Synthesis of (S)-1-(2',3'-dihydroxypropyl)-2-alkylthiouracils as new antiviral agents

2-Alkylthiouracils 1a-f have been prepared. Nucleoside coupling of 2 with sodium salt of 1a-f gave the corresponding dioxolane derivatives 3a-f which were treated with 80% acetic acid at reflux temperature to give (S)-1-(2',3'-dihydroxypropyl)-2-alkylthiouracil derivatives 4a-f. Treatment of 4d with 1 mol tosyl chloride gives the corresponding monotosylate 5. On the other hand, with 2 mol it gives the ditosylate 6. Treatment of 5 and/or 6 with sodium azide/dimethylformamide give 7 and 8 which could be reduced to the corresponding amino derivatives 9 and 10 by using triphenylphosphine/pyridine.