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 Pd^II-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.