Studies Dealing with Thionium Ion Promoted Mannich Cyclization Reactions
作者:Albert Padwa、Alex G. Waterson
DOI:10.1021/jo991414h
日期:2000.1.1
six-membered alkylthio-substituted lactams as transient intermediates. Further reaction of the alkylthio-substituted lactam with DMTSF generates an N-acyliminium ion, which undergoes cyclization with the tethered aromatic ring to produce an azapolycyclic ring system. Related cyclization sequences occur when amido thioacetals possessing simple olefinic tethers were used. The overall procedure represents an efficient
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
Total Syntheses of (±)-β-Erythroidine and (±)-8-oxo-β-Erythroidine by an Intramolecular Diels−Alder Cycloaddition of a 2-Amidoacrolein
作者:Yong He、Raymond L. Funk
DOI:10.1021/ol061267r
日期:2006.8.1
[reaction: see text] The totalsyntheses of (+/-)-beta-erythroidine and (+/-)-8-oxo-beta-erythroidine are described. The tetracyclic ring system of the natural products was quickly assembled by a strategy that features a retrocycloaddition/cycloaddition reaction of an amidodioxin, an intramolecular Heck reaction, and a 6pi-electrocyclic ring closure of a dienoic acid.
[reaction: see text] Radical cyclization of N-allyl-7-bromo-3a-methyl-hexahydroindol-2-one affords a six-membered ring product that prevails over the isomeric five-membered compound. The former product is generated through two reaction pathways: (a) 6-endo-trig ringclosure and (b) rearrangement of an intermediate methylenecyclopentyl radical obtained by 5-exo-trig cyclization.
Copper-Catalyzed Iminoiodane-Mediated Aminolactonization of Olefins: Application to the Synthesis of 5,5-Disubstituted Butyrolactones
作者:Delphine Karila、Loïc Leman、Robert H. Dodd
DOI:10.1021/ol202436a
日期:2011.11.4
A copper(I)-catalyzed reaction of a variety of 4-aryl-pent-4-enoates with nosyliminolodane generated in situ provides the corresponding 5-aryl-5. nosylamidomethylbutyrolactones. The reaction presumably proceeds via an aziridine intermediate, which could be isolated in one case.