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Chemical Transformations of Mono‐ and Bis(buta‐1,3‐dien‐1‐yl)porphyrins: A New Synthetic Approach to Mono‐ and Dibenzoporphyrins

2007; Wiley; Volume: 2008; Issue: 4 Linguagem: Inglês

10.1002/ejoc.200700852

1434-193X

Ana M. G. Silva, Kléber T. de Oliveira, M. Amparo F. Faustino, Maria G. P. M. S. Neves, Augusto C. Tomé, Artur M. S. Silva, José A. S. Cavaleiro, Paula Brandão, Vı́tor Félix,

Photodynamic Therapy Research Studies

Abstract β‐Butadienyl‐ and β,β′‐dibutadienylporphyrins were prepared by the Wittig reaction of β‐formyl‐ and β,β′‐diformyl‐ meso ‐tetraphenylporphyrins with allylic phosphorus ylide. Subsequent treatment of β‐butadienylporphyrin with dienophiles afforded the corresponding Diels–Alder adducts. In the absence of dienophiles, β‐butadienylporphyrin underwent electrocyclization, followed by oxidation, to give monobenzoporphyrin in good yield. Similarly, adjacent and opposite dibenzoporphyrins were successfully synthesized from adjacent and opposite β,β′‐dibutadienylporphyrins, respectively. This is the first report of electrocyclization of β‐butadienylporphyrins. The structures of mono‐ and dibenzoporphyrin nickel complexes, as well as of a Diels–Alder adduct, were determined by single‐crystal X‐ray diffraction; a strong distortion from the planarity of the porphyrin core was observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)