Porphyrins and derivatives: Synthetic strategies and reactivity profiles

Porphyrins, usually as metal complexes of either iron or magnesium, are wid ely distributed in nature, and exist as the prosthetic groups in a wide var iety of primary metabolites such as hemoglobins, myoglobins, cytochromes, c atalases, peroxidases, chlorophylls, and bacteriochlorophylls. This article describes the current best methodology for preparation of simple, symmetri cal model porphyrins, as well as more complex protocols for preparation of unsymmetrically substituted porphyrin systems similar to those found in nat ure. Basic chemical reactivity of porphyrin and metalloporphyrin systems ar e then described systematically, using a reactivity profile approach. The d iscussion of reactivity includes newer developments in this field, focussin g on electrophilic and nucleophilic reactions, oxidation, reduction, cycloa ddition reactions and intramolecular cyclizations. Using the reactivity pro files presented, porphyrin systems can be functionalized and transformed in to novel arrays and systems, and these are providing valuable contributions to catalytic, electron transport, biological and medicinal chemistry.