628-92-2Relevant articles and documents
Ruthenium-Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism
Huang, Lin,Bismuto, Alessandro,Rath, Simon A.,Trapp, Nils,Morandi, Bill
supporting information, p. 7290 - 7296 (2021/03/01)
The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis. Here, we report a conceptually novel strategy for the catalytic, intermolecular dehydrogenation of alkanes using a ruthenium catalyst. The combination of a redox-active ligand and a sterically hindered aryl radical intermediate has unleashed this novel strategy. Importantly, mechanistic investigations have been performed to provide a conceptual framework for the further development of this new catalytic dehydrogenation system.
Chemical trigger-enabled bioconjugation reaction
Cao, Yu,Du, Juanjuan,Jia, Xiangqian,Jiang, Haolin,Tang, Yefeng,Wu, Yunfei,Xie, Fayang,Yang, Hongzhi,Zhou, Bing,Zhu, Rui,Zhu, Zhu
, p. 8343 - 8351 (2021/10/12)
Development of conceptually novel and practically useful bioconjugation reactions has been an intense pursuit of chemical biology research. Herein, we report an unprecedented bioconjugation reaction that hinges on a chemical trigger-enabled inverse-electron-demand Diels-Alder (IEDDA) cycloaddition oftrans-cycloheptene (TCH) with tetrazine. Unlike the conventional strain-promoted bioconjugation reactions that utilize built-in strained alkenes as reactants, the current one features a “trigger-release-conjugate” reaction model, in which a highly strained TCH species is released from a bench-stable bicyclicN-nitrosourea (BNU) derivative upon treatment with an external stimulus. It is noteworthy that the reactivity-stability balance of BNU derivatives could be tuned by manipulating their N-1 substituents. As a proof-of-concept case, this new chemical trigger-enabled IEDDA reaction has been applied toin vitroprotein labeling and pretargeted cell imaging. This work opens a new avenue to utilize BNU derivatives as a new class of chemical reporters in bioconjugate chemistry.
Cavitands as Containers for α,ω-Dienes and Chaperones for Olefin Metathesis
Wu, Nai-Wei,Petsalakis, Ioannis D.,Theodorakopoulos, Giannoula,Yu, Yang,Rebek, Julius
supporting information, p. 15091 - 15095 (2018/10/31)
Described herein is the behavior of α,ω-dienes sequestered within cavitands in aqueous (D2O) solution. Hydrophobic forces drive the dienes into the cavitands in conformations that best fill the available space. Shorter dienes (C9 and C10) bind
Iron-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions between Alkyl Halides and Unactivated Arylboronic Esters
Crockett, Michael P.,Tyrol, Chet C.,Wong, Alexander S.,Li, Bo,Byers, Jeffery A.
supporting information, p. 5233 - 5237 (2018/09/12)
An iron-catalyzed cross-coupling reaction between alkyl halides and arylboronic esters was developed that does not involve activation of the boronic ester with alkyllithium reagents nor requires magnesium additives. A combination of experimental and theoretical investigations revealed that lithium amide bases coupled with iron complexes containing deprotonated cyanobis(oxazoline) ligands were best to obtain high yields (up to 89%) in catalytic cross-coupling reactions. Mechanistic investigations implicate carbon-centered radical intermediates and highlight the critical importance of avoiding conditions that lead to iron aggregates. The new iron-catalyzed Suzuki-Miyaura reaction was applied toward the shortest reported synthesis of the pharmaceutical Cinacalcet.
Heterobimetallic Rebound: A Mechanism for Diene-to-Alkyne Isomerization with M - -Zr Hydride Complexes (M = Al, Zn, and Mg)
Butler,White,Crimmin
supporting information, p. 949 - 956 (2018/03/30)
The reaction of a series of M·Zr heterobimetallic hydride complexes with dienes and alkynes has been investigated (M = Al, Zn, and Mg). Reaction of M·Zr with 1,5-cyclooctadiene led to diene isomerization to 1,3-cyclooctadiene, but for M = Zn also result in an on-metal diene-to-alkyne isomerization. The resulting cyclooctyne fragment is trapped between Zr and Zn metals in a heterobimetallic species that does not form for M = Mg or Al. The scope of diene isomerization and alkyne trapping has been explored leading to the isolation of three new heterobimetallic slipped metallocyclopropene complexes. The mechanism of diene-to-alkyne isomerization was investigated through kinetics. While the reaction is first-order in Zn·Zr at high diene concentration and proceeds with ΔH? = +33.6 ± 0.7 kcal mol-1, ΔS? = +23.2 ± 1.7 cal mol-1 K-1, and ΔG?298 K = +26.7 ± 1.2 kcal mol-1, the rate is dependent on the nature of the diene. The positive activation entropy is suggestive of involvement of a dissociative step. On the basis of DFT calculations, a heterobimetallic rebound mechanism for diene-to-alkyne isomerization has been proposed. This mechanism explains the origin of heterobimetallic control over selectivity: Mg - -Zr complexes are too strongly bound to generate reactive fragments, while Al - -Zr complexes are too weakly bound to compensate for the contrathermodynamic isomerization process. Zn - -Zr complexes have favorable energetics for both dissociation and trapping steps.
