Characterization of 5-hydroxy-8-oxo-7,8-dihydroguanosine in the photosensitized oxidation of 8-oxo-7,8-dihydroguanosine and its rearrangement to spiroiminodihydantoin.
The photosensitized oxidation of 2',3',5'-tris-(O-tert-butyldimethylsilyl)-8-oxo-7,8-dihydroguanosine (8-oxoG) with singlet oxygen was studied by low-temperature NMR. A stable intermediate was characterized at -60 degrees C by (13)C, 2D NMR HMBC spectra, and chemical shifts calculated by hybrid Hartree-Fock density functional theory which agreed with the structure 5-hydroperoxy-8-oxo-7,8-dihydroguanosine. Reduction of this intermediate at low temperature afforded the corresponding alcohol, the long-postulated 5-hydroxy-8-oxo-7,8-dihydroguanosine, the last intermediate in the formation of spiroiminodihydantoin. Upon warming to room temperature, this alcohol rearranges to form the spiroiminodihydantoin in good yield within 2 h.
McCallum
Jeremy E B
JE
Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, CA 90095-1569, USA.
Kuniyoshi
Corrie Y
CY
Foote
Christopher S
CS
D003080:Cold Temperature; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry*; D007700:Kinetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010777:Photochemistry; D013141:Spiro Compounds / Q000737:chemistry*
C496663:5-hydroxy-8-oxo-7,8-dihydroguanosine; D013141:Spiro Compounds; C408822:spiroiminodihydantoin; D006151:Guanosine; C046215:8-hydroxyguanosine