Synthetic Transformations of Transient Purinyl Radicals: Formation of Mono- and Diarylated and Heteroarylated Nucleosides

Article abstract of DOI:10.1021/jo00197a003

Photolysis of 2,6-dihalogenated purine nucleosides produced, through cleavage of the carbon-halogen bond, both purin-2-yl and purin-6-yl radicals (or caged radical pairs) which were intercepted by aromatic solvents such as benzene to produce 2-aryl- or 2,6-diarylpurine nucleosides.Heteroarylations and their selectivities involving pyrrole, thiophene, furan, and pyridine systems were als explored.In all cases, except for the "?-deficient" pyridine, the photoinduced heteroarylations were regiospecific and the products photostable.Photoinduced hydration of 2-substituted 6-chloropurine nucleosides provides an excellent approach for the synthesis of uncommon 2-substituted inosine analogues.High-field 13C NMR data suggest that the 2,6-disubstituted purine nucleosides prefer the anti conformation in solution.