title: N-oxides of adenosine-type nucleosides undergo pyrimidine ring opening and closure to give 5-amino-4-(1,2,4-oxadiazol-3-yl)imidazole derivatives.
abstract: Treatment of acylated adenosine N-oxides with carboxylic anhydrides and thiophenol resulted in pyrimidine ring opening followed by exocyclic ring closure. Ammonolysis gave 5-amino-4-(5-substituted-1,2,4-oxadiazol-3-yl)-1-(beta-d-ribofuranosyl)imidazole derivatives, whereas iodine in methanol selectively unmasked the 5-amino group. Related flexible nucleoside analogues can be prepared from adenine-type precursors.
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602-5700, USA.
authors.forename: Ireneusz
authors.initials: I
authors.lastname: Nowak
authors.forename: John F
authors.initials: JF
authors.lastname: Cannon
authors.forename: Morris J
authors.initials: MJ
authors.lastname: Robins
mesh_terms: D000241:Adenosine / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D007093:Imidazoles / Q000737:chemistry*; D008958:Models, Molecular; D009705:Nucleosides / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*
chemical_list: D007093:Imidazoles; D009705:Nucleosides; D010087:Oxides; D000241:Adenosine