Purinyl N1-Directed Aromatic C–H Oxidation in 6‑Arylpurines and 6‑Arylpurine Nucleosides

Palladium-catalyzed C–H bond
activation and oxidation of
C6 arylpurines as well as C6 arylpurine nucleosides can be accomplished
using Pd­(OAc)2/PhI­(OAc)2 in CH3CN.
Despite the presence of four nitrogen atoms in the purine moiety as
well as the polyoxygenated saccharide and a labile glycosidic bond
in the nucleosides, these reactions can be effectively conducted.
Notably, the generally more labile 2′-deoxyribonucleosides
also undergo reaction. The reaction conditions can be tuned to yield
either monoacetoxylated or diacetoxylated products predominantly.
In the course of these investigations, a dimeric PdII-containing
cyclopalladated C6 naphthylpurine derivative has been obtained and
crystallographically characterized. This compound is competent in
catalyzing the oxidization with PhI­(OAc)2, indicating its
plausible intermediacy in the chemistry. The X-ray structure of a
monoacetoxylated product from this reaction has also been obtained.