Deoxyribonucleoside Phosphorodithioates. Preparation of Dinucleoside Phosphorodithioates from Nucleoside Thiophosphoramidites.

Abstract
A series of protected thymidine thiophosphoramidites have been prepared and their properites evaluated. Although less reactive than phosphormadites, thiophosphoramidites with small N-substituents (methyl) are useful synthons for the preparation of nucleoside phosphorodithioates, as demonstrated by the preparation of a thymidine dimer. The coupling reactions are not as clean as those of the analogous phosphoramidites since the alkylthio group is somewhat labile.