4179-10-6Relevant academic research and scientific papers
Catalytic Hydrogenations with Cationic Heteroleptic Copper(I)/N-Heterocyclic Carbene Complexes
Thiel, Niklas O.,Brechmann, Lea T.,Teichert, Johannes F.
, p. 783 - 787 (2019)
A new heteroleptic cationic copper(I) complex bearing two N-heterocyclic carbene (NHC) ligands has been prepared. In situ, a Cu-O bond can be generated which enables the complex to catalytically activate H 2. The resulting complex shows activit
Visible-Light-Enhanced Cobalt-Catalyzed Hydrogenation: Switchable Catalysis Enabled by Divergence between Thermal and Photochemical Pathways
Mendelsohn, Lauren N.,MacNeil, Connor S.,Tian, Lei,Park, Yoonsu,Scholes, Gregory D.,Chirik, Paul J.
, p. 1351 - 1360 (2021/02/01)
The catalytic hydrogenation activity of the readily prepared, coordinatively saturated cobalt(I) precatalyst, (R,R)-(iPrDuPhos)Co(CO)2H ((R,R)-iPrDuPhos = (+)-1,2-bis[(2R,5R)-2,5-diisopropylphospholano]benzene), is described. While efficient turnover was observed with a range of alkenes upon heating to 100 °C, the catalytic performance of the cobalt catalyst was markedly enhanced upon irradiation with blue light at 35 °C. This improved reactivity enabled hydrogenation of terminal, di-, and trisubstituted alkenes, alkynes, and carbonyl compounds. A combination of deuterium labeling studies, hydrogenation of alkenes containing radical clocks, and experiments probing relative rates supports a hydrogen atom transfer pathway under thermal conditions that is enabled by a relatively weak cobalt-hydrogen bond of 54 kcal/mol. In contrast, data for the photocatalytic reactions support light-induced dissociation of a carbonyl ligand followed by a coordination-insertion sequence where the product is released by combination of a cobalt alkyl intermediate with the starting hydride, (R,R)-(iPrDuPhos)Co(CO)2H. These results demonstrate the versatility of catalysis with Earth-abundant metals as pathways involving open-versus closed-shell intermediates can be switched by the energy source.
Indene Derived Phosphorus-Thioether Ligands for the Ir-Catalyzed Asymmetric Hydrogenation of Olefins with Diverse Substitution Patterns and Different Functional Groups
Margalef, Jèssica,Biosca, Maria,de la Cruz-Sánchez, Pol,Caldentey, Xisco,Rodríguez-Escrich, Carles,Pàmies, Oscar,Pericàs, Miquel A.,Diéguez, Montserrat
supporting information, p. 4561 - 4574 (2021/04/05)
A family of phosphite/phosphinite-thioether ligands have been tested in the Ir-catalyzed asymmetric hydrogenation of a range of olefins (50 substrates in total). The presented ligands are synthesized in three steps from cheap indene and they are air-stable solids. Their modular architecture has been crucial to maximize the catalytic performance for each type of substrate. Improving most Ir-catalysts reported so far, this ligand family presents a broader substrate scope, covering different substitution patterns with different functional groups, ranging from unfunctionalized olefins, through olefins with poorly coordinative groups, to olefins with coordinative functional groups. α,β-Unsaturated acyclic and cyclic esters, ketones and amides werehydrogenated in enantioselectivities ranging from 83 to 99% ee. Enantioselectivities ranging from 91 to 98% ee were also achieved for challenging substrates such as unfunctionalized 1,1′-disubstituted olefins, functionalized tri- and 1,1′-disubstituted vinyl phosphonates, and β-cyclic enamides. The catalytic performance of the Ir-ligand assemblies was maintained when the environmentally benign 1,2-propylene carbonate was used as solvent. (Figure presented.).
Manganese-catalyzed homogeneous hydrogenation of ketones and conjugate reduction of α,β-unsaturated carboxylic acid derivatives: A chemoselective, robust, and phosphine-free in situ-protocol
Topf, Christoph,Vielhaber, Thomas
, (2021/07/10)
We communicate a user-friendly and glove-box-free catalytic protocol for the manganese-catalyzed hydrogenation of ketones and conjugated C[dbnd]C[sbnd]bonds of esters and nitriles. The respective catalyst is readily assembled in situ from the privileged [Mn(CO)5Br] precursor and cheap 2-picolylamine. The catalytic transformations were performed in the presence of t-BuOK whereby the corresponding hydrogenation products were obtained in good to excellent yields. The described system offers a brisk and atom-efficient access to both secondary alcohols and saturated esters avoiding the use of oxygen-sensitive and expensive phosphine-based ligands.
