SYNTHESIS OF OLIGONUCLEOTIDES CONTAINING SITE-SPECIFIC CARCINOGEN ADDUCTS - PREPARATION OF THE 2-CYANOETHYL N,N-DIISOPROPYLPHOSPHORAMIDITE OF N-(2'-DEOXYGUANOSIN-8-YL)-2-(ACETYLAMINO)FLUORENE WITH FMOC AS THE BASE-PROTECTING GROUP

A 9-fluorenylmethoxycarbonyl (Fmoc) group was used to protect the exoc yclic amine on the modified guanine of N-(2'-deoxyguanosin-8-yl)-2-(ac etylamino)fluorene (dG-C-8-AAF) so that oligonucleotides containing a site-specific AAF adduct could be prepared. Reaction of Fmoc-Cl with d G-C-8-AAF gave yl)-2'-deoxyguanosin-8-yl]-2-(acetylamino)fluorene (N2- Fmoc-dG- and yl)-2'-deoxyguanosin-8-yl]-2-(acetylamino)fluorene (O-6-F moc-dG-C-8-AAF). The 5'-OH of N-2-FmoodG-C-8-AAF was protected using 4 ,4'-dimethoxrytrityl chloride to yield 5/-Dh4T-N-2-Fmoc-dG-C-8-AAF whi ch was then reacted with 2-cyanoethyl N,N,N',N'-tetraisopropylphosphor odiamidite to obtain the corresponding phosphoramidite. The phosphoram idites of Fmoc-protected dA, dC and dG were also prepared similarly. T he stability of Fmoc-protected C-8-AAF-modified deoxyguanosine was stu died under different conditions to establish the utility of the prepar ed phosphoramidite in solid-phase DNA synthesis.