Studies on the preparation of bioactive lignans by oxidative coupling reaction. V. Oxidative coupling reaction of methyl (E)-3-(2-hydroxyphenyl)propenoate derivatives and lipid peroxidation inhibitory effects of the produced lignans.
The oxidative coupling reactions of 2-hydroxycinnamates were investigated as a continuation of our previous studies on 4-hydroxy derivatives. The reaction of 2-hydroxycinnamate 1 and 2-hydroxy-4-methoxycinnamate 3 with silver oxide afforded polymerized lignin-like products, while that of 2-hydroxy-bis(methoxymethoxy)cinnamates 5 and 6, after acetylation, gave the enol acetates, 8 and 14, of oxotetrahydrobenzoxanthene derivatives, respectively. These two products were also obtained by the oxidation of 5 and 6 with potassium hexacyanoferrate(III). In the reactions of 5 and 6 with iron(III) chloride, the major products were the partially demethoxymethoxylated compounds 9 and 15, respectively. Thus, the course of the reactions in the oxidation of 2-hydroxycinnamates is quite different from that in the case of 4-hydroxy derivatives. The product 8 and the corresponding oxotetrahydrobenzoxanthene derivative were found to show moderate inhibitory effects upon lipid peroxidation.
Maeda
S
S
New Drug Research Laboratories, Kanebo Co., Ltd., Osaka, Japan.
Masuda
H
H
Tokoroyama
T
T
D000818:Animals; D001921:Brain / Q000378:metabolism; D002934:Cinnamates / Q000737:chemistry*; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D017705:Lignans / Q000138:chemical synthesis* / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects*; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats
D002934:Cinnamates; D007202:Indicators and Reagents; D017705:Lignans