Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Vinylogous porphyrins

The octaethyl analogue of 283 was recently synthesized by Franck and coworkers [195]. Condensation of 284 with the a-free dipyrromethane 285 gave the biladiene 286 which, when reacted with formaldehyde and subsequently oxidized with DDQ, gave the vinylogous porphyrin 287 (Scheme 53) [195]. This... [Pg.254]

Two new expanded porphyrins, that would perhaps best be classified as vinylogous porphyrins, have also been reported in the last several months. Corriu et al. have developed a facile synthesis of new tetrapyrrolic macrocyclic derivatives [241]. A notable difference between these new vinylogous porphyrins and those described above (Section 11) is the incorporation of pyridine, in one case, as part of the macrocycle. While these new expanded porphyrins are not aromatic, they may have great potential as ligands. Indeed, the formation of a bimetallic palladium complex was described. [Pg.272]

A variation of the general theme of pyrrole containing vinylogous porphyrins has been attempted by Street. In this new system imidasiles replace the pyrroles to give a new coronand class [242]. [Pg.272]

Figure 11) and vinylogous porphyrins [246,264], (e.g. 25 and 27 Figure 12), which appear attractive because they too appear to overcome many of the deficiencies seen with Photofrin. In particular, many of these agents are monomeric species that absorb in the far-red spectral region and which show favorable (i.e, low) toxicity characteristics in vivo. [Pg.268]

Much of the original interest in preparing vinylogous porphyrins stemmed from a desire to obtain annulene-like systems with large, extended jr-conjugation pathways that could be used both to explore the limits of aromaticity and test for the possible existence of antiaromaticity. As will be discussed later on in this chapter,... [Pg.204]

The largest vinylogous porphyrin prepared to date was first reported by Knubel and Franck in 1988. It is the 34 Ji-electron octavinylogous [34]porphyrin-... [Pg.215]

Vinylogous porphyrins are formally built up of odd-numbered carbon spacers separating four pyrrole rings. There are, however, several expanded porphyrins that contain four pyrrolic or pyrrole-like subunits that contain only even-numbered carbon spacers. These macrocycles will be grouped under the general heading stretched porphycenes , since they are typically prepared via the low-valent titanium mediated coupling of pyrrolic aldehydes just as are the porphycenes (cf. Chapter 3). [Pg.216]

Reference 87 gives an example of a promising expanded porphyrin lead whose current level of development (i.e., in vitro and/or in vivo analysis) does not yet warrant specific mention in this chapter, "interestingly, nearly coincident with Sessler and coworkers, Franck proposed that certain vinylogous porphyrins might also be useful as PDT sensitizers (see footnote 3 in reference 90). [Pg.436]

Sapphyrins and Vinylogous Porphyrins X-Ray Radiation Therapy Enhancement... [Pg.530]


See other pages where Vinylogous porphyrins is mentioned: [Pg.178]    [Pg.178]    [Pg.251]    [Pg.252]    [Pg.256]    [Pg.256]    [Pg.262]    [Pg.263]    [Pg.279]    [Pg.4]    [Pg.7]    [Pg.185]    [Pg.204]    [Pg.205]    [Pg.205]    [Pg.208]    [Pg.209]    [Pg.240]    [Pg.436]    [Pg.442]    [Pg.442]    [Pg.442]    [Pg.454]    [Pg.527]    [Pg.35]    [Pg.158]    [Pg.205]    [Pg.205]    [Pg.211]   
See also in sourсe #XX -- [ Pg.4 , Pg.185 , Pg.204 , Pg.205 , Pg.208 , Pg.215 , Pg.216 , Pg.240 , Pg.436 , Pg.442 , Pg.454 ]




SEARCH



Vinylogization

Vinylogous

Vinylogs vinylogous

Vinylogy

© 2024 chempedia.info