N2-(p-n-Butylphenyl)-2'-deoxyguanosine (BuPdG) and its 5'-triphosphate (BuPdGTP), expected to be inhibitors of eukaryotic DNA polymerase alpha, have been synthesized. BuPdG was synthesized by two methods and characterized by 1H NMR and by chemical relation to guanosine. Direct synthesis involving silylated N2-(p-n-butylphenyl)guanine (BuPG) and 1-chloro-3,5-di-p-toluoyl-2-deoxyribofuranose in the presence of trimethylsilyl trifluoromethanesulfonate gave one alpha and two beta isomers of deoxyribonucleoside as determined by 1H NMR. However, NMR and UV spectra were equivocal in distinguishing between 7 and 9 isomers. The identity of the desired 9-beta-BuPdG was ultimately proved by its independent synthesis from the corresponding ribonucleoside. 1H NMR spectra of the O'-acetylated ribonucleosides of BuPG showed characteristic patterns of O'-acetylated guanosines, and their identity was proved by relating the products of the reaction of isomeric O'-acetylated 2-bromoinosines with p-n-butylaniline and with ammonia: the 2-bromoinosine which gave guanosine also gave the suspected 9-beta-ribonucleoside, BuPGr, and that which gave N7-beta-ribofuranosylguanine also gave the 7-beta isomer of BuPGr. BuPGr was transformed in a multistep procedure to give BuPdG, identical with the major beta isomer obtained by direct deoxynucleoside synthesis. The 5'-monophosphate of BuPdG was obtained by treatment of the nucleoside with phosphoryl chloride in trimethyl phosphate; the monophosphate reacted as the phosphoimidazolyl derivative with pyrophosphate to yield the 5'-triphosphate, BuPdGTP.(ABSTRACT TRUNCATED AT 250 WORDS)