Question: what kind of isomers are ephedrine and pseudoephedrine?
Answer: 1. Introduction. Ephedrine has two chiral centres and can therefore exist in the form of four stereoisomers: 1R,2S-(-)-ephedrine, 1S,2R-(+)-ephedrine, 1S,2S-(+)-pseudoephedrine and 1R,2R-(-)-pseudoephedrine (Table 1).