Ultraviolet (UV) light damage to DNA1-3 and the corre-sponding enzymatic repair
processes4· 5 have been the subject of much recent attention. This is due, in no small part,
to concerns about the depletion of stratospheric ozone6 and the increase in human skin
cancer projected to result. 7· 8 The most abundant photoproducts from UV irradiation of DNA
are the cis-syn pyrimidine dimers (not shown). 3 Most of the experimental studies in this area
have focused on the formation and repair of this particular lesion. However, more recent …

BARBARA A. SCHWEITZER AND ERIC T. KOOL* Recent X-ray crystallographic and 1H-
NOE data indicate that the stereochemistry of 1 and 2 was incorrectly assigned. Both 1 and 2
as synthesized are in fact R-rather than β-anomers. Compound 3 is correct as shown. The
original assignments were made based on correlation with a published proton NMR
spectrum of a related phenyl nucleoside, and also by correlation of H-1′ coupling constants
to known R-and β-nucleosides. It is now evident that these coupling patterns are generally …