The shrub ma huang (Section 5.4A) contains two biologically active stereoisomers-ephedrine...

The shrub ma huang (Section 5.4A) contains two biologically active stereoisomers-ephedrine and pseudoephedrine-with two stereogenic centers as shown in the given structure. Ephedrine is one component of a once popular combination drug used by body builders to increase energy and alertness, while pseudoephedrine is a nasal decongestant.

a.  Draw the structure of naturally occurring (−)-ephedrine, which has the 1R,2S configuration.

b.  Draw the structure of naturally occurring (+)-pseudoephedrine, which has the 1S,2S configuration.

c.  How are ephedrine and pseudoephedrine related?

d.  Draw all other stereoisomers of ephedrine and pseudoephedrine and give the R,S designation for all stereogenic centers.

e.  How is each compound drawn in part (d) related to ephedrine