Lanthanide‐catalyzed alkynyl exchange through C−C single‐bondcleavage assisted by a secondary amino group is reported. A lanthanide amido complex is proposed as a key intermediate, which undergoes unprecedented reversible β‐alkynyl elimination followed by alkynyl exchange and imine reinsertion. The in situ homo‐ and cross‐dimerization of the liberated alkyne can serve as an additional driving force
Beyond the Limits: Palladium-N-Heterocyclic Carbene-Based Catalytic System Enables Highly Efficient [4+2] Benzannulation Reactions
作者:Olga V. Zatolochnaya、Alexey V. Galenko、Vladimir Gevorgyan
DOI:10.1002/adsc.201100983
日期:2012.4.16
A highlyefficientcatalyticsystem for the palladium‐catalyzed [4+2] benzannulationreaction of enynes and enynophiles has been developed. The use of an N‐heterocyclic carbene‐based palladium precursor allowed us to achieve turnover numbers up to 1800. The new catalyticsystem has enabled an expansion of the scope of the [4+2] homo‐benzannulationreaction.
Piano‐Stool Ruthenium <i>N</i>‐Heterocyclic Carbene Complexes for <i>gem</i>‐Specific Catalytic Dimerization of Terminal Alkynes
作者:Kasumi Hayashi、Qiuming Liang、Franka Philippi、Datong Song
DOI:10.1002/ejic.202300168
日期:2023.7.25
A series of piano-stool Ru-NHC (NHC=N-heterocyclic carbene) complexes with various levels of steric congestion have been used as precatalysts in the catalytic dimerization of terminal alkynes. The most congested complexes of this series give 100 % gem-enyne products at ambient temperature when activated with a base.
Allenyl ketones are widely distributed in various bioactive molecules which lead their selective synthesis continues a hot research topic. Currently, most of the developed protocols require multistep and stoichiometric reactions together with noble metal catalysts. Herein, we developed a practical methodology to access allenyl ketonesstraightforwardlyvia multi-component coupling of 1,3-enynes, fluoroalkyl
烯基酮广泛分布于各种生物活性分子中,这使得其选择性合成仍然是研究的热点。目前,大多数已开发的方案需要与贵金属催化剂一起进行多步和化学计量反应。在此,我们开发了一种实用方法,通过 1,3-烯炔、氟代烷基卤化物、芳基硼酸和 CO 与镍作为催化剂的多组分偶联,直接获得丙二烯基酮。以中等至良好的产率生产了一系列含有丙二烯基酮的氟代烷基单元。这种新方法具有廉价的催化系统、相对温和的反应条件、广泛的底物范围、优异的区域选择性以及所得产物的有吸引力的合成转化。
Cobalt-Catalyzed gem-Cross-Dimerization of Terminal Alkynes
作者:Jia-Feng Chen、Changkun Li
DOI:10.1021/acscatal.9b05078
日期:2020.3.20
Transition-metal-catalyzed dimerization of two different terminalalkynes provides an atom-economic synthesis of valuable conjugated 1,3-enynes. Despite many catalyst systems developed, the state-of-the-art solutions are still limited to special alkynes. A practical catalyst, which could be used to cross-dimerize general aryl alkynes and aliphatic alkynes, is still highly desired. Herein we present