19099-48-0Relevant articles and documents
Tunable and Practical Homogeneous Organic Reductants for Cross-Electrophile Coupling
Barth, Emily L.,Charboneau, David J.,Germe, Cameron C.,Hazari, Nilay,Huang, Haotian,Mercado, Brandon Q.,Uehling, Mycah R.,Zultanski, Susan L.
, p. 21024 - 21036 (2021/12/14)
The syntheses of four new tunable homogeneous organic reductants based on a tetraaminoethylene scaffold are reported. The new reductants have enhanced air stability compared to current homogeneous reductants for metal-mediated reductive transformations, such as cross-electrophile coupling (XEC), and are solids at room temperature. In particular, the weakest reductant is indefinitely stable in air and has a reduction potential of -0.85 V versus ferrocene, which is significantly milder than conventional reductants used in XEC. All of the new reductants can facilitate C(sp2)-C(sp3) Ni-catalyzed XEC reactions and are compatible with complex substrates that are relevant to medicinal chemistry. The reductants span a range of nearly 0.5 V in reduction potential, which allows for control over the rate of electron transfer events in XEC. Specifically, we report a new strategy for controlled alkyl radical generation in Ni-catalyzed C(sp2)-C(sp3) XEC. The key to our approach is to tune the rate of alkyl radical generation from Katritzky salts, which liberate alkyl radicals upon single electron reduction, by varying the redox potentials of the reductant and Katritzky salt utilized in catalysis. Using our method, we perform XEC reactions between benzylic Katritzky salts and aryl halides. The method tolerates a variety of functional groups, some of which are particularly challenging for most XEC transformations. Overall, we expect that our new reductants will both replace conventional homogeneous reductants in current reductive transformations due to their stability and relatively facile synthesis and lead to the development of novel synthetic methods due to their tunability.
Dual Nickel- And Photoredox-Catalyzed Reductive Cross-Coupling of Aryl Halides with Dichloromethane via a Radical Process
Xu, Tao,Xu, Wenhao,Zheng, Purui
supporting information, (2020/11/13)
The first catalytic strategy to harness a new chloromethane radical from dichloromethane under dual Ni/photoredox catalytic conditions has been developed. Compared with traditional two-electron reductive process associated with metallic reductants, this method via a single-electron approach can proceed under exceptionally mild conditions (visible light, ambient temperature, no strong base) and exhibits complementary reactivity patterns. It affords a broad scope of many functional groups, including alkenyl, which suffers cyclopropanation in previous routes. The diarylmethane-d2 compounds can be readily available with this transformation.
Mixed er-NHC/phosphine Pd(ii) complexes and their catalytic activity in the Buchwald-Hartwig reaction under solvent-free conditions
Ageshina, Alexandra A.,