title: Theoretical and experimental investigations on the chemical reactions of positively charged phenyl radicals with cytosine and 1-methylcytosine.
abstract: The chemical behavior of positively charged phenyl radicals toward cytosine, 1-methylcytosine, and some pyrimidine analogues in the gas phase was investigated both theoretically by performing molecular orbital calculations and experimentally by using FT/ICR mass spectrometry. The phenyl radicals react with cytosine and 1-methylcytosine predominately by hydrogen abstraction and addition. For cytosine, the preferred site for hydrogen abstraction appears to be the amino group, and addition occurs preferentially at the N3 and N1 positions of the keto and enol tautomeric forms, respectively. For 1-methylcytosine, the methyl group is the thermodynamically favored site for hydrogen abstraction and N3 for addition. Possible structures and formation mechanisms are suggested for two unknown product ions formed upon the reaction of cytosine with the 3-dehydro-N-phenylpyridinium radical cation.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA.
authors.forename: Yiqun
authors.initials: Y
authors.lastname: Huang
authors.forename: Hilkka
authors.initials: H
authors.lastname: Kenttämaa
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D003596:Cytosine / Q000031:analogs & derivatives* / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D008958:Models, Molecular; D011726:Pyridinium Compounds / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D001555:Benzene Derivatives; D005609:Free Radicals; D011726:Pyridinium Compounds; C031532:1-methylcytosine; D003596:Cytosine