Porphyrins isomeric

Another alternative makes use of the condensation of 5,5 -dimethyidipyrryimethenes8and 5,5 -dibromodipyrrylmethenes 9 in organic melts. In this case, the method allows the synthesis of more diversely substituted porphyrins 10. To avoid constitutionally isomeric porphyrins it is neccessary to start with one dipyrrylmcthene which is symmetrically substituted about the methine carbon. 

Sessler, J.L. Weghorn, S. J. Expanded, Contracted and Isomeric Porphyrins, Pergamon Oxford, 1997. 

The tetramerization of suitable monopyrroles is one of the simplest and most effective approaches to prepare porphyrins (see Section 1.1.1.1.). This approach, which is best carried out with a-(hydroxymethyl)- or ot-(aminomethyl)pyrroles, can be designated as a biomimetic synthesis because nature also uses the x-(aminomethyl)pyrrole porphobilinogen to produce uroporphyrinogen III. the key intermediate in the biosynthesis of all kinds of naturally occurring porphyrins, hydroporphyrins and corrins. The only restriction of this tetramerization method is the fact that tnonopyrroles with different -substituents form a mixture of four constitutionally isomeric porphyrins named as porphyrins I, II, III, and IV. In the porphyrin biosynthesis starting from porphobilinogen, which has an acetic acid and a propionic acid side chain in the y6-positions, this tetramerization is enzymatically controlled so that only the type III constitutional isomer is formed. 

SESSLER WEGHORN Expanded Contracted Isomeric Porphyrins... 

PELLETIER Alkaloids Chemical and Biological Perspectives SESSLER WEGHORN Expanded Contracted and Isomeric Porphyrins WONG WHITESIDES Enzymes in Synthetic Organic Chemistry... 

Porphyrin quinones serve as biomimetic models for fundamental studies on photo-induced ET. Most studies have been performed with the well-known porphyrin p-quinones and the isomeric porphyrin o-quinones have been mostly neglected due to their higher chemical reactivity but in fact they should be better electron acceptors. Speck et al. synthesized several porphyrin o-quinones and have shown that a facile and simple variation of AGEt can be achieved by using in situ formed semiquinones for metal chelation230. 

Sessler JL, Weghorn SJ (1997) Expanded, contracted, and isomeric porphyrins. Elsevier, New York... 

MATHEY Phosphorus-Carbon Heterocyclic Chemistry The Rise of a New Domain McKILLOP Advanced Problems in Organic Reaction Mechanisms OBRECHT Solid Supported Combinatorial and Parallel Synthesis of Small-Molecular-Weight Compound Libraries OSBORN Best Synthetic Methods - Carbohydrates PELLETIER Alkaloids Chemical and Biological Perspectives SESSLER WEGHORN Expanded Contracted and Isomeric Porphyrins WONG WHITESIDES Enzymes in Synthetic Organic Chemistry... 

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