DEAD is a reagent in the Mitsunobu reaction where it forms an adduct with phosphines (usually triphenylphosphine) and assists the synthesis of esters, ethers, amines and thioethers from alcohols. Reactions normally result in the inversion of molecular symmetry.
DEAD was used in the original 1967 article by Oyo Mitsunobu, and his 1981 review on the use of diethyl azodicarboxylate is a top-cited chemistry article. The Mitsunobu reaction has several applications in the synthesis of natural products and pharmaceuticals.
In the above reaction, which is assisted either by DEAD or DIAD (diisopropyl azodicarboxylate), thymidine 1 transforms to the derivative 2. The latter easily converts to zidovudine 4 (also known as azidothymidine or AZT), an important antiviral drug, used among others in the treatment of AIDS. Another example of pharmaceutical application of DEAD-assisted Mitsunobu reaction is the synthesis of bis[(pivaloyloxy)methyl [PIVz] derivative of 2-deoxy-5-fluorouridine 5-monophosphate (FdUMP), which is a potent antitumor agent.