We know the recent hue and cry about the stock piling of Tamiflu (Oseltamivir) and there by the deficiency of the drug. The commercially (see the below scheme; source : wikipedia) used method i.e., Karpf / Trussardi synthesis make use of Shikimic acid. Many researchers have tried alternative raw materials for the synthesis of the drug and are successful also (see other schemes).
Now Anqi Chen and Christina Chai of Shionogi & Co., Ltd have come up with a new process for making the drug that does not use shikimic acid. They found that D-ribose, a naturally-occurring sugar produced by fermentation in large scales, potentially provides an inexpensive and abundant source of starting material for making the drug. D-ribose costs only about one-sixth as much as shikimic acid. In lab studies, the scientists demonstrated the potential use of D-ribose as an alternative source for the synthesis of Tamiflu.
As per the claim by the authors, the concise alternative route (12 steps) does not utilize protecting groups and features the introduction of 3-pentylidene ketal as the latent 3-pentyl ether, the use of a highly efficient RCM reaction to form the Tamiflu skeleton, and selective functional group manipulations (see Scheme 2, source : Organic Letters)
Ref : http://pubs.acs.org/doi/abs/10.1021/ol9024716