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

Abstract

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.

Dehydrogenative (Hetero)arene Alkoxylations Triggered by PdII‐Catalyzed C(sp2)–H Activation and Coordinating Substituent: PdII,III or PdIV Complex as Key Intermediate?

“…ortho ‐Alkoxylation of 9‐butyl‐6‐phenylpurine and 9‐benzyl‐6‐phenylpurine has been performed with Pd(OAc) 2 /PhI(OAc) 2 at 100 °C [Equation ].…”

Benzimidazopurine nucleosides from N6-aryl adenosine derivatives by PhI(OAc)2-mediated C–N bond formation, no metal needed

“…Hydrolysis of the resulting acetate can occur in isolation procedures, as we have previously observed. 25 The resulting 4-hydroxy-1-naphthylamine derivative can then undergo rapid oxidation to iminoquinone 7’ , a structure which would also account for its instability. Support for this pathway can also be obtained in the aromatic acetoxylation observed in PhI(OAc) 2 -mediated cyclizations of N -(biphenyl)pyridin-2-amines.…”

Nucleobases Having M–C Bonds: An Emerging Bio‐Organometallic Field

“…N-directed C-metalation of 9-methyl-6-furylpurine with Pt II , Pd II , and Hg II salts. [18] Scheme 11. In the Pd case, a second metal unit incorporates to the purine ring through the N1 position leading to the dinuclear species 49.…”