700-88-9Relevant academic research and scientific papers
Benzene Alkylation with Cycloolefins under the Action of [Et3NH]+[Al2Cl7]? Ionic Liquid
Aminov,Mazitova,Khusnutdinov
, p. 2171 - 2177 (2020/01/08)
Benzene alkylation with mono- and bicyclic olefins under the action of an inorganic ionic liquid [Et3NH]+[Al2Cl7]? with the formation of benzene cycloalkyl derivatives in 58–98% yield has been performed for the first time. It has been found that the increase in the olefin cycle size improves the selectivity with respect to monocycloalkyl derivatives.
Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
, p. 7596 - 7606 (2019/08/20)
Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
Amine-Borane Dehydrogenation and Transfer Hydrogenation Catalyzed by α-Diimine Cobaltates
Maier, Thomas M.,Sandl, Sebastian,Shenderovich, Ilya G.,Jacobi von Wangelin, Axel,Weigand, Jan J.,Wolf, Robert
supporting information, p. 238 - 245 (2019/01/04)
Anionic α-diimine cobalt complexes, such as [K(thf)1.5{(DippBIAN)Co(η4-cod)}] (1; Dipp=2,6-diisopropylphenyl, cod=1,5-cyclooctadiene), catalyze the dehydrogenation of several amine-boranes. Based on the excellent catalytic properties, an especially effective transfer hydrogenation protocol for challenging olefins, imines, and N-heteroarenes was developed. NH3BH3 was used as a dihydrogen surrogate, which transferred up to two equivalents of H2 per NH3BH3. Detailed spectroscopic and mechanistic studies are presented, which document the rate determination by acidic protons in the amine-borane.
Olefin-Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations
Sandl, Sebastian,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Jacobi von Wangelin, Axel
supporting information, p. 3403 - 3407 (2018/02/13)
The development of cobalt catalysts that combine easy accessibility and high selectivity constitutes a promising approach to the replacement of noble-metal catalysts in hydrogenation reactions. This report introduces a user-friendly protocol that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre-catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by TEM, EDX, and DLS supported the notion of a heterotopic catalysis mechanism.
A Manganese Nanosheet: New Cluster Topology and Catalysis
Chakraborty, Uttam,Reyes-Rodriguez, Efrain,Demeshko, Serhiy,Meyer, Franc,Jacobi von Wangelin, Axel
supporting information, p. 4970 - 4975 (2018/03/28)
While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three-dimensional structures and rapid aggregation or decomposition. A simple ligand-exchange procedure has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat-chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the manganese ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.
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.
Enantioselective Radical Cyclization for Construction of 5-Membered Ring Structures by Metalloradical C-H Alkylation
Wang, Yong,Wen, Xin,Cui, Xin,Zhang, X. Peter
, p. 4792 - 4796 (2018/04/17)
Radical cyclization represents a powerful strategy for construction of ring structures. Traditional radical cyclization, which is based on radical addition as the key step, necessitates the use of unsaturated substrates. Guided by the concept of metalloradical catalysis, a different mode of radical cyclization that can employ saturated C-H substrates is demonstrated through the development of a Co(II)-based system for catalytic activation of aliphatic diazo compounds for enantioselective radical alkylation of various C(sp3)-H bonds. It allows for efficient construction of chiral pyrrolidines and other valuable 5-membered cyclic compounds. This alternative strategy of radical cyclization provides a new retrosynthetic paradigm to prepare five-membered cyclic molecules from readily available open-chain aldehydes through the union of C-H and C=O elements for C-C bond formation.
Cross-coupling method of alkyl chloride and phenyl magnesium bromide
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Paragraph 0020; 0021; 0022, (2018/07/28)
The invention provides a cross-coupling method of an alkyl chloride and phenyl magnesium bromide, wherein a copper salt is used as a catalyst, the 2-methyltetrahydrofuran solution of phenyl magnesiumbromide is used as a coupling reagent, and the corss-coupling of the inactive secondary/tertiary alkyl chloride and the phenyl magnesium bromide is achieved. According to the present invention, the method has the high yield, does not require the addition of the ligand, is simple and easy to perform, and has important significance in the synthesis of complex molecules such as natural products, chiral drugs, and the like.
Teaching an old carbocation new tricks: Intermolecular C-H insertion reactions of vinyl cations
Popov, Stasik,Shao, Brian,Bagdasarian, Alex L.,Benton, Tyler R.,Zou, Luyi,Yang, Zhongyue,Houk,Nelson, Hosea M.
, p. 381 - 387 (2018/08/07)
Vinyl carbocations have been the subject of extensive experimental and theoretical studies over the past five decades. Despite this long history in chemistry, the utility of vinyl cations in chemical synthesis has been limited, with most reactivity studies focusing on solvolysis reactions or intramolecular processes. Here we report synthetic and mechanistic studies of vinyl cations generated through silylium-weakly coordinating anion catalysis. We find that these reactive intermediates undergo mild intermolecular carbon-carbon bond-forming reactions, including carbon-hydrogen (C-H) insertion into unactivated sp3 C-H bonds and reductive Friedel-Crafts reactions with arenes. Moreover, we conducted computational studies of these alkane C-H functionalization reactions and discovered that they proceed through nonclassical, ambimodal transition structures. This reaction manifold provides a framework for the catalytic functionalization of hydrocarbons using simple ketone derivatives.
Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
, p. 1996 - 2003 (2017/02/26)
Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
