γ‐di‐aryl propanones. The salient feature of this strategy involves the sequential hydride transfer, regiospecific condensation, regiospecific dearylation, and aromatization under metal‐free reaction conditions. The synthesis of unsymmetricallysubstituted triphenylenes by oxidative coupling of the synthesized 1,2,4‐triaryl benzenes has also been demonstrated.
Efficient Intermolecular [2 + 2 + 2] Alkyne Cyclotrimerization in Aqueous Medium Using a Ruthenium(IV) Precatalyst
作者:Victorio Cadierno、Sergio E. García-Garrido、José Gimeno
DOI:10.1021/ja066552k
日期:2006.11.1
bis(allyl)-ruthenium(IV) complex [Ru(eta3:eta3-C10H16)(mu-Cl)Cl}2] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl) was found to catalyze efficiently the [2 + 2 + 2] cyclization of terminal and internal alkynes in aqueous medium.
Cyclotrimerization of terminal alkynes catalyzed by the system of NiCl2/Zn and (benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines
作者:Chanjuan Xi、Zelin Sun、Yongbing Liu
DOI:10.1039/c3dt51674a
日期:——
An effective regioselective cyclotrimerization of terminal alkynes is achieved by the direct utilization of NiCl2·6H2O, Zn, and 2-(benzimidazolyl)-6-(1-(arylimino)ethyl)pyridine in one step under ambient temperature.
Cobalt-catalyzed alkyne cyclotrimerization and crossed [2 + 2 + 2] cycloadditions are developed in a plug flow reactor. The protocol generally uses 5 mol % of Co2(CO)8 and is scalable at least at multigram scale. Efficient and scalable use of Co2(CO)8 for crossed reactions of diynes and alkynes has hardly any precedent.
Combined Photoredox and Iron Catalysis for the Cyclotrimerization of Alkynes
作者:Michael Neumeier、Uttam Chakraborty、Dieter Schaarschmidt、Victor Pena O'Shea、Raul Perez‐Ruiz、Axel Jacobi von Wangelin
DOI:10.1002/anie.202000907
日期:2020.8.3
combinations of visible‐light photocatalysis with metal catalysis have recently enabled the development of hitherto unknown chemical reactions. Dual mechanisms from merging metal‐free photocatalysts and earth‐abundant metal catalysts are still in their infancy. We report a photo‐organo‐iron‐catalyzed cyclotrimerization of alkynes by photoredox activation of a ligand‐free Fe catalyst. The reaction operates