Electrophilic-Induced Cyclization Reaction of Hexahydroindolinone Derivatives and Its Application toward the Synthesis of (±)-Erysotramidine
作者:Albert Padwa、Hyoung Ik Lee、Paitoon Rashatasakhon、Mickea Rose
DOI:10.1021/jo048647f
日期:2004.11.1
exclusive product. With this system, initial protonation takes place on the more nucleophilic enol ether π-bond and the resulting carboniumion undergoes a subsequent cyclization with the enamido π-bond to give the observed product. The electrophilic promoted cyclizations were extended to include the related hexahydro[1]pyrindinone and 1H-quinolinone systems. An NBS-promoted intramolecular electrophilic
各种取代的八氢吲哚并[7a,1a]-异喹啉酮的方便合成已通过酸诱导的带有束缚苯乙基的六氢吲哚并酮的环化反应而实现。单个内酰胺非对映异构体的形成是立体电子偏爱芳香环从最受阻的一侧轴向攻击初始形成的N-酰基亚胺离子的结果。额外的实验表明,各种含有束缚的π键的六氢吲哚酮都经历了相关的酸诱导的环化反应。用酸处理3-甲基丁-3-烯基取代的六氢吲哚酮可提供异构体八氢吡啶基[2,1- i]的3:1混合物]吲哚酮类化合物的定量收率接近。有趣的是,密切相关的1-(3-甲氧基丁-3-烯基)-取代的六氢吲哚酮一的环化提供了作为唯一产物的吡咯并[3,2,1- ij ]喹啉酮。利用该系统,在更亲核的烯醇醚π键上发生初始质子化,并且所得的碳离子随后与烯酰胺π键进行环化,从而得到观察到的产物。亲电促进的环化反应扩展到包括相关的六氢[1]吡咯烷酮和1 H-喹啉酮系统。NBS促进1- [2-(3,4-二甲氧基苯基)乙基] -1
A Study of Vinyl Radical Cyclization Using <i>N</i>-Alkenyl-7-bromo-Substituted Hexahydroindolinones
A new method for the synthesis of the octahydropyrrolo[3,2,1-ij]quinoline ringsystem that possesses the characteristic skeleton of the aspidosperma family of alkaloids has been developed. The method utilizes an intramolecularDiels−Alderreaction of an amido-substituted furan across a tethered indole π-bond. To apply this strategy to the synthesis of the indole alkaloid spegazzinidine, it was necessary
已开发出一种新的合成八氢吡咯并[3,2,1- ij ]喹啉环系统的方法,该系统具有生物碱的精孢子家族的特征骨架。该方法利用酰胺基取代的呋喃的分子间Diels-Alder反应穿过拴系的吲哚π键。为了将该策略应用于吲哚生物碱spegazzinidine的合成,有必要解决组装五环骨架的最终D-环的问题。发现N-烯丙基-7-溴-3a-甲基六氢吲哚满酮系统的自由基环化优先导致6-内-trig环化产物,在高稀释条件下可获得最佳收率。六元环化产物通过两个反应路径生成:(a)6-内-trig闭环和(b)重排通过5 -exo-trig环化获得的中间体亚甲基-环戊基。制备了许多含有束缚的烯基的相关的7-溴取代的六氢吲哚酮,发现它们在自由基和钯介导的反应条件下均能有效地环化。用几个N-丁烯基取代的系统进行乙烯基自由基环化,得到6- exo和7- end环化产物的混合物。将乙基取代基引入C的方案还开发了20个位置