F. Seela et P. Leonard, STUDIES ON THE BASE-PAIRING PROPERTIES OF N-7-(2-DEOXY-BETA-D-ERYTHRO-PENTOFURANOSYL)GUANINE (N(7)G(D)), Helvetica Chimica Acta, 80(4), 1997, pp. 1301-1318
The base-pairing properties of N-7-(2-deoxy-beta-D-erythro-pentofurano
syl) (N(7)G(d); 1) are investigated. The nucleoside 1 was obtained by
nucleobase-anion glycosylation. The glycosylation reaction of various
6-alkoxy-purin-2-amines 3a-i with 3,5-di-O-(4-toluoyl)alpha-D-erythro-
pentofuranosyl chloride (8) was studied. The N-9/N-7-glycosylation rat
io was found to be 1:1 when 6-isopropoxypurin-2-amine (3d) was used, w
hereas 6-(2-methoxyethoxy)purin-2-amine (3i) gave mainly the N-9-nucle
oside (2:1). Oligonucleotides containing compound 1 were prepared by s
olid-phase synthesis and hybridized with complementary strands having
the four conventional nucleosides located opposite to N(7)G(d). Accord
ing to T-m values and enthalpy data of duplex formation, a base pair b
etween N(7)G(d) and dG is suggested. From the possible N(7)G(d).dG bas
e pair motives, Hoogsteen pairing can be excluded as 7-deaza-2'-deoxyg
uanosine forms the same stable base pair with N(7)G(d) as dG.