916987-74-1Relevant academic research and scientific papers
Ruthenium-Catalyzed Reductive Cleavage of Unstrained Aryl-Aryl Bonds: Reaction Development and Mechanistic Study
Zhu, Jun,Chen, Peng-hao,Lu, Gang,Liu, Peng,Dong, Guangbin
supporting information, p. 18630 - 18640 (2019/11/21)
Cleavage of carbon-carbon bonds has been found in some important industrial processes, for example, petroleum cracking, and has inspired development of numerous synthetic methods. However, nonpolar unstrained C(aryl)-C(aryl) bonds remain one of the toughest bonds to be activated. As a detailed study of a fundamental reaction mode, here a full story is described about our development of a Ru-catalyzed reductive cleavage of unstrained C(aryl)-C(aryl) bonds. A wide range of biaryl compounds that contain directing groups (DGs) at 2,2′ positions can serve as effective substrates. Various heterocycles, such as pyridine, quinoline, pyrimidine, and pyrazole, can be employed as DGs. Besides hydrogen gas, other reagents, such as Hantzsch ester, silanes, and alcohols, can be employed as terminal reductants. The reaction is pH neutral and free of oxidants; thus a number of functional groups are tolerated. Notably, a one-pot C-C activation/C-C coupling has been realized. Computational and experimental mechanistic studies indicate that the reaction involves a ruthenium(II) monohydride-mediated C(aryl)-C(aryl) activation and the resting state of the catalyst is a η4-coordinated ruthenium(II) dichloride complex, which could inspire development of other transformations based on this reaction mode.
Direct preparation of carbonatoruthenium(II) derivatives (2) (see abstract) and their use as precursor of the ruthenium dihydride (p-cymene) [PCy(3)] and the [Ru(VI)-arene] (L)[(MeCN)(2)] [[BF(4)](2)] complexes
Demerseman, Bernard,Mbaye, Mbaye Diagne,Semeril, David,Toupet, Loic,Bruneau, Christian,Dixneuf, Pierre H.
, p. 1174 - 1181 (2007/10/03)
[RuCl2(η6-arene)(PR3)] complexes react with K2CO3 in the presence of water to afford the carbonatoruthenium(II) derivatives [Ru(η2-O2CO) (η6-arene)(PR3)] (2; arene = p-cymene, R = Cy, Ph, or Me; arene = hexamethylbenzene, R = Me) involving a planar Ru(η2- O2CO) moiety as shown by X-ray crystal structure determination of 2a (p-cymene, PCy3) and 2d (hexamethylbenzene, PMe3). The complex [Ru(η2-O2CO)(p-cymene)(PCy3)] is cleanly converted in hot methanol into the dihydride (RuH2(p-cymene) (PCy3)]. The related complexes [Ru(η2-O 2CO)(η6-arene)(IMes)] [arene = p-cymene or hexamethylbenzene, IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] are straightforwardly prepared by treating [RuCl2(η6- arene)]2 precursors with 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride and K2CO3 in THF at reflux. The removal of the carbonato ligand from complexes 2 with HBF4 in the presence of acetonitrile leads to the dicationic derivatives [Ru(η6-arene)(L) (MeCN)2][BF4]2 (L = PR3 or IMes). Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
