Furan-thiophene porphycene

Scheme 85 Synthesis of mixed furan-thiophene porphycene.

Structural variations of tetrapyrrolic porphycene 38 (Scheme 17) in such a way that an 18jt-electron conjugation pathway is retained, have furnished a variety of neutral as well as charged porphycene analogues. These variations mainly include replacement of a pyrrole heterocycle with furan, thiophene, or imidazole. 

We have compiled synthetic chemistry and properties of porphyrin analogues containing only furan, imidazole, or thiophene subunits in place of pyrrole subunit(s). Expanded porphyrinoids have been excluded. This write-up is not intended to give a comprehensive treatment, but is aimed to complement earlier reviews (06CCR468, 08CSR215). In the following two sections, the chemistry of core-modified porphycenes and porphyrins is presented. 

After the preparation of porphycene and its substituted derivatives such as 135 [174], a variety of porphyrin analogues were isolated, in which pyrrole units were replaced with furan or thiophene rings and/or extended by additional ring systems [135, 175-185] these are illustrated by compounds 136-142 (Figures 6.23 and... 

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