Stirring the porphyrin alphabet soup—functionalization reactions for porphyrins

Abstract

[DO NOT ALTER/DELETE THIS TEXT]Advances in the synthesis of unsymmetrically meso substituted porphyrins are based on the development of new total syntheses and porphyrin functionalization methods. These methods have replaced earlier mixed condensation reactions and give synthetic access to almost any desired meso-substituted porphyrin. They include the complete series of porphyrin homologues and regioisomers of the A x -series with either alkyl or 10 aryl residues, and numerous examples of ABCD-type chromophores. The syntheses are based on a combination of classic functionalization reactions, the use of organolithium reagents in S N Ar reactions, and organometallic reactions with Pd, Ni, Cr, Ru, B, and Sn catalysis. This feature article gives an account of our work in the past decade to develop synthetic methods for the A x -and ABCD-type porphyrins and their use as optical materials and photosensitizers.

Porphyrin substituent regiochemistry, conformation and packing – the case of 5,10-diphenylporphyrin

“…Clearly, the different arrangement of the meso substituents has an impact on the conformation of the free base porphyrins and on the packing arrangement. This provides further information on the structural variability of the various members of the A x -and ABCD-porphyrin family [17]. It also indicates the possibility that the 5,10-disubstituted porphyrins, with appropriate functional groups, might give rise to unique packing arrangements in the context of crystal engineering [18].…”

mTHPC – A drug on its way from second to third generation photosensitizer?

“…More significant synthetic advances of Temoporfin related compounds are a consequence of general progress in the synthesis of unsymmetrical porphyrins and (bacterio)chlorins [42,43,44,45,46,47,48,49]. These advances have made it possible to prepare porphyrins with different substituent pattern, e.g., different hydrophobic and hydrophilic groups.…”

“…4). This includes unsymmetrical systems of the ABCD-type porphyrins and the A x -type porphyrins with one to four meso residues [46,50,51]. For example, the use of both condensation and substitution reactions allowed the rapid generation of a large library of amphiphilic derivatives of mTHPC with both aryl and alkyl residues [52].…”

Chemical Synthesis and Medicinal Applications of Glycoporphyrins

“…Partial and total syntheses were facilitated first by the MacDonald condensation, a [2+2] condensation utilizing dipyrromethenes, dipyrroyl ketones and dipyrromethanes [138] . Condensation methods are continuously improving and almost any desired meso or β-substituted porphyrin can be prepared today [139][140][141][142] . In parallel the functionalization of porphyrins through functional group interconversions and direct substitution reactions has progressed dramatically in the past decades [140,143] .…”

“…Condensation methods are continuously improving and almost any desired meso or β-substituted porphyrin can be prepared today [139][140][141][142] . In parallel the functionalization of porphyrins through functional group interconversions and direct substitution reactions has progressed dramatically in the past decades [140,143] . This is mainly a result of the use of organolithium [144,145] and transition metal catalyzed reactions [143,146] which now allows the preparation of unsymmetrical ABCD-type meso substituted porphyrins and arrays [139,147,148] .…”