Nomenclature
The dextrorotary (+)- or d- enantiomer is (1S,2R)-Ephedrine, whereas the levorotatory (−)- or l- form is (1R,2S)-Ephedrine.
In the outdated d/l system (+)-Ephedrine is also referred to as l-Ephedrine and (—)-Ephedrine as d-Ephedrine (in the Fisher projection then the phenylring is drawn at bottom).
Often the d/l system (with small caps) and the d/l system (with lower-case) are confused. The result is that the levorotary l-Ephedrine is wrongly named l-Ephedrine and the dextrorotary d-Pseudoephedrine (the diastereomer) wrongly d-Pseudoephedrine.
The IUPAC names of the two enantiomers are (1R,2S)- respectively (1S,2R)-2-methylamino-1-phenylpropan-1-ol. A synonym is erythro-Ephedrine.
Read more about this topic: Ephedrine