3a. Lamivudine is a drug used for the treatment of HIV (AIDS). This drug stop HIV from infecting cells in the body. Only the (-)-enantiomer of lamivudine is registered for

the treatment of HIV because it is more active and less toxic than either the (+)-enantiomer or the race mate. In the (-)-enantiomer, the chiralcentre at position 2 has the R configuration and the chiral centre at position 5has the S configuration. Draw the structure of (-)-lamivudine using hashed and wedged line notions that represents R configuration at 2 and S configuration at