Porphyrins and related compounds

Porphyrins are the most widespread macrocyclic compounds in nature. Synthetic porphyrins, which can be obtained in good yields from quite cheap raw materials by simple technology, are also of interest. Substances containing the porphin nucleus as a cyclic backbone are usually referred to as porphyrins (Eq. 2.216) [231]. 

By tetramerisation of pyrroles having a methylene unit in one of the a positions, e.g. H2L557, it is possible to prepare coproporphyrin tetramethylene ester H2L558 in 29% yield [403], In the presence of cobalt(II) chloride, H2L558 is assembled in the form of the corresponding complex, in considerably greater yield (52%) (Eq. 2.218) [403]. 

By reaction of the dihydroxymethyl derivative HL563 with copper(II) acetate, [Cu(L564)] is formed in 21% yield (Eq. 2.220) [405]. 

By intramolecular coupling tetrapyrrole systems H2L565 and H2L566, complexes [Cu(L567)] and [Cu(L568)] were synthesised in the presence of copper(II) (Eq. 2.221) [406]. 

The methodology for constructing porphyrins employing copper(II) salts as templates for cyclisation of tetrap)OTole ligsons [405] has been generalised [407-411] 

---

L. R. Milgrom, in The Colors of Life An Introduction to the Chemistry of Porphyrins and Related Compounds , Oxford Univ. Press, 1997. 

F. Aromatic and Heteroaromatic Large Rings 1. Porphyrins and Related Compounds... 

---