A stereoselective large-scale synthetic process is described to produce 1,3-oxathiolane nucleoside, lamivudine. A mild, inexpensive, and readily available zirconium (IV) chloride (ZrCl4) catalyst acts as a substrate activator for the key N-glycosylation step at room temperature. An optimum of 0.5 equiv of ZrCl4 is required, which gives encouraging results with respect to chemical efficiency and stereoselectivity. The focus of this work was to develop a new Lewis acid catalyst for N-glycosylation reaction that permits mild and selective synthesis of lamivudine at a large scale. It allowed preferential formation of a single isomer of nucleoside out of four possible stereoisomers, starting from the corresponding 1,3-oxathiolane acetate substrate (racemic and/or diastereomeric mixture of isomers). The thermal behavior for the critical N-glycosylation step was also studied by differential scanning calorimetry and reaction calorimetry techniques.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry