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.