Neighboring amide participation in thioether oxidation: relevance to biological oxidation.
To investigate neighboring amide participation in thioether oxidation, which may be relevant to brain oxidative stress accompanying beta-amyloid peptide aggregation, conformationally constrained methylthionorbornyl derivatives with amido moieties were synthesized and characterized, including an X-ray crystallographic study of one of them. Electrochemical oxidation of these compounds, studied by cyclic voltammetry, revealed that their oxidation peak potentials were less positive for those compounds in which neighboring group participation was geometrically possible. Pulse radiolysis studies provided evidence for bond formation between the amide moiety and sulfur on one-electron oxidation in cases where the moieties are juxtaposed. Furthermore, molecular constraints in spiro analogues revealed that S-O bonds are formed on one-electron oxidation. DFT calculations suggest that isomeric sigma*(SO) radicals are formed in these systems.
Glass
Richard S
RS
Department of Chemistry, The University of Arizona, Tucson, Arizona 85721, USA. rglass@u.arizona.edu
Hug
Gordon L
GL
Schöneich
Christian
C
Wilson
George S
GS
Kuznetsova
Larisa
L
Lee
Tang-man
TM
Ammam
Malika
M
Lorance
Edward
E
Nauser
Thomas
T
Nichol
Gary S
GS
Yamamoto
Takuhei
T
D000577:Amides / Q000737:chemistry* / Q000378:metabolism; D000682:Amyloid / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D013440:Sulfides / Q000737:chemistry* / Q000378:metabolism
D000577:Amides; D000682:Amyloid; D013440:Sulfides