Synthesis of the alkaloids escholamine and takatonine via a modified pomeranz–fritsch reaction
作者:Anthony J. Birch、Anthony H. Jackson、Patrick V. R. Shannon
DOI:10.1039/p19740002190
日期:——
7-Methylenedioxy-1-(3,4-methylenedioxybenzyl)isoquinoline (10)(escholamine free base) was prepared from 6,7-methylenedioxyisoquinoline and 3,4-methylenedioxybenzyl chloride via a Reissert compound in 60% yield. Similarly 5,6,7-trimethoxyisoquinoline and p-methoxybenzyl chloride gave 5,6,7-trimethoxy-1-(4-methoxybenzyl)isoquinoline (11)(takatonine free base) in 75% yield.
用苄基氯化镁处理由胡椒醛和氨基乙醛二甲基乙缩醛形成的席夫碱,得到1-(3,4-亚甲基二氧苯基)-2-苯基乙基氨基乙醛二甲基乙缩醛(4; R 1 = R 2 = H),将其甲苯磺酸酯在下环化。在酸性条件下为1-苄基-1,2-二氢-6,7-亚甲基二氧基-2-甲苯基喹啉(5; R = H)和反式-3,4-亚甲基二氧基sti (6)。进一步的酸处理(5; R = H)得到1-苄基-6,7-亚甲基二氧基异喹啉(7; R = H)和6,7-亚甲基二氧基异喹啉。使用p获得相似的结果-具有相同席夫碱(来自胡椒醛)的-甲氧基苄基氯化镁。通过Reissert化合物由6,7-亚甲基二氧基异喹啉和3,4-亚甲基二氧基苄基氯经Reissert化合物制备6,7-亚甲基二氧基-1-(3,4-亚甲基二氧基苄基)异喹啉(10)(escholamine游离碱),收率为60%。类似地,5,6,7-三甲氧基异喹啉和对甲氧基苄基氯以55%的收率得到5