1,2-Addition of 3,4-methylenedioxymagnesium bromide to 2-(R) and (S)-benzyloxy-2,5-dihydro-4-furancarboxaldehyde, followed by oxidation, gave the title ketones (3r and 3s). Conjugate addition of the anions of 3,4,5-trimethoxy- and 3,4-methylenedioxybenzaldehyde diphenylthioacetal to 3r and 3s and Raney-nickel desulfurisation, followed by hydrogenolysis under various conditions, gave the title lignans
将1,2-将3,4-亚甲基二氧基
溴化镁加到2-(R)和(S)-苄氧基-2,5-二氢-4-
呋喃甲醛中,然后氧化,得到标题酮(3r和3s)。将3,4,5-
三甲氧基-和3,4-亚甲基二氧基
苯甲醛二苯基
硫缩醛的阴离子共轭添加至3r和3s并进行阮内
镍脱
硫,然后在各种条件下进行氢解,得到标题
木脂素。(-)-Burseran的制备> 98%非对映异构体过量。