A facile route to 3′-modified oligonucleotides

We describe an easy method for the solid phase synthesis of 3′-modified oligonucleotides. The general synthetic scheme involves the immobilisation of 5′-DMTr-T to CPG via a sulfonate linker, oligonucleotide synthesis and subsequent basic treatment to afford 3′-modified oligonucleotides containing a 2,3′-anhydronucleoside moiety. These compounds can be readily transformed into 3′-substituted oligonucleotides such as 3′-deoxy-3′-azido species.