What is the difference between threo/erythro ephedrine? [closed]








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I want to know how to easily make the difference or just understand the importance of stereocenters of ephedrine ?




**1.Ephedrine exhibits optical isomerism and has two chiral centres, giving rise to four stereo isomers. By convention, the pair of enantiomers with the stereochemistry (1R,2S and 1S,2R) is designated ephedrine, while the pair of enantiomers with the stereochemistry (1R,2R and 1S,2S) is called pseudoephedrine.**
Source :<https://en.m.wikipedia.org/wiki/Ephedrine>


2. Again in order to distinguish threo from erythro.. Just memorize the word :TOES =Threo - Opposite Erythro - Same
e. g., ![Threo - Erythro ](https://i.stack.imgur.com/IqtLT.jpg)


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