7614-93-9Relevant academic research and scientific papers
Well-Defined Silica-Supported Tungsten(IV)-Oxo Complex: Olefin Metathesis Activity, Initiation, and Role of Br?nsted Acid Sites
Chan, Ka Wing,Mance, Deni,Safonova, Olga V.,Copéret, Christophe
, p. 18286 - 18292 (2019)
Despite the importance of the heterogeneous tungsten-oxo-based olefin metathesis catalyst (WO3/SiO2) in industry, understanding of its initiation mechanism is still very limited. It has been proposed that reduced W(IV)-oxo surface sp
Syntheses, photophysical properties, and reactivities of novel bichromophoric Pd complexes composed of Ru(ii)-polypyridyl and naphthyl moieties
Murata, Kei,Araki, Mizuki,Inagaki, Akiko,Akita, Munetaka
, p. 6989 - 7001 (2013)
A series of novel bichromophoric Ru(ii) complexes bearing a naphthyl chromophore linked with 2,2′-bipyridyl (bpy) and 2,2′-bipyrimidine (bpm) ligands were synthesized. Complexation with a Pd-alkyl unit led to the formation of bichromophoric Ru-Pd catalyst
Reactive separation of β-bromoethylbenzene from α-β-bromoethylbenzene mixtures: a Zn2+-mediated radical polymerization mechanism
Deng, Tianyu,Tian, Jiaming,Yan, Binhang,Zhu, Junqiu
, p. 1219 - 1222 (2022/02/03)
A Zn2+-induced reactive separation method for the purification of β-bromoethylbenzene from α-β-bromoethylbenzene mixtures is discovered, where the selective decomposition of α-bromoethylbenzene follows a radical mechanism. Zn2+ facilitates the homolysis of the C-Br bond of halohydrocarbons with benzyl bromide, enabling the separation of the corresponding isomers with almost identical physical properties.
Nickel-Catalyzed Arylation of C(sp3)-O Bonds in Allylic Alkyl Ethers with Organoboron Compounds
Li, Xiaowei,Li, Yuxiu,Zhang, Zhong,Shi, Xiaolin,Liu, Ruihua,Wang, Zemin,Li, Xiangqian,Shi, Dayong
, p. 6612 - 6616 (2021/09/02)
A nickel-catalyzed cross-coupling of allylic alkyl ethers with organoboron compounds through the cleavage of the inert C(sp3)-O(alkyl) bonds is described. Several types of allylic alkyl ethers can be coupled with various boronic acids or their derivatives to give the corresponding products in good to excellent yields with wide functional group tolerance and excellent regioselectivity. The gram-scale reaction and late-stage modification of biologically active compounds further prove the practicality of this synthetic method.
Remote Arylative Substitution of Alkenes Possessing an Acetoxy Group via β-Acetoxy Elimination
Kakiuchi, Fumitoshi,Kochi, Takuya,Kumagai, Takaaki,Muto, Kazuma
, p. 24500 - 24504 (2021/10/19)
Palladium-catalyzed remote arylative substitution was achieved for the reaction of arylboronic acids with alkenes possessing a distant acetoxy group to provide arylation products having an alkene moiety at the remote position. The use of β-acetoxy elimination as a key step in the catalytic cycle allowed for regioselective formation of unstabilized alkenes after chain walking. This reaction was applicable to various arylboronic acids as well as alkene substrates.
Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information, p. 16470 - 16485 (2021/10/20)
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Cascade Reductive Friedel-Crafts Alkylation Catalyzed by Robust Iridium(III) Hydride Complexes Containing a Protic Triazolylidene Ligand
Albrecht, Martin,Alshakova, Iryna D.
