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Carbaporphyrinoids containing a pyridine moiety: 3-aza-meta-benziporphyrin and 24-thia-3-aza-meta-benziporphyrin.
Autorzy
Rok wydania
2005
Czasopismo
European Journal of Organic Chemistry
Strony
5039-5048
DOI
10.1002/ejoc.200500496
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
6,11,16,21-Tetraaryl-3-aza-m-benziporphyrin, an analog of 5,10,15,20-tetraarylporphyrin with one of the pyrrole units replaced by a pyridine ring pointing outwards, linked at β,β′ positions, was formed by condensation of 3,5-bis[phenyl(2-pyrrolyl)methyl]pyridine, pyrrole and p-tolualdehyde catalyzed by TFA. The [3+1] approach, which involved a condensation of 3,5-bis[phenyl(2-pyrrolyl)methyl]pyridine with 2,5-bis[hydroxy(p-tolyl)methyl]thiophene was applied to afford 6,11,16,21-tetraaryl-24-thia-3-aza-m-benziporphyrin. Introduction of bulky substituents at ortho positions of meso-aryl compounds, adjacent to the pyridine ring, resulted in an increase in the yield of condensation. 3-Aza-m-benziporphyrins and 24-thia-3-aza-m-benziporphyrins have the 1H NMR spectroscopic features of non-aromatic molecules. Crystal structures of 6,21-diphenyl-11,16-di-p-tolyl-3-aza-m-benziporphyrin and 6,21-diphenyl-11,16-di-p-tolyl-24-thia-3-aza-m-benziporphyrin were determined by X-ray crystallography. Both molecules show a similar degree of nonplanarity with the pyridine ring sharply tipped out of the N(23)X(24)N(25) plane, making room for the 6,21-phenyl groups which are almost coplanar with the macrocycle. The protonation of 6,21-diphenyl-11,16-di-p-tolyl-3-aza-m-benziporphyrin with trifluoroacetic acid proceeds stepwise, subsequently yielding two dicationic and one tricationic species. Protonated 6,21-diphenyl-11,16-di-p-tolyl-24-thia-3-aza-m-benziporphyrinreacts reversibly with water to give 6-hydroxy-6,21-diphenyl-11,16-di-p-tolyl-24-thia-3-aza-m-benziphlorin. The protonation of 6,21-dimesityl-11,16-di-p-tolyl-24-thia-3-aza-m-benziporphyrin initiates an unprecedented process, which converts the non-aromatic carbaporphyrinoid reversibly into the aromatic 2-hydroxy-6,21-dimesityl-11,16-di-p-tolyl-24-thia-3-aza-m-benzichlorin.
Adres publiczny
https://doi.org/10.1002/ejoc.200500496