The synthesis of unsymmetrical S1-(3′-O-thymidine-O-methanephosphonyl)-S2-p-nitrophenyl disulfides and their reactions with triphenylphosphine

The reaction of thymidine 3′-methanephosphonothioic acid with p-nitrophenylsulfenyl chloride provides S1-(3′-O-thymidine-O-methanephosphonyl)-S2-p-nitrophenyl disulfide which, in the presence of an excess of sulfenyl chloride and triphenylphosphine gives, in a stereospecific manner, thymidine 3′-(S-p-nitrophenyl methanephosphonodithioate).