It's amazing how challenging middle-sized organic molecules can still be. Moenomycin A is a natural antibiotic made of just 5 sugar rings, with a few modifications here and there. However, its total synthesis has only been accomplished this year, after 30 years of research around it.

Read my story here:

http://www.rsc.org/chemistryworld/News/2006/November/28110602.asp