Editing Epimer (section)

==Epimerization==
Epimerization is a chemical process where an epimer is converted to its diastereomeric counterpart.<ref name="Clayden"/> It can happen in [[condensed tannins depolymerization]] reactions. Epimerization can be spontaneous (generally a slow process), or catalysed by enzymes, e.g. the epimerization between the sugars [[N-acetylglucosamine|''N''-acetylglucosamine]] and [[N-acetylmannosamine|''N''-acetylmannosamine]], which is catalysed by [[RENBP|renin-binding protein]].

The penultimate step in Zhang & Trudell's classic [[epibatidine]] synthesis is an example of epimerization.<ref name="ZhangTrudell1996">{{cite journal|last1=Zhang|first1=Chunming|last2=Trudell|first2=Mark L.|title=A Short and Efficient Total Synthesis of (±)-Epibatidine|journal=The Journal of Organic Chemistry|volume=61|issue=20|year=1996|pages=7189–7191|issn=0022-3263|doi=10.1021/jo9608681|pmid=11667626}}</ref> Pharmaceutical examples include epimerization of the [[Diastereomer#Erythro_/_threo|erythro isomers]] of [[methylphenidate]] to the pharmacologically preferred and lower-energy threo isomers, and undesired ''in vivo'' epimerization of [[tesofensine]] to [[brasofensine]].