Novel unique activating reagents in synthesis of biophosphates via phosphoroamidite route

Trimethylhalogenosilanes Me3SiX (X=Cl,Br) are remarkably efficient activators in the reaction of P(III) amidites with nucleosides and other alcohols of biological interest to give P(III) esters in excellent yield. This activation is illustrated by synthesis of P(III) compounds containing a phosphorus-fluorine bond. Under specially chosen conditions the interaction between trimethylhalogenosilanes, 2'-deoxy-nucleosidylphosphoroamidites and nucleosides allows synthesis of 5'-phosphonate -linked deoxydinucleotides. 2,4-Dinitrophenol is an effective activator in “amidite” coupling.