, p. 8999 - 9007 (2021/07/31)
The synthesis of complex molecules like active pharmaceutical ingredients typically requires multiple single-step reactions, in series or in a modular fashion, with laborious purification and potentially unstable intermediates. Cascade processes offer attractive synthetic remediation as they reduce time, energy, and waste associated with multistep syntheses. For example, triarylmethanes are traditionally prepared via several synthetic steps, and only a handful of cascade routes are known with limitations due to high catalyst loadings. Here, we present an expedient catalytic cascade process to produce triarylmethanes. For this purpose, we have developed a bifunctional iridium system as the efficient catalyst to build heterotriaryl synthons via reductive Friedel-Crafts alkylation from ketones, arenes, and hydrogen. The catalytically active species were generated in situ from a robust triazolyl iridium(III) hydride complex and acid and is composed of a metal-bound hydride and a proximal ligand-bound proton for reversible dihydrogen release. These complexes catalyze the direct hydrogenation of ketones at slow rates followed by dehydration. Appropriate adjustment of the conditions successfully intercepts this dehydration and leads instead to efficient C-C coupling and Friedel-Crafts alkylation. The scope of this cascade process includes a variety of carbonyl substrates such as aldehydes, (alkyl)(aryl)ketones, and diaryl ketones as precursor electrophiles with arenes and heteroarenes for Friedel-Crafts coupling. The reported method has been validated in a swift one-step synthesis of the core structure of a potent antibacterial agent. Excellent yields and exquisite selectivities were achieved for this cascade process with unprecedentedly low iridium loadings (0.02 mol %). Moreover, the catalytic activity of the protic system is significantly higher than that of an N-methylated analogue, confirming the benefit of the Ir-H/N-H hydride-proton system for high catalytic performance.
Enantioselective Hydroalkenylation of Olefins with Enol Sulfonates Enabled by Dual Copper Hydride and Palladium Catalysis
Schuppe, Alexander W.,Knippel, James Levi,Borrajo-Calleja, Gustavo M.,Buchwald, Stephen L.
supporting information, p. 5330 - 5335 (2021/05/04)
The catalytic enantioselective synthesis of α-chiral olefins represents a valuable strategy for rapid generation of structural diversity in divergent syntheses of complex targets. Herein, we report a protocol for the dual CuH- and Pd-catalyzed asymmetric Markovnikov hydroalkenylation of vinyl arenes and the anti-Markovnikov hydroalkenylation of unactivated olefins, in which readily available enol triflates can be utilized as alkenyl coupling partners. This method allowed for the synthesis of diverse α-chiral olefins, including tri- and tetrasubstituted olefin products, which are challenging to prepare by existing approaches.
Preparation and application of triphenylphosphine allyl palladium halide compound and derivative thereof
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Paragraph 0183-0188, (2020/05/30)
The invention discloses a synthesis method of a triphenylphosphine allyl palladium halide compound and a derivative thereof. The synthesis method comprises the step of carrying out one-step reaction on a mixture containing a palladium salt, a halogenated allyl compound and a trisubstituted phosphine compound to obtain the triphenylphosphine allyl palladium halide compound and the derivative thereof. The method is low in cost, high in efficiency, easy to operate and high in safety. The prepared triphenylphosphine allyl palladium halide compound and the derivative thereof can be widely applied as catalysts to catalytic cross coupling or homogeneous coupling reactions of various types of organic substrates so as to prepare various organic reaction intermediates.
In Situ Ring-Closing Strategy for Direct Synthesis of N-Heterocyclic Carbene Nickel Complexes and Their Application in Coupling of Allylic Alcohols with Aryl Boronic Acids
Wang, Yu-Bin,Liu, Bin-Yuan,Bu, Qingqing,Dai, Bin,Liu, Ning
, p. 2930 - 2940 (2020/06/17)
A in situ ring-closing strategy was developed for the synthesis of N-heterocyclic carbene nickel complexes. The process was carried out in air, and did not require solvent purification. The resulting nickel complexes were investigated as catalysts for the coupling of allylic alcohols with aryl boronic acids. A wide range of allylic substrates and aryl acids proved to be applicable to this catalytic system. Control experiments suggest that the Ni(0) may be the true active species in the coupling reactions. (Figure presented.).
