Aryl H-phosphonates. 12. Synthetic and P-31 NMR studies on the preparationof nucleoside H-phosphonothioate and nucleoside H-phosphonodithioate monoesters

Transformation of nucleoside H-phosphonate monoesters into the correspondin g H-phosphonothioate and X-phosphonodithioate derivatives and possible side -reactions that may accompany this process were studied using P-31 NMR spec troscopy. These provided new insight into a possible mechanism involved in this transformation and constituted the basis for development of efficient methods for the preparation of nucleoside H-phosphonothioate and nucleoside H-phosphonodithioate monoesters using readily available H-phosphonate mono esters as starting materials.