Rhodium Dinaphthocyclooctatetraene Complexes: Synthesis, Characterization and Catalytic Activity in [5+2] Cycloadditions
作者:Paul A. Wender、Adam B. Lesser、Lauren E. Sirois
DOI:10.1002/anie.201108270
日期:2012.3.12
Rh COT in the act: A Ni0‐catalyzed [2+2+2+2] cycloaddition provides a high‐yielding, scalable synthesis of the ligand dinaphtho[a,e]cyclooctatetraene (dnCOT). dnCOT complexation with RhI gives [Rh(dnCOT)(MeCN)2]SbF6 (see scheme), an excellent catalyst for [5+2] cycloadditions of vinylcyclopropanes and π‐systems with impressive functional group compatibility.
see text] A 2-(2,6-diisopropylphenyl)iminomethylpyridine (1a)/CoCl(2).6H(2)O/Zn reagent has been developed as an effective instant catalyst for the intra- and intermolecular cyclotrimerization of alkynes to substituted benzenes, making the method extremely practical since the reagent, 1a/CoCl(2).6H(2)O/Zn, is inexpensive and easy to handle and the reaction is less sensitive to moisture and is reasonably
Cobalt cyclopentadienyl complexes incorporating a fumarate and a CO ligand (see picture) efficiently catalyze inter‐ and intramolecular [2+2+2] cycloadditions of alkynes, nitriles, and/or alkenes to give benzenes, pyridines, or 1,3‐cyclohexadienes. Unlike catalysts such as [CpCo(CO)2] or [CpCo(C2H4)2] (Cp=C5H5), they are air‐stable, easy to handle, compatible with microwave conditions, and do not necessarily
结合富马酸酯和CO配体的环戊二烯钴复合物(见图)有效地催化炔烃,腈和/或烯烃的分子间和分子内[2 + 2 + 2]环加成反应,从而生成苯,吡啶或1,3-环己二烯。与[CpCo(CO)2 ]或[CpCo(C 2 H 4)2 ](Cp = C 5 H 5)等催化剂不同,它们具有空气稳定性,易于处理,与微波条件兼容,并且不一定需要辐射才能活跃。
Iron-Catalyzed Cyclotrimerization of Terminal Alkynes by Dual Catalyst Activation in the Absence of Reductants
作者:Davide Brenna、Matteo Villa、Tim N. Gieshoff、Fabian Fischer、Marko Hapke、Axel Jacobi von Wangelin
DOI:10.1002/anie.201705087
日期:2017.7.10
metals under mild conditions is at the heart of sustainable synthesis. The cyclotrimerization of alkynes is a valuable atom‐efficient reaction in organic synthesis that is enabled by several metal catalysts, including iron. This study reports an effective iron‐catalyzed cyclotrimerization for the regioselective synthesis of 1,2,4‐substituted arenes (1 mol % catalyst, toluene, 20 °C, 5 min). A dual activation