Synthesis and biological evaluation of novel thionucleosides

The search for novel nucleosides has been a major research focus in medicinal chemistry for several decades, particularly given their proven track record in the treatment of viral infections and cancer. As bioisosteres of natural nucleosides, thionucleosides are especially attractive targets as they often display improved biological activity. Furthermore, the replacement of oxygen with sulfur may sometimes be accompanied by interesting changes in pharmacological effect. This update covers recent advances in the preparation of novel thionucleosides, grouped by synthetic strategy. The biological properties of the target thionucleosides are also summarised, in addition to any reported structure activity relation-ships.