Synthesis and Characterization of Oligonucleotides Containing 2′-Deoxyxanthosine Using Phosphoramidite Chemistry

Abstract

Oligodeoxynucleotides containing 2′-deoxyxanthosine (Xd) were synthesized in good yield from a O2,O6-bis[2-(4-nitrophenyl)ethyl](NPE)-protected phosphoramidite of Xd. Attempts to synthesize a O6-monoNPE-protected phosphoramidite resulted in formation of a major by-product. The NPE protecting groups were removed by treatment with oximate ion after other protecting groups were removed with aqueous NH4OH solution. The composition of the synthetic oligonucleotides was verified by enzymatic degradation and MALDI-TOF mass spectrometry. The efficacy of this procedure allowed isolation of oligodeoxynucleotides containing multiple Xd residues.