Steric control of tautomerism in tetrapyrroles: Iso-oxophlorins
5-Oxophlorins possessing a 15-substituent (e.g. 5) tend to exist in the tautomeric iso-oxophlorin form 8 in order to minimize steric interactions between the 15-group and its abutting substituents; the structure of 8 is established by spectroscopic methods and by X-ray crystallography.
Publication Source (Journal or Book title)
Khoury, R., Jaquinod, L., Nurco, D., & Smith, K. (1996). Steric control of tautomerism in tetrapyrroles: Iso-oxophlorins. Chemical Communications (10), 1143-1144. https://doi.org/10.1039/cc9960001143