Stereocontrolled synthesis of H-phosphonate DNA.

Abstract

Stereocontrolled synthesis of H-phosphonate DNA by an oxazaphospholidine approach is described. Diastereopure 2'-deoxynucleoside 3'-oxazaphospholidine monomers having two substituents at the 5-position of the oxazaphospholidine ring were allowed to condense with the 5'-hydroxy group of nucleosides in the presence of a less-nucleophilic acidic activator to afford the diastereopure dinucleoside phosphite intermediates. Upon treatment with an anhydrous acid, the phosphite intermediates were stereospecifically converted into the diastereopure dinucleoside H-phosphonates. The method was applied to the solid-phase synthesis of stereoregulated H-phosphonate DNA oligomers containing four kinds of nucleobases.