Nucleoside H-Phosphonates. 13. Studies on 3H-1,2-Benzodithiol-3-one Derivatives as Sulfurizing Reagents for H-Phosphonate and H-Phosphonothioate Diesters

Article abstract of DOI:10.1021/jo00017a033

Formation of O-oxidized products during sulfurization of H-phosphonothioate and H-phosphonate diesters with 3H-1,2-benzodithiol-3-one 1,1-dioxide (1) was found to be due to generation of the O-oxidizing agents, most likely 3H-2,1-benzoxathiol-3-one 1-oxide (4) and 3H-2,1-benzoxathiol-3-one (5), during the course of the reactions.Another source of the side products formation may be the disproportionation of 1 that occurs in the presence of triethylamine.To overcome these problems, a new sulfur-transferring reagent, 3H-1,2-benzodithiol-3-one (3), has been developed.Under aqueous reaction conditions, which are compartible with both solution and solid-phase synthesis of oligonucleotides, the reagent 3 furnished clean and fast conversion of H-phosphonothioate and H-phosphonate diesters into the corresponding phosphorodi- and phosphoromonothioates.