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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
Author(s) -
Silva Ana M. G.,
de Oliveira Kleber T.,
Faustino Maria A. F.,
Neves Maria G. P. M. S.,
Tomé Augusto C.,
Silva Artur M. S.,
Cavaleiro José A. S.,
Brandão Paula,
Felix Vítor
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200700852
Subject(s) - chemistry , adduct , ylide , planarity testing , allylic rearrangement , wittig reaction , yield (engineering) , cycloaddition , medicinal chemistry , stereochemistry , organic chemistry , crystallography , catalysis , materials science , metallurgy
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)