STUDIES ON THE PREPARATION OF BIOACTIVE LIGNANS BY OXIDATIVE COUPLINGREACTION .6. OXIDATION OF METHYL (E)-3-(4,5-DIHYDROXY-2-METHOXYPHENYL)-2-BUTENOATE AND LIPID PEROXIDATION-INHIBITORY EFFECTS OF THE PRODUCED CAFFEOQUINONE

Oxidation of hydroxy-alpha-methylcinnamate 5 derived from 4-methylescu letin afforded the alpha-methylcaffeoquinone derivative 7 without form ation of the oxidative coupling product. The reaction of the alpha-met hylferulate derivative 13 afforded a complex mixture of products. Thus , the hydroxy-alpha-methylcinnamates seem not to be suitable substrate s for oxidative coupling. Compound 7 was tested for inhibitory effect on lipid peroxidation. It showed more potent activity than idebenone i n rat brain homogenate,and was much more potent than (+)-alpha-tocophe rol in rat liver microsomes.