A Regiocontrolled Synthesis of N7- and N9-Guanine Nucleosides

Article abstract of DOI:10.1021/jo00241a032

The reaction of 2-O-acetylated and 2-O-benzoylated glycosides 3a,b/4a,b with silylated N²-acetylguanine 7 selectively gave N⁷-guanine nucleosides 8a,b/9a,b under kinetically controlled conditions (SnCl4/CH3CN, room temperature), whereas 2-O-benzoylated glycosides 3b/4b selectively gave isomeric N⁹-guanine nucleosides 10b/11b under termodynamically controlled conditions (TMSOTf/(CH2Cl)2, reflux).Unambiguous assignment of nucleoside structure was accomplished after hydrolysis (NH3/MeOH) of the initial products to the known nucleosides 8c, 9c, 10c, and 11c followed by 1H NMR and 13C NMR spectral analysis.The described procedures provide the best method to date for the selective synthesis of either N⁷- or N⁹-guanine nucleosides from a common substrate.