2290-40-6Relevant academic research and scientific papers
Nickel-Catalyzed Defluorinative Coupling of Aliphatic Aldehydes with Trifluoromethyl Alkenes
Montgomery, John,Xiao, Jichao
, p. 2463 - 2471 (2022/02/17)
A simple procedure is reported for the nickel-catalyzed defluorinative alkylation of unactivated aliphatic aldehydes. The process involves the catalytic reductive union of trifluoromethyl alkenes with aldehydes using a nickel complex of a 6,6′-disubstituted bipyridine ligand with zinc metal as the terminal reductant. The protocol is distinguished by its broad substrate scope, mild conditions, and simple catalytic setup. Reaction outcomes are consistent with the intermediacy of an α-silyloxy(alkyl)nickel intermediate generated by a low-valent nickel catalyst, a silyl electrophile, and the aldehyde substrate. Mechanistic findings with cyclopropanecarboxaldehyde provide insights into the nature of the reactive intermediates and illustrate fundamental reactivity differences that are governed by subtle changes in the ligand and substrate structure.
Cationic Dirhodium Complexes Bridged by 2-Phosphinopyridines Having an Exquisitely Positioned Axial Shielding Group: A Molecular Design for Enhancing the Catalytic Activity of the Dirhodium Core
Ohnishi, Ryuhei,Ohta, Hidetoshi,Mori, Shigeki,Hayashi, Minoru
, p. 2678 - 2690 (2021/07/31)
This report describes a strategy to create highly electrophilic dirhodium catalysts. The electrophilicity of lantern-Type dirhodium complexes is generally decreased by the coordination of a ligand to the axial site, which often causes a reduction in the catalytic activity. We designed and synthesized a series of cationic dirhodium complexes bridged by 2-diarylphosphinopyridines having a bulky 2,4,6-Triisopropylphenyl (Tip) group that can prevent the attack of external molecules to the closest axial site. Theoretical calculations indicated that the Tip group weakly interacts with the axial site but hardly reduces the electrophilicity of the dirhodium core. The complexes served as excellent catalyst precursors for the dehydrogenative silylation of alcohols using hydrosilanes under mild conditions and a low metal loading, producing the silyl ethers in higher yields in comparison to conventional dirhodium complexes.
Chemoselective Deoxygenation of 2° Benzylic Alcohols through a Sequence of Formylation and B(C6F5)3-Catalyzed Reduction
Oestreich, Martin,Richter, Sven C.
supporting information, p. 2103 - 2106 (2021/07/22)
A sequence of formylation and B(C6F5)3-catalyzed reduction of the resulting formate with Et3SiH enables the chemoselective deoxygenation of secondary benzylic alcohols. Primary benzylic and tertiary non-benzylic alcohols are not reduced by this protocol. The formyl group fulfills a double role as activator and self-sacrificing protecting group. The deoxygenation of these formates is fast and can be carried out in the presence of other potentially reducible groups. Neighboring-group participation was found in the deoxygenation of certain diol motifs.
Nickel-catalyzed reductive coupling of unactivated alkyl bromides and aliphatic aldehydes
Cruz, Cole L.,Montgomery, John
, p. 11995 - 12000 (2021/09/28)
A mild, convenient coupling of aliphatic aldehydes and unactivated alkyl bromides has been developed. The catalytic system features the use of a common Ni(ii) precatalyst and a readily available bioxazoline ligand and affords silyl-protected secondary alcohols. The reaction is operationally simple, utilizing Mn as a stoichiometric reductant, and tolerates a wide range of functional groups. The use of 1,5-hexadiene as an additive is an important reaction parameter that provides significant benefits in yield optimizations. Initial mechanistic experiments support a mechanism featuring an alpha-silyloxy Ni species that undergoes formal oxidative addition to the alkyl bromideviaa reductive cross-coupling pathway.
Pd catalysts supported on dual-pore monolithic silica beads for chemoselective hydrogenation under batch and flow reaction conditions
Yamada, Tsuyoshi,Ogawa, Aya,Masuda, Hayato,Teranishi, Wataru,Fujii, Akiko,Park, Kwihwan,Ashikari, Yosuke,Tomiyasu, Noriyuki,Ichikawa, Tomohiro,Miyamoto, Riichi,Bai, Hongzhi,Matsuyama, Kiyoshi,Nagaki, Aiichiro,Sajiki, Hironao
, p. 6359 - 6367 (2020/11/03)
Two different types of palladium catalysts supported on dual-pore monolithic silica beads [5% Pd/SM and 0.25% Pd/SM(sc)] for chemoselective hydrogenation were developed. Alkyne, alkene, azide, and nitro functionalities and the aromatic N-Cbz protecting group were chemoselectively hydrogenated using 5% Pd/SM. On the other hand, 0.25% Pd/SM(sc) showed unique and higher hydrogenation catalyst activity toward a wide variety of reducible functionalities. Furthermore, the catalyst activities of both 5% Pd/SM and 0.25% Pd/SM(sc) under flow hydrogenation conditions were also evaluated. A pre-packed 5% Pd/SM cartridge could be used continuously for at least 72 h without any loss of catalyst activity. The 0.2% Pd/SM(sc) catalyst prepacked in a cartridge showed high catalyst activity for the flow hydrogenation of trisubstituted alkenes under mild reaction conditions. This journal is
Rhenium-Catalyzed Reduction of Carboxylic Acids with Hydrosilanes
Wei, Duo,Buhaibeh, Ruqaya,Canac, Yves,Sortais, Jean-Baptiste
supporting information, p. 7713 - 7716 (2019/10/10)
Re2(CO)10 efficiently catalyzes the direct reduction of various carboxylic acids under mild conditions (rt, irradiation 350 or 395 nm). While aliphatic carboxylic acids were readily converted to the corresponding disilylacetals with low catalyst loading (0.5 mol %) in the presence of Et3SiH (2.2 equiv), aromatic analogues required more drastic conditions (Re2(CO)10 5 mol %, Ph2MeSiH 4.0 equiv) to afford the corresponding aldehydes after acid treatment.
A Versatile Iridium(III) Metallacycle Catalyst for the Effective Hydrosilylation of Carbonyl and Carboxylic Acid Derivatives
Corre, Yann,Rysak, Vincent,Trivelli, Xavier,Agbossou-Niedercorn, Francine,Michon, Christophe
supporting information, p. 4820 - 4826 (2017/09/07)
A versatile iridium(III) metallacycle catalysed rapidly and selectively the reduction of a large array of challenging esters and carboxylic acids as well as various ketones and aldehydes. The reactions proceeded in high yields at room temperature by hydrosilylation followed by desilylation. Although the reactions of various aldehydes and ketones resulted exclusively in alcohols, the hydrosilylation of esters led to alcohols or ethers, depending on the type of substrate. Regarding the carboxylic acids, again the nature of the reagent controlled the outcome of the hydrosilylation reaction, either alcohols or aldehydes being formed.
Development of chelate resin-supported palladium catalysts for chemoselective hydrogenation
Monguchi, Yasunari,Ichikawa, Tomohiro,Nozaki, Kei,Kihara, Kensuke,Yamada, Yuuko,Miyake, Yutaka,Sawama, Yoshinari,Sajiki, Hironao
supporting information, p. 6499 - 6505 (2015/08/18)
Abstract Two kinds of palladium catalysts immobilized on a chelate resin bearing diiminoacetate or polyamine moieties on the polystyrene-divinylbenzene polymer were newly prepared by the adsorption of palladium (II) ions on these resins followed by the reduction to palladium (0) with hydrazine monohydrate. Both catalysts showed a similar activity for hydrogenation. A variety of reducible functionalities, except for benzylic alcohol, alkyl benzyl ether, silyl ether, and epoxide, could be reduced under the hydrogenation conditions using either catalyst. Since the palladium metal elution from the immobilized catalysts was never observed, the catalysts could be reused without any decrease in the catalyst activity for at least 5 runs.
Unique Chemoselective Hydrogenation using a Palladium Catalyst Immobilized on Ceramic
Monguchi, Yasunari,Marumoto, Takahisa,Ichikawa, Tomohiro,Miyake, Yutaka,Nagae, Yoshiyuki,Yoshida, Michiyuki,Oumi, Yasunori,Sawama, Yoshinari,Sajiki, Hironao
, p. 2155 - 2160 (2015/11/24)
A heterogeneous palladium catalyst supported on a ceramic (5 % Pd/ceramic) was developed. The catalyst exhibited a specific chemoselectivity for hydrogenation that has never been achieved by other palladium-catalyzed methods. Either aliphatic or aromatic N-Cbz groups could be deprotected to the corresponding free-amines, while the hydrogenolysis of benzyl esters and ethers did not proceed. Furthermore, aryl chlorides and epoxides were tolerant under the Pd/ceramic-catalyzed hydrogenation conditions. 5 % Pd/ceramic could be reused without any loss of catalyst activity, as no palladium leaching was detected in the reaction media.
Selective reduction of carboxylic acids to aldehydes catalyzed by B(C 6F5)3
Bezier, David,Park, Sehoon,Brookhart, Maurice
supporting information, p. 496 - 499 (2013/03/29)
B(C6F5)3 efficiently catalyzes hydrosilylation of aliphatic and aromatic carboxylic acids to produce disilyl acetals under mild conditions. Catalyst loadings can be as low as 0.05 mol %, and bulky tertiary silanes are favored to give selectively the acetals. Acidic workup of the disilyl acetals results in the formation of aldehydes in good to excellent yields.
