Thiation of 2′-deoxy-5,6-dihydropyrimidine nucleosides with Lawesson’s reagent: Characterisation of oxathiaphosphepane intermediates

Abstract

Treatment of 2′-deoxy-3′,5′-dithexyldimethylsilyl-5,6-dihydrouridine with Lawesson’s reagent led to the expected C4-thiolated derivative together with a number of oxathiaphosphepane isomers which resulted from the heat reversible incorporation of an AnPS₂ unit within the 2′-deoxyribose moiety explaining the subsequent anomerisation of the 5,6-dihydropyrimidine nucleosides.