One-Pot Synthesis of Dinucleoside (3,5)-Methylphosphonothioates and their Seleno Congeners via the Phosphonotriazolidite Approach

An efficient method for large laboratory scale synthesis of dinucleoside (3ʹ,5ʹ)-methylphosphonothioates and their methylphosphonoselenoate congeners is presented. Bis-(1,2,4-tri­azoloyl)methylphosphonite generated in situ from methyldichlorophosphine is used as a phosphitylating agent and the preparations are performed as onepot-reactions without isolation of the reactive PIII intermediates.