Ka. Tallman et Mm. Greenberg, Oxygen-dependent DNA damage amplification involving 5,6-dihydrothymidin-5-yl in a structurally minimal system, J AM CHEM S, 123(22), 2001, pp. 5181-5187
5,6-Dihydrothymidin-5-yl (1) was independently generated in a dinucleotide
from a phenyl selenide precursor (4). Under free radical chain propagation
conditions, the products-resulting from hydrogen atom donation and radical-
pair reaction are the major observed products in the absence of O-2. The st
ereoselectivity of the trapping process is dependent on the structure of th
e hydrogen-atom donor. No evidence for internucleotidyl hydrogen atom abstr
action by 1 was detected. The tandem lesion (17) resulting from hydrogen at
om abstraction from the Cl ' position of the adjacent 2 ' -deoxyuridine by
the peroxyl radical derived from 1 (3) is observed under aerobic conditions
. The structure of this product is confirmed by independent synthesis and i
ts transformation into a second independently synthesized product (24). Int
ernucleotidyl hydrogen atom abstraction is effected selectively by the SS-d
iastereomer of the peroxyl radical. The formation of dinucleotide 17 provid
es further support for the novel O-2-dependent DNA damage amplification mec
hanism involving 1 reported previously (Greenberg, M. M.; et al. J. Am. Che
m. Sec. 1997, 119, 1828).