Diastereoselective [4 + 1] Cycloaddition of Alkenyl Propargyl Acetates with CO Catalyzed by [RhCl(CO)2]2
摘要:
A class of alkenyl propargyl acetates, RCH(OAc)C CC(CH3)=CH2 (5), are found to undergo [4 + 1] cycloaddition with CO (1 atm) in the presence of [RhCl(CO)(2)](2) in refluxing 1,2-dichloroethane to give cyclopentenones (6) in good yields. It has been demonstrated that, when the R group of 5 is a phenyl group bearing o-electron-withdrawing substituents up to 10:1 diastereoselectivity and 96% yield can be achieved for the [4 + 1] cycloaddition. This process provides a convenient method to construct highly functionalized cyclopentenones that are useful in organic synthesis.
Gold‐catalyzed [4+2] Annulations of Dienes with Nitrosoarenes as 4 π Donors: Nitroso‐Povarov Reactions
作者:Ching‐Nung Chen、Rai‐Shung Liu
DOI:10.1002/anie.201903615
日期:2019.7.15
This work reports the first success of the nitroso‐Povarov reaction, involving gold‐catalyzed [4+2] annulations of nitrsoarenes with substituted cyclopentadienes. In this catalytic sequence, nitrosoarenes presumably attack gold‐π‐dienes by a 1,4‐addition pathway, generating allylgold nitrosonium intermediates to complete an intramolecular cyclization. Acyclic dienes are also applicable substrates,
Gold‐Catalyzed [3+2]‐Annulations of α‐Aryl Diazoketones with the Tetrasubstituted Alkenes of Cyclopentadienes: High Stereoselectivity and Enantioselectivity
作者:Ching‐Nung Chen、Wei‐Min Cheng、Jian‐Kai Wang、Tzu‐Hsuan Chao、Mu‐Jeng Cheng、Rai‐Shung Liu
DOI:10.1002/anie.202012611
日期:2021.2.23
This work reports gold‐catalyzed [3+2]‐annulations of α‐diazo ketones with highly substituted cyclopentadienes, affording bicyclic 2,3‐dihydrofurans with high regio‐ and stereoselectivity. The reactions highlights the first success of tetrasubstituted alkenes to undergo [3+2]‐annulations with α‐diazo carbonyls. The enantioselective annulations are also achieved with high enantioselectivity using chiral
type of structure units is full of challenge due to their congested chemical environment. Herein, we report a new gold(I) self-relay catalysis merging [3,3]-sigmatropic rearrangement/Nazarov cyclization with allylic alkylation starting from 1,3-enyne acetates and allylic alcohols, producing a wide range of synthetically important allyl cyclopentenones with an all-carbon quaternary stereocenter in good
An efficientsynthetic approach for the synthesis of cyclopentenones containing a C–C stereocenter that relies on gold(I)-catalyzed Nazarov-type cyclization/1,6-addition of 1,3-enyne esters with p-quinone methides (p-QMs) is described. This tandem transformation exhibited a satisfactory substrate scope and passable functional group compatibility, providing a novel protocol for rapid assembly cyclopentenones
一种有效合成含有 C-C 立构中心的环戊烯酮的合成方法,该方法依赖于金 (I) 催化的纳扎罗夫型环化/1,3-烯炔酯与对醌甲基化物的 1,6-加成( p -QMs )进行了描述。这种串联转化表现出令人满意的底物范围和良好的官能团兼容性,为在温和反应条件下以良好至优异的产率快速组装环戊烯酮提供了新的方案。