反应详情

1-(3,4-dimethoxyphenyl)-2,3-bis(ethoxycarbonyl)-4-hydroxy-6,7,8-trimethoxynaphthalene obtained in Example 10 is treated with a sodium methoxide solution in the same manner as described in Example 28, whereby 1-(3,4-dimethoxyphenyl)-2-ethoxycarbonyl-3-methoxycarbonyl-4-hydroxy-6,7,8-trimethoxynaphthalene is obtained as colorless prisms.