872-53-7Relevant articles and documents
Two-dimensional (2d) correlation analysis and the search for intermediates: A strictly mathematical approach to an important mechanistic question
Xu, Qisong,Guo, Liangfeng,Dinh, Tung Nguyen,Cheong, Angie,Garland, Marc
, p. 3588 - 3599 (2015)
In situ spectroscopic studies of metal-mediated syntheses of new and previously unstudied systems are being increasingly used to better understand speciation and mechanistic aspects. These types of experiments give rise to an interesting question: namely, can one deduce from in situ data alone, and with no a priori chemical knowledge (i.e. chemical assignments), which pure component spectral estimates correspond to intermediates? In the present contribution, a statistical 2D correlation analysis is introduced to solve this problem for unicyclic catalytic systems. Such a methodological development achieves two goals: (1) it allows the experimentalist to concentrate on the most meaningful information at the outset of a new exploratory study (focus on the species directly associated with the catalysis), and (2) it helps to free the experimentalist from chemical bias and prejudice, i.e. believing that a specific organometallic species has to be an intermediate due to one or more chemical arguments, when in fact it may be just a side product or spectator species in the metal-mediated synthesis. The 2D correlation analysis is first tested with a numerically simulated data set and then with a real in situ FTIR data set from an unmodified rhodium-catalyzed hydroformylation. The resulting statistical 2D correlation analysis provides a clear and correct answer.
Synchronicity of mononuclear and dinuclear events in homogeneous catalysis. Hydroformylation of cyclopentene using Rh4(CO)12 and HRe(CO)5 as precursors
Li, Chuanzhao,Chen, Li,Garland, Marc
, p. 13327 - 13334 (2007)
The combined application of two or more metals in homogeneous catalysis can lead to synergistic effects; however, the phenomenological basis for these observations often goes undetermined. The heterobimetallic catalytic binuclear elimination reaction, a system involving both mononuclear and dinuclear intermediates, has been repeatedly suggested as a possible mechanism. In the present contribution, the simultaneous application of Rh4(CO) 12 and HRe(CO)5 as precursors in the hydroformylation reaction leads to a very strong synergistic rate effect. In situ spectroscopic measurements confirm the presence of both mononuclear and dinuclear intermediates such as RCORh(CO)4 and RhRe(CO)9 in the active system. Moreover, kinetic analysis confirms interconversion of these intermediates as well as their statistical correlation with organic product formation. Specifically, the rate of hydrogen activation by RhRe(CO)9 is exactly equal to the rate of aldehyde formation from binuclear elimination between HRe(CO)5 and RCORh-(CO)4 at all reaction conditions studied. Thus the catalytic events involving mononuclear species and those involving dinuclear species are synchronized. In the present experiments, the new topology is orders of magnitude more efficient than the corresponding unicyclic rhodium system.
Concurrent synergism and inhibition in bimetallic catalysis: Catalytic binuclear elimination, solute-solute interactions and a hetero-bimetallic hydrogen-bonded complex in Rh-Mo hydroformylations
Li, Chuanzhao,Cheng, Shuying,Tjahjono, Martin,Schreyer, Martin,Garland, Marc
, p. 4589 - 4599 (2010)
Hydroformylations of cyclopentene and 3,3-dimethylbut-1-ene were performed using both Rh4(CO)12 and (η5-C 5H5)Mo(CO)3H as precursors in n-hexane at 298 K. Both stoichiometric and catalytic hydroformylations were conducted as well as isotopic labeling experiments. Six organometallic pure component spectra were recovered from the high-pressure FTIR experiments, namely the known species Rh4(CO)12, (η5-C5H 5)Mo(CO)3H, RCORh(CO)4, and the new heterobimetallic complexes RhMo(CO)7(η5-C 5H5), a weak hydrogen bonded species (η5- C5H5)Mo(CO)3H-C5H 9CORh(CO)4, and a substituted RhMo(CO) 7-y(η5-C5H5)Ly, where y = 1 or 2 and L = (--C5H8). The main findings were (1) catalytic binuclear elimination (CBER) occurs between (η5-C 5H5)Mo(CO)3H and RCORh(CO)4 resulting in aldehyde and RhMo(CO)7(η5-C 5H5), and this mechanism is responsible for ca. 10% of the product formation; (2) molecular hydrogen is readily activated by the new heterobimetallic complex(es); (3) FTIR and DFT spectroscopic evidence suggests that the weak hydrogen bonded species (η5-C5H 5)Mo(CO)3H-C5H9CORh(CO)4 has an interaction of the type η5-C5H4-HO - C; and (4) independent physicochemical experiments for volumes of interaction confirm that significant solute-solute interactions are present. With respect to the efficiency of the catalytic cycle, the formation of a weak (η5-C5H5)Mo(CO)3H-C 5H9CORh(CO)4 complex results in a significant decrease in the measured turnover frequency (TOF) and is the primary reason for the inhibition observed in the bimetallic catalytic hydroformylation. Such hydrogen bonding through the η5-C5H5 ring might have relevance to inhibition observed in other catalytic metallocene systems. The present catalytic system is an example of concurrent synergism and inhibition in bimetallic homogeneous catalysis.
