Synthesis and biological evaluation of the L-enantiomer of 2′-deoxy-5-ethyl-4′-thiouridine

Racemic 2′-deoxy-5-ethyl-4′-thiouridine was synthesised utilising the stereoselective iodolactonisation of 3-(tert-butyldimethylsilyl)oxy-N,N-dimethyl-4-pentenamide as the key transformation. The stereo-isomeric mixture of nucleosides was resolved using HPLC on a Chiralcel OJ column. The β- enantiomer showed potent activity against human herpesviruses while the β- was inactive.