cis–trans Isomerisation and atropisomerism of octaethyl 1,2-bis(coproporphyrinyl)ethylene ester

Abstract
Oxidation of the ethane-bridged dimer of coproporphyrin-I proceeds stereoselectively to produce only the sterically unhindered trans-ethylene-bridged atropisomer, which undergoes thermal isomerisation to give two atropisomers of the cis-dimer.