To understand synthesis check this website and this guy on youtube
http://www.organic-chemistry.org/
I used this heavy when I was in school. Drug synthesis is pretty complex when you get down to (R,S) conformations and cis and trans; because you may synthesize a drug in the R' conformation; but when it's inside of the human body it can change into the S' conformation and can cause harm just like thalidomide. The R' thalidomide was given to women and then when it reached the liver and it metabolized into S' thalidomide by hydrolysis and caused serious birth defects. But the main thing is understand the reactions
http://www.organic-chemistry.org/namedreactions/ ,
http://www.masterorganicchemistry.com/reaction-guide/ ,
http://sites.tufts.edu/andrewrosen/files/2012/11/Orgo-I-Overview1.pdf
DS is pretty fun but there is a difference between paper chemistry and bench chemistry; you think it will work on paper but you can get a different out come when you get on the bench.
I was planning on going into the pharmaceutical industry and try to get my MS in pharmaceutical science; but life happened.
Right now I work in R&D but in the petro/polymer chemistry field. R&D is cool but you have to deal with a lot of egos and shyt. For you trying to get into the drug field; make sure you take p chem and o chem seriously and in O chem understand FT-IR, GC-MS and NMR. In the R&D lab when you first start out your going to get all the shyt the lead chemist don't want to do. They will tell you synthesize this ______ and I need it by the end if the day or I need it by xyz day. R&D is real laid back and when you know your shyt you can talk a lot of shyt.
The p chem will help you out because there are some medicines in which you would have to do physical labor like emulsions:
They will give you projects to do; but they will train you (sometimes); a lot of the stuff I learned I had to do it on my own with no help. I did fukk up; but you learn from your mistakes. Also I did not start in R&D I had to work my way up aka the hard way.
Before I got into this field I worked as a molecular biologist testing pharmaceutical drugs for hiv research and other bloodborne pathogens.