Total Synthesis of the Ortho-Hydroxylated Protoberberines (<i>S</i>)-Govaniadine, (<i>S</i>)-Caseamine, and (<i>S</i>)-Clarkeanidine via a Solvent-Directed Pictet–Spengler Reaction
作者:Brendan Horst、Martin J. Wanner、Steen Ingemann Jørgensen、Henk Hiemstra、Jan H. van Maarseveen
DOI:10.1021/acs.joc.8b02378
日期:2018.12.21
Pictet–Spengler reactions with dopamine derivatives is redirected to the ortho position by a simple change of solvents. In combination with a chiral auxiliary on nitrogen, this ortho-selective Pictet–Spengler produced the 1-benzyltetrahydroisoquinoline alkaloids (S)-crassifoline and (S)-norcrassifoline and the bioactive 1,2-dioxygenated tetrahydroprotoberberine alkaloids (S)-govaniadine, (S)-caseamine,
在Pictet-Spengler反应中与多巴胺衍生物共同的对位选择性通过简单地改变溶剂即可重新定向到邻位。在与手性助剂在氮上,此邻选择性的Pictet-格勒产生的1-benzyltetrahydroisoquinoline生物碱(组合小号)-crassifoline和(小号)-norcrassifoline和生物活性1,2-二氧化tetrahydroprotoberberine生物碱(小号)-govaniadine,(S)-酪胺和(S)-对映体纯度高的克拉酮胺。在B环形成过程中,邻/对比率高达89:19,非对映异构比率高达85:15。酪蛋白胺(三氟乙醇中o / p = 14:86)和克拉酮丁(甲苯中o / p = 86:14)的C环形成所需要的第二次Pictet-Spengler反应证明了这种溶剂导向的区域选择性的一般适用性。 )。