油脂の酸化防止に関する研究 : (第12報) ω-Bis-(3, 4-dihydroxyphenyl) Alkane類の合成(補遺)

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In the previous paper(1)(2) it was reported that some of the ω, ω-bis-(3, 4-dihydroxyphenyl) alkanes showed remarkable antioxidant activites equal or superior to that of NDGA. Therefore, in the present paper syntheses of ω, ω-bis-(3, 4-dihydroxyphenyl) butane and hexane were exa-mined from the practical standpoint. (1) the preparation of 1, 4-bis-(3, 4-dihydroxyphenyl) butane. The. synthetic method of ω, ω-bis-(3, 4-dihydroxyphenyl) butane described in the previous paper(3) was so complicated that the examination of alternative processes seemed to be necessary. Firstly, ω-bromoacetoveratrone was treated with aqueous KOH in ethanol to yield 1, 2-diverat-roylethylene according to the BOGOSLOVSKIIs method(4), but this attempt was unsuccessful. Then, the method of LUTL(7) to give 1, 2-dibenzoylethylene by the condensation/of benzene and fumaryl chloride was applied for veratrol but the corresponding dibenzoylethylene was not obtained. Next, in order to prepare 1, 4-diveratrylbutane via 1, 2-diveratroylethane, ω-bromoace-toveratrone was converted into car-cyanoacetoveratrone, m.p. 137_??_138° and the both compounds were condensed to give 1-cyano-1, 2-diveratroylethane, m.p. 148_??_149°, but the yield of the first step was so low such as 36% that this method should also be given up. Finaly, the processes from vsratrol and succinic anhydride to yield 1, 4-diveratrylbutane reported in the previous paper(3) were re-examined and the following results were obtained. The yield of 1-veratroyl-3-(3.4-dimethoxy-6-bromophenyl) propane from γ-(3, 4-dimethoxy-6-bromophenyl) butyric acid was found to increase from 13% to 60% when the chloroform solution of the latter compound was treated with SOCl2 in the presence of a trace of-dry pyridine. Then, 1, 4-diveratrylbutane was obtained in 90% yield by hydrogenating 1-veratryl-4-(3, 4-dimethoxy-6-bromophenyl) butane with Raney Ni and KOH in ethanol at 12 atm. and 63°. (2) The preparation of 1, 6-bis-(3, 4-dihydroxyphenyl) hexane. In this series, the ruduction of 1, 4-diveratroylbutane was found to be the most difficult step as was described in the previous paper(3) but it was solved by the following method. 1, 4-Di-veratroylbutane was hydrogenated to give 1, 6-diveratrylhexane with Pd-charcoal in ethanol-acetic acid at atmospheric pressure and room temperature., in the theoretical yield. Also with Cu-CrO in ethanol at 160° for 4 hrs with an initial pressure 40 atm. in 70% yield. 1, 6-Bis-(3, 4-dihydroxyphenyl) hexane was obtained by refluting 1, 6-diveratrylhexane with powdered AlCl3 in anhydrous chlorobenzene for 4 hrs at 140_??_150°. The authors wish to express their appreciation to Professor Dr. Y. SUMIKI for his guidance and advice
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油脂の酸化防止に関する研究 : (第12報) ω-Bis-(3, 4-dihydroxyphenyl) Alkane類の合成(補遺)

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