschenmoser's reagent (N,N-dimethylmethyleneammonium iodide). A bis-butanoporphyrin 16 was transformed into the corresponding opp-bis-benzoporphyrin 17 by treatment with DDQ. The synthetic method was further extended to allow the synthesis of more unsymmetrical porphyrins, with C2v, symmetry (e.g. 32), by reacting a tripyrrane (e.g. 27) with a 2,5-bis[(N,N-dimethylamino)-methyl]pyrrole (e.g. 18). The structures and substituent arrays in both type of porphyrins were confirmed by single-crystal X-ray crystallography.
Publication Source (Journal or Book title)
Journal of Organic Chemistry
Nguyen, L., Senge, M., & Smith, K. (1996). Simple methodology for syntheses of porphyrins possessing multiple peripheral substituents with an element of symmetry. Journal of Organic Chemistry, 61 (3), 998-1003. https://doi.org/10.1021/jo951870f