Diastereoselective Synthesis of 2′-Dihalopyrimidine Ribonucleoside Inhibitors of Hepatitis C Virus Replication

Abstract

We present a newly developed synthetic route to 2-bromo-2-fluoro ribolactone based on our published 2-chloro-2-fluoro ribolactone synthesis. Stereoselective fluorination is key to controlling the 2-diastereoselectivity. We also report a substantially improved glycosylation reaction with both the 2-bromo-2-fluoro and 2-chloro-2-fluoro sugars. These improvements allowed us to prepare 2′-dihalo nucleosides 13 and 14 in an overall 15–20% yield.