Asymmetric Syntheses of Stavudine (d4T) and Cordycepin by Cycloisomerization of Alkynyl Alcohols to Endocyclic Enol Ethers

Abstract

Anti-AIDS deoxynucleosides like stavudine (d4T, 3) are now accessible in a short (five steps!) asymmetric synthesis. The “missing link” between the acyclic precursors and the product is a Mo(CO)5-catalyzed cycloisomerization. It yields the ether 2, the saccharide building block for many nucleosides, from 1 in 80% yield. R = tBuCO.