Bisphosphine compd., and Bisphosphine compound and a transition metal catalyst, and method of manufacturing the same (by machine translation)
-
Paragraph 0554; 0560; 0561, (2016/11/17)
PROBLEM TO BE SOLVED: To provide a bisphosphine compound with a new bidentate phosphine ligand having a highly bulky substituent group on a phosphorus atom, which enables highly efficient and highly selective progress in various organic synthesis reactions, especially, cross coupling reaction, and a transition metal catalyst using the bisphosphine compound as a ligand, and a method for manufacturing them.SOLUTION: There are provided a bisphosphine compound represented by general formula (A) or general formula (B) and a transition metal catalyst using the bisphosphine compound as a ligand, and a method for manufacturing them.
Method of preparing cycloheptaene
-
Paragraph 0045; 0046, (2017/03/14)
The present invention provides a process for preparing cycloheptene and derivatives thereof by ring-closure metathesis of asymmetric 1,8-dienes whose C-C double bond in position 8 is not terminal. Cycloheptene and also its derivatives cycloheptanone, cycloheptylamine, cycloheptane-carbaldehyde, cycloheptanecarboxylic acid and cycloheptanecarbonyl chloride, and also their derivatives, are important synthetic building blocks for active compounds. The ring-closure metathesis is performed preferably as a reactive distillation. The asymmetric 1,8-dienes for the ring-closure metathesis can be obtained by catalytic decarbonylation or oxidative decarboxylation of the corresponding unsaturated carboxylic acids and/or carboxylic acid derivatives.
Convergent Synthesis of a Metal-Organic Framework Supported Olefin Metathesis Catalyst
Yuan, Jian,Fracaroli, Alejandro M.,Klemperer, Walter G.
, p. 2149 - 2155 (2016/07/07)
Synthesis of a metal-organic framework (MOF)-supported olefin metathesis catalyst has been accomplished for the first time following a new, convergent approach where an aldehyde-functionalized derivative of Hoveyda's recently reported ruthenium catecholate olefin metathesis catalyst is condensed with an amine-functionalized IRMOF-74-III. The resulting material, denoted MOF-Ru, has well-defined, catalytically active ruthenium centers confined within channels having a ca. 20 ? diameter. MOF-Ru is a recyclable, single-site catalyst for self-cross-metathesis and ring-closing metathesis of terminal olefins. Comparison of this heterogeneous catalyst with a homogeneous analogue shows different responses to substrate size and shape suggestive of confinement effects. The MOF-Ru catalyst also displays greater resistance to double-bond migration that can be attributed to greater catalyst stability. For the preparation of well-defined, single-site heterogeneous catalysts where catalyst purity is essential, the convergent approach employed here, where the catalytic center is prepared ex situ and covalently linked to an intact MOF, offers an attractive alternative to in situ catalyst preparation as currently practiced in MOF chemistry.
Highly nucleophilic dipropanolamine chelated boron reagents for aryl-transmetallation to iron complexes
Dunsford, Jay J.,Clark, Ewan R.,Ingleson, Michael J.
supporting information, p. 20577 - 20583 (2015/12/04)
New aryl- and heteroarylboronate esters chelated by dipropanolamine are synthesised directly from boronic acids. The corresponding anionic borates are readily accessible by deprotonation and demonstrate an increase in hydrocarbyl nucleophilicity in comparison to other common borates. The new borates proved competent for magnesium or zinc additive-free, direct boron-to-iron hydrocarbyl transmetallations with well-defined iron(ii) (pre)catalysts. The application of the new borate reagents in representative Csp2-Csp3 cross-coupling led to almost exclusive homocoupling unless coupling is performed in the presence of a zinc additive.
Carbon-carbon bond formation reactivity of a four-coordinate NHC-supported iron(II) phenyl compound
Liu, Yuesheng,Xiao, Jie,Wang, Lei,Song, You,Deng, Liang
, p. 599 - 605 (2015/03/05)
The preparation and characterization of a NHC-coordinated (NHC = N-heterocyclic carbene) ferrous phenyl complex [(IPr2Me2)2FePh2] (1; IPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) as well as its C-C bond formation reactivity have been studied. The four-coordinate iron(II) phenyl complex was prepared from the reaction of ferrous chloride with PhMgBr and IPr2Me2. It reacts with nonactivated primary and secondary alkyl bromides and chlorides to furnish cross-coupling products and the iron(II) monophenyl species (IPr2Me2)2FePhX (X = Br (2), Cl). When it is treated with cyclooctatetraene (cot) or [Cp2Fe][BArF4] in the presence of PMe3, it undergoes coordination or one-electron oxidation induced reductive elimination of biphenyl to form the corresponding iron(0) or iron(I) species [(IPr2Me2)2Fe(?·4-cot)] (3) or [(IPr2Me2)2Fe(PMe3)2][BArF4] (4). All of these iron-containing products have been fully characterized by various spectroscopic methods. Complex 1 and (IPr2Me2)2FeCl2 catalyze the reaction of n-C8H17Br with (p-tolyl)MgBr to afford the cross-coupling product in moderate yields (49% and 47%), whereas the reactions employing 4 and 1/PMe3 as catalysts give the cross-coupling product in very low yields. The results reflect the complexity of the reaction mechanism of iron-catalyzed coupling reactions.
