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Synthetic Studies on Nitrogen Containing Natural Products

含氮天然产物的合成研究

基本信息

批准号：
08457582
负责人：
FUKUYAMA Tohru
金额：
$ 4.74万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

In connection with our recent report on the novel use of 2- and 4-nitrobenzenesulfonamide that provides an efficient way for the synthesis of secondary amines, we have developed 2,4-dinitrobenzenesulfonamides amine protective group, which undergo exceptionally facile and selective deprotection in the presence of 2-nitrobenzenzenesulfonamides. Combination of these sulfonamides could be used for the preparation of wide variety of diamines.Using our protocol for the preparation of secondary amines and indole synthesis previously reported, we could achieve highly efficient total syntheses of ((]SY.+-。[))-vincadifformine and (-) -tabersonine. The common 3-indole ethanol part for both total syntheses was prepared from isonitrile, followed by introduction of acrylate moiety on the indole 2-position in one pot. Condensation of the indole part and the amine moiety protected as 2,4-dinitrobenzenesulfonamide under Mitsunobu condition gave cyclization precursors. Removal of Boc protective groups on indole NH and 2,4-dinitrosulfonamide group in mild condition furnished the desired pentacyclic skeletons via dihydrosecodine intermediate. These syntheses represents the most straightforward way to synthesize this class of compounds.Controlling the stereochemistry of the spino-oxiindole moiety remained as a problem in the reported total syntheses of gelsemine by three groups. We could overcome this issue by the introduction of iodine substituent on the oxiindole unit and could achieve stereocontrolled total synthesis of gelsemine in racemic form. Furthermore, the key intermediate in our racemic total synthesis was synthesized as an optically active compound by asymmetric Diels-Alder reaction and Lewis acid mediated rearrangement of epoxybicyclo [2.2.1] heptene system as key reactions.

结合我们最近关于2-和4-硝基苯磺酰胺的新用途的报道，为合成仲胺提供了一条有效的途径，我们开发了2，4-二硝基苯磺酰胺胺保护基团，在2-硝基苯磺酰胺存在下可以进行异常简单和选择性的脱保护。这些磺胺类化合物的组合可用于制备种类繁多的二胺类化合物。利用我们的方法制备仲胺和吲哚合成，我们可以实现高效的(()SY.+-)全合成。[)])-长春花乙双胺和(-)-丹参碱。用于两种全合成的共同的3-吲哚乙醇部分是由异腈制备的，然后在一锅中的吲哚2-位上引入丙烯酸酯部分。吲哚部分与保护为2，4-二硝基苯磺酰胺的胺部分在Mitsunobu条件下缩合得到环化前体。温和条件下去除吲哚氨基和2，4-二硝基磺酰胺基团上的Boc保护基团，可通过二氢叶卡定中间体得到所需的五环骨架。这些合成代表了合成这类化合物的最直接的方法。在已报道的三组钩吻类化合物的全部合成中，控制旋氧吲哚部分的立体化学仍然是一个问题。我们可以通过在氧化吲哚单元上引入碘取代基来克服这个问题，并可以实现外消旋形式的钩吻的立体控制全合成。此外，以不对称Diels-Alder反应和Lewis酸催化的环氧双环[2.2.1]庚烯重排反应为关键反应，合成了外消旋全合成中的关键中间体。