Synthesis of a Bisvinylogous Octaethylporphyrin

Abstract

Phorochem. Photohiol. 44 (1986) 5 5 5 ; E. Vogel, M. Kocher, M. Balci, I. Teichler. J. Lex. H. Schmickler, 0. Ermer, Angew. Chem. 99 (1987) 912; Angew. Chem. Int. Ed. Engl. 26 (1987) 931; B. Wehrle, H.-H. Limbach, M. Kocher. 0. Ermer, E. Vogel, ihid. 99 (1987) 914 and 26 (1987) 934; H. (Universitlt Heidelberg) for performing these calculations.[8] In the case of the porphycene parent compound, reaction with bromine also leads exclusively to P-pyrrolic bromination, but the bromine substituent is found in the 2-position, which is occupied by a propyl group in 5. 2-Bromoporphycene is the only isolated monobromination product (unpublished results with K . Pramod and H.-J. Dunnwuhf). This substitution pattern for bromination is different from that of porphyrin, for which regioselective substitution at the methine bridge leads to the formation of 5-bromoporphyrin [H.

Synthetic Expanded Porphyrin Chemistry

“…While this limited the study of superphthalocyanine itself, the very fact that it could be made helped inspire a number of other historically important developments, including the synthesis of pentaphyrin (for example, 4) by Rexhausen and Gossauer, [27] the preparation of so-called platyrins (for example, 5) by Berger and LeGoff, [28] and the generation of a whole series of "stretched" systems (for example, 6) by Franck and co-workers. [21,29] Another important boost to the generalized area of porphyrin analogues came with the synthesis of porphycene (7) by Vogel et al in 1986. [30] This first of now many porphyrin isomers represented a milestone in the chemistry of oligopyrrolic macrocycles and helped highlight the fact that porphyrin analogues need not be expanded to be interesting.…”

“…The results are similar to what was found for the analogous bisvinylogous porphyrin 6 (n = 0) reported by Franck and co-workers. [29] Further support for the aromatic nature of 16 was obtained from UV/Vis spectroscopic analyses. The spectrum of 16 was found to contain a strong, split transition with two absorption maxima at l max = 468 and 496 nm, which presumably corresponds to the intense, formally allowed, B, or Soret band seen in the spectra of porphyrins.…”

Tailor-made aromatic porphyrinoids with NIR absorption

“…Franck et al further reported [22] bisvinylogous octaethylporphyrin (1.3.1.3), 126 , via acid catalysed condensation of biladiene P125 with formaldehyde followed by oxidation using DDQ (Scheme 29). 65 The 1 H NMR spectrum of 126 in CDCl 3 /1% trifluoroacetic acid (TFA) revealed pronounced aromaticity with the signals for the inner and outer bridge protons being strongly upfield and downfield shifted, respectively, with Δ δ = 20.2 ppm.…”

Activation of Small Molecules (H2, CO2, N2O, CH4, and C6H6) by a Porphyrinoid-Based Dimagnesium(I) Complex, an Electride

“…20 In 1990, [22]octaethylporphyrin(3.1.3.1) has been synthesized where the inner ring of the porphyrin unit has been extended by four carbon atoms. 16,18 This extended porphyrin has 22 π-electrons (follows Hückel’s (4 n + 2) rule, n = 5) and hence is aromatic in nature. 17…”

“…Porphyrins are one of the important classes of macrocycles, where four pyrrole units are connected alternately through methine (CH−) linkers . The 18 conjugated π-electrons ((4 n + 2) π-electrons; n = 4) present in the porphyrins make it highly aromatic. − The deprotonated free base porphyrins can form complexes with metal atoms; they are known as metalloporphyrins, which are fundamental units of a number of biomolecules without which life on this earth cannot survive. , The core of the porphyrin has been extended and stretched using bridging atoms. − These modified porphyrinoid cores have strong red-shifted UV–vis absorption that has potential applications in photochemistry as photosensitizers. , The stretched porphyrinoid cores can be used as ligands for the generation of unusual metalloderivatives . In 1990, [22]­octaethylporphyrin(3.1.3.1) has been synthesized where the inner ring of the porphyrin unit has been extended by four carbon atoms. , This extended porphyrin has 22 π-electrons (follows Hückel’s (4 n + 2) rule, n = 5) and hence is aromatic in nature …”