Highly efficient polymer-based nanoreactors for selective oxidation of alcohols in water
Chen, Tao,Xu, Zhenkai,Zhou, Lei,Qiu, Jiaqi,Wang, Maolin,Wang, Jiping
, (2019/05/28)
In this study, we demonstrate the fabrication of thermo-responsive polymer-based TEMPO nanoreactors and their application in the catalytic selective oxidation of alcohols as a highly efficient and recoverable catalyst in aqueous media. First, a diblock amphiphilic copolymer NHS-P(MMA25-b-OEGMA75) consisting of poly(methyl methacrylate) (PMMA) and poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA300) with a terminal N-hydroxysuccinimide (NHS) activated ester was synthesized utilizing reversible addition–fragmentation chain transfer polymerization (RAFT) techniques. Free radical 2,2,6,6,-tetramethyipiperidinooxy (TEMPO) was then introduced into the end of the copolymer based on activated ester functionalization to afford the temperature responsive polymer-supported catalyst TEMPO-P(MMA25-b-OEGMA75). Next, core-shell TEMPO nanoreactors were formed through self-assembly of the amphiphilic block polymers in deionized water. The morphology of the nanoreactors was well characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). The nanoreactors were then successfully applied in the selective oxidative of alcohols in water. A variety of aldehydes and ketones were achieved in excellent yields and selectivities in high reaction rates with low catalyst loading. The high efficiency in catalysis of the nanoreactors may attributed to the ideal environment where enhancing the interactions between the catalyst and the alcohol substrate, mimicking the environment of enzymes. The thermo-responsive polymer-based nanoreactors could be conveniently recovered in the temperature above the LCST of the polymer after extraction of product from the reaction mixture. This strategy provides an effective and cleaner way for the selective oxidative of alcohols in organic synthesis and industrial application.
Facile One-Pot Transformation of Primary Alcohols into 3-Aryl- and 3-Alkyl-isoxazoles and -pyrazoles
Kobayashi, Eiji,Togo, Hideo
, p. 3723 - 3735 (2019/09/30)
Various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylisoxazoles in good yields in one pot by successive treatment with PhI(OAc) 2 in the presence of TEMPO, NH 2 OH, and then NCS, followed by reaction with alkynes in the presence of Et 3 N. Similarly, various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylpyrazoles in good yields in one pot by successive treatment with PhI(OAc) 2 in the presence of TEMPO, PhNHNH 2, and then NCS and decyl methyl sulfide, followed by reaction with alkynes in the presence of Et 3 N. Thus, both 3-aryl- and 3-alkylisoxazoles, and 3-aryl- and 3-alkylpyrazoles could be prepared from readily available primary alcohols in one pot under transition-metal-free conditions.
Maximizing the Number of Interfacial Sites in Single-Atom Catalysts for the Highly Selective, Solvent-Free Oxidation of Primary Alcohols
Li, Tianbo,Liu, Fei,Tang, Yan,Li, Lin,Miao, Shu,Su, Yang,Zhang, Junying,Huang, Jiahui,Sun, Hui,Haruta, Masatake,Wang, Aiqin,Qiao, Botao,Li, Jun,Zhang, Tao
supporting information, p. 7795 - 7799 (2018/06/26)
The solvent-free selective oxidation of alcohols to aldehydes with molecular oxygen is highly attractive yet challenging. Interfacial sites between a metal and an oxide support are crucial in determining the activity and selectivity of such heterogeneous catalysts. Herein, we demonstrate that the use of supported single-atom catalysts (SACs) leads to high activity and selectivity in this reaction. The significantly increased number of interfacial sites, resulting from the presence of individually dispersed metal atoms on the support, renders SACs one or two orders of magnitude more active than the corresponding nanoparticle (NP) catalysts. Lattice oxygen atoms activated at interfacial sites were found to be more selective than O2 activated on metal NPs in oxidizing the alcohol substrate. This work demonstrates for the first time that the number of interfacial sites is maximized in SACs, providing a new avenue for improving catalytic performance by developing appropriate SACs for alcohol oxidation and other reactions occurring at metal–support interfacial sites.
