Synthesis of phosphorofluoridates and phosphorofluoridothioates via the phosphoramidite approach

Abstract

We present a very efficient synthetic procedure leading to the phosphorofluoridates RO-P(O)(OH)F 1 or phosphorofluoridothioates RO-P(S)(OH)F 2, which is based on the intermediary of fluorophosphoramidites (RO)P(F)NⁱPr₂5 [R = 9-(hydroxyethyloxymethyl)guaninyl), 3′azido-3′deoxythymidinyl, thymidinyl, anhydrothymidinyl, cholesteryl, N⁶-benzoyl-5′-O-(4,4′-dimethoxytrityl)-2′-deoxyadenosinyl]. The activation of the amino group was performed with trimethylchlorosilane (TMCS).