Synthesis of the PhIP adduct of 2′-deoxyguanosine and its incorporation into oligomeric DNA

The 2′-deoxyguanosine adduct of the dietary mutagen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) has been synthesized and incorporated into DNA using solid state synthesis technology. The key step to obtaining the C8-dG adduct is a palladium (Xantphos-chelated)-catalyzed N-arylation (Buchwald-Hartwig reaction) of PhIP by a suitably protected 8-bromo-2′-deoxyguanosine derivative. The reaction proceeded in good yield without complicating side products, and the adduct was converted to the required 5′-O-DMT-3′-O-phosphoramidite by standard methods. This modified deoxynucleoside was used to synthesize three oligodeoxynucleotides in which the C8-PhIP-dG adduct was incorporated at a single site. The oligomers were purified by reverse phase HPLC and characterized by mass spectrometry.