TY - JOUR
T1 - On the reactions of superoxide with keto enols, aci-reductones and ascorbic acid derivatives
AU - Frimer, Aryeh A.
AU - Marks, Vered
AU - Gilinsky-sharon, Pessia
PY - 1991
Y1 - 1991
N2 - The superoxide-mediated base catalyzed autoxidation of αoxo enols is initiated by the dcprotonation of the labile hydoxyl group. Thus, the reaction of O-2 (generated from KO 2/ crown ether in aprotic media) with 3-hydroxycoumarin (I). followed by a CH,I-workup, generates products 24 via a deprotonation-oxidation sequence complicated by a competing saponification of the lactone linkage. The related coumarin reductone (αoxo enediol) 8 is rapidly oxidized by O-2, HO- and t-butoxide to the corresponding triketone, which in turn undergoes further oxidation and rearrangenlent ultimately yielding (upon methyl iodide workup) products 9-14. Whcn the O-2 mediated oxidation is carried out under argon in completely degassed solutions, large amounts (≥ 20% of monodeprotonation product (detected as 9) accumulate. These results are discussed in light of the differing mechanisms proposed by Sawyer and Afanas'ev for the interaction of O-2 with the reductone ascorbic acid.
AB - The superoxide-mediated base catalyzed autoxidation of αoxo enols is initiated by the dcprotonation of the labile hydoxyl group. Thus, the reaction of O-2 (generated from KO 2/ crown ether in aprotic media) with 3-hydroxycoumarin (I). followed by a CH,I-workup, generates products 24 via a deprotonation-oxidation sequence complicated by a competing saponification of the lactone linkage. The related coumarin reductone (αoxo enediol) 8 is rapidly oxidized by O-2, HO- and t-butoxide to the corresponding triketone, which in turn undergoes further oxidation and rearrangenlent ultimately yielding (upon methyl iodide workup) products 9-14. Whcn the O-2 mediated oxidation is carried out under argon in completely degassed solutions, large amounts (≥ 20% of monodeprotonation product (detected as 9) accumulate. These results are discussed in light of the differing mechanisms proposed by Sawyer and Afanas'ev for the interaction of O-2 with the reductone ascorbic acid.
KW - 3-hydroxcoumarin
KW - Ascorbic acid derivatives
KW - Keto enols. reductones
KW - Superoxide mediated oxidation
UR - http://www.scopus.com/inward/record.url?scp=0025985073&partnerID=8YFLogxK
U2 - 10.3109/10715769109145772
DO - 10.3109/10715769109145772
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
C2 - 1649108
AN - SCOPUS:0025985073
SN - 1071-5762
VL - 12
SP - 93
EP - 98
JO - Free Radical Research
JF - Free Radical Research
IS - 1
ER -