Ordered nanoporous lyotropic liquid crystal polymer resin for heterogeneous catalytic aerobic oxidation of alcohols
Dwulet, Gregory E.,Gin, Douglas L.
supporting information, p. 12053 - 12056 (2018/12/01)
An ordered, nanoporous, TEMPO-based polymer resin formed from lyotropic liquid crystal monomers catalyzes the hetereogeneous oxidation of alcohols with high activity and substrate size selectivity under transition-metal-free, aerobic conditions.
Green and selective oxidation of alcohols by immobilized Pd onto triazole functionalized Fe 3O 4 magnetic nanoparticles
Dadras, Arefeh,Naimi-Jamal, M Reza,Moghaddam, F Matloubi,Ayati, Seyed Ebrahim
, (2018/12/04)
Abstract: Carbonyl compounds were prepared by selective oxidation of alcohols in the presence of recoverable Fe 3O 4@ SiO 2@ Pd magnetic nanocatalyst in aqueous media as a green solvent. Molecular oxygen served as an oxidant. The catalyst was removed from the reaction media by external magnetic field, washed with methanol, and reused for six more times without any considerable reduction in its reactivity. The chemoselectivity and regioselectivity of the catalyst can serve for selective oxidation of primary alcohols in the presence of secondary ones, and for oxidation of unhindered alcohols in the presence of hindered ones. Graphical Abstract: Selective and facile oxidation of alcohols to their corresponding carbonyl compounds in the presence of immobilized, recoverable, and magnetic nano Pd-particles in water by molecular oxygen. [Figure not available: see fulltext.].
Intermediate of JAK inhibitor, and preparation method thereof
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Paragraph 0076; 0077, (2018/03/24)
The present invention relates to a novel key intermediate of a JAK inhibitor ruxolitinib, and a preparation method thereof, wherein the chemical name of the intermediate is (R)-3-(4-boric acid-1H-pyrazole-1-yl)-3-cyclopentylpropionitrile. According to the present invention, the new ruxolitinib preparation route is provided, wherein each reaction of the route has the high yield, the total yield ofthe route is high, the purity of the obtained product is good, the post-treatment of the reaction is simple, and column chromatography is not required; by adopting the route, the required raw materials or catalysts and other materials are relatively easy to obtain; and compared to the method in the prior art, the method of the present invention is economical and is suitable for industrial production.
Preparation methods of JAK inhibitor and salt thereof
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Paragraph 0063; 0064; 0075; 0076, (2018/03/24)
The present invention relates to preparation methods of a JAK inhibitor and a salt thereof. The preparation method comprises: (1) carrying out a Suzuki coupling reaction on (R)-3-(4-boronic acid-1H-pyrazol-1-yl)-3-cyclopentylpropionitrile and 6-halogen-5-(2-methoxyvinyl)pyrimidin-4-ylamine to generate (3R)-cyclopentyl-3-[4-(5-(2-methoxyvinyl)pyrimidin-4-ylamine)pyrazol-1-yl]propionitrile; and (2)carrying out a protection group removing and ring-closure reaction on the (3R)-cyclopentyl-3-[4-(5-(2-methoxyvinyl)pyrimidin-4-ylamine)pyrazol-1-yl]propionitrile to generate a JAK inhibitor ruxolitinib. According to the present invention, the new ruxolitinib preparation route is provided, wherein each reaction of the route has the high yield, the total yield of the route is high, the purity of theobtained product is good, the post-treatment of the reaction is simple, and column chromatography is not required; by adopting the route, the required raw materials or catalysts and other materials are relatively easy to obtain; and compared to the method in the prior art, the method of the present invention is economical and is suitable for industrial production.
