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
Efficient Synthesis of (±)-Erysotramidine Using an NBS-Promoted Cyclization Reaction of a Hexahydroindolinone Derivative
作者:Hyoung Ik Lee、Michael P. Cassidy、Paitoon Rashatasakhon、Albert Padwa
DOI:10.1021/ol036106r
日期:2003.12.1
An NBS-promoted intramolecular electrophilic aromatic substitution reaction of a hexahydroindolinone derivative was used to assemble the tetracyclic core of the erythrinane skeleton. The resulting cyclized product was transformed into (+/-)-erysotramidine in three additional steps. The cyclization reaction is also successful using variously substituted aryl and furanyl bicyclic lactams under acidic
Acid-Promoted Cyclization Reactions of Tetrahydroindolinones. Model Studies for Possible Application in a Synthesis of Selaginoidine
作者:Mickea D. Rose、Michael P. Cassidy、Paitoon Rashatasakhon、Albert Padwa
DOI:10.1021/jo0619783
日期:2007.1.1
[GRAPHIC]The synthesis of various substituted bicyclic lactams by an acid-induced Pictet-Spengler reaction of tetrahydroindolinones bearing tethered heteroaromatic rings is presented. The outcome of the cyclization depends on the position of the furan tether, tether length, nature of the tethered heteroaromatic ring, and the substituent group present on the 5-position of the tethered heteroaryl group. A one-pot procedure was developed to efficiently prepare tetrahydroindolinones containing tethered furan rings. In a typical example, the reaction of furanyl azide 26 with n-Bu3P delivered iminophosphorane 27, which was allowed to react with a 1-alkyl-(2-oxocyclohexyl)acetic acid to provide the desired furanyl-substituted tetrahydroindolinone system 29. Treatment of 29 with trifluoroacetic acid afforded the tetracyclic lactam skeleton 30 found in the alkaloid (+/-)-selaginoidine.