A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
supporting information, p. 16865 - 16873 (2021/10/20)
Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
Asymmetric Hydrogenation of ?-Aryl Alkylidene Malonate Esters: Installing an Ester Group Significantly Increases the Efficiency
Zhao, Qian-Kun,Wu, Xiong,Li, Lin-Ping,Yang, Fan,Xie, Jian-Hua,Zhou, Qi-Lin
supporting information, p. 1675 - 1680 (2021/03/08)
Herein, we report a practical method for efficient asymmetric hydrogenation of β-aryl alkylidene malonates. With a site-specifically tailored chiral spiro iridium catalyst, a series of β-aryl alkylidene malonate esters were hydrogenated to afford chiral m
Synthesis and Asymmetric Alkene Hydrogenation Activity of C2-Symmetric Enantioenriched Pyridine Dicarbene Iron Dialkyl Complexes
Viereck, Peter,Rummelt, Stephan M.,Soja, Natalia A.,Pabst, Tyler P.,Chirik, Paul J.
supporting information, p. 1053 - 1061 (2021/05/07)
Enantioenriched N-alkyl-imidazole-substituted pyridine dicarbene iron dialkyl complexes have been synthesized and characterized by 1H NMR and zero-field 57Fe M?ssbauer spectroscopies as well as single-crystal X-ray diffraction. In benzene-d6, reversible coordination of N2 was observed establishing an equilibrium between a five-coordinate, S = 1 iron dialkyl derivative and the corresponding six-coordinate, diamagnetic dinitrogen complex. A modest enantioselectivity of 45% enantiomeric excess (ee) was observed for the catalytic asymmetric hydrogenation of 1-isopropyl-1-phenyl ethylene at 4 atm of H2 using 10 mol % of an enantioenriched iron dialkyl precatalyst, (ACNC)Fe(CH2SiMe3)2 ((ACNC) = bis(alkylimidazol-2-ylidene)pyridine). Decreasing the H2 pressure to 1 atm increased the ee to 70%. Incubation experiments established that the reaction of the iron dialkyl precatalysts with H2 initiates a background reaction leading to the generation of a less selective catalyst; suppressing this pathway is crucial for obtaining high enantioselectivity. The attempted hydrogenation of methyl-2-acetamidoacrylate identified a deactivation pathway where N-H bond activation generated an iron alkyl κ2-amidate alkyl. For productive catalytic reactions, deuterium labeling studies are consistent with a pathway for hydrogenation involving fast, reversible [2,1]-alkene insertion and a slow, enantiodetermining [1,2]-insertion. Monitoring the catalytic alkene hydrogenation reaction by NMR spectroscopy supports a homogeneous active catalyst that also undergoes C-H activation of the ACNC ligand backbone as a competing reaction.
N-benzylpiperidinol derivatives as novel USP7 inhibitors: Structure–activity relationships and X-ray crystallographic studies
Chen, Caiping,Chen, Hui,Cheng, Keguang,Li, Minglei,Liu, Jun,Liu, Shengjie,Sun, Hongbin,Wang, Yue,Wen, Xiaoan,Xu, Qing-Long,Yuan, Haoliang,Zhou, Jin,Zhou, Shuxi,Zhou, Xinyu
, (2020/06/03)
USP7 as a deubiquitinase plays important roles in regulating the stability of some oncoproteins including MDM2 and DNMT1, and thus represents a potential anticancer target. Through comparative analysis of USP7 co-crystal structures in complex with the rep
Asymmetric Umpolung Hydrogenation and Deuteration of Alkenes Catalyzed by Nickel
Guo, Siyu,Wang, Xiuhua,Zhou, Jianrong Steve
supporting information, p. 1204 - 1207 (2020/02/04)
Nickel-catalyzed asymmetric hydrogenation of several types of alkenes proceeds in high enantioselectivity, using acetic acid or water as the hydrogen source and indium powder as electron donor. The scope of alkenes herein include α,β-unsaturated esters, n
Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands
Mimura, Shohei,Mizushima, Sho,Sawamura, Masaya,Shimizu, Yohei
supporting information, p. 537 - 543 (2020/05/14)
A chiral phenol–NHC ligand enabled the copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters. The phenol moiety of the chiral NHC ligand played a critical role in producing the enantiomerically enriched products. The catalyst worked well for various (Z)-isomer substrates. Opposite enantiomers were obtained from (Z)- and (E)-isomers, with a higher enantiomeric excess from the (Z)-isomer.
