Biosynthetic and biomimetic electrocyclizations

A review on the biosynthetic and biomimetic electrocyclizations is presented that aims to provide a counterpart highlighting electrocyclic reactions that have been found or suspected in the biosynthesis of natural products. This review is organized beginning from the number of electrons involved in a given π system that undergoes the electrocyclic reaction, followed by electrocyclic reactions involving 6 and 8 π-electrons. Thermal and photochemical reactions are presented in the same order, while, systems that include heteroatoms which are confined to 6 π-electrons are presented separately. Finally, briefly addressed is the question of whether biosynthetic electrocyclizations require enzyme catalysis.