Synthesis of oligonucleotides containing bulky adducts at guanine N2 via the phosphoramidite of O2-triflate-O6-NPE 2′-deoxyxanthosine

Oligodeoxynucleotides bearing bulky adducts at guanine N2 have been prepared by a postoligomerization strategy in which oligonucleotides containing a highly reactive O2-trifluoromethanesulfonyl-O6-(p-nitrophenethyl) 2′-deoxyxanthosine residue were reacted with (±)-10β-amino-7,8,9,10-tetrahydro-benzo[a]pyrene-7β,8α,9α-triol and related compounds.