A novel oxidation stage in the chemistry of protoberberine alkaloids. Synthesis of 7,8-dehydroberbines
摘要:
1,2-substituted berbines, such as (-)-caseamine, (-)-caseadine and (-)-O-methylcaseadine, are partially oxidized by iodine to the 7,8-dehydroberbines, while the 2,3-substituted berbines are oxidized all the way to the protoberberinium salts. This different behaviour is interpreted in terms of the preferred cis or trans B/C quinolizidine conformation of the starting berbines.
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。 )。
Abstract (−)-Caseamine was the major alkaloid isolated fromCeratocapnosheterocarpa. Its structure was elucidated by spectroscopic methods and by total s
Quaternary protoberberine alkaloids from Ceratocapnos heterocarpa
作者:Rafael Suau、M. Victoria Silva、María Valpuesta
DOI:10.1016/0031-9422(93)80045-t
日期:1993.9
Three new quaternary protoberberine alkaloids, cis-caseamine N-oxide, cis-caseadine N-oxide and caseadinium chloride were isolated fromCeratocapnosheterocarpa. Their structures and stereochemistry were determined by spectral methods and chemical correlations.