Post-synthetic introduction of labile functionalities onto purine residues via 6-methylthiopurines in oligodeoxyribonucleotides

Two methods are described for the preparation of oligodeoxynucleotides containing 6-methylthiopurine residues. 6-Methylthiopurine phosphoramidite (6) has been prepared and incorporated into oligomers. Methylation with methyl iodide of 6-thiopurine (or 6-thioguanine) in oligomers also exclusively produces oligomers containing 6-methylthiopurine (or 6-methylthioguanine). The methylthio group at defined purine residues in the deprotected oligomers can be oxidized selectively and converted at the final step into various functional groups including radioactive S-35-thio group, a useful tag for cross-linking studies. Copyright (C) 1996 Elsevier Science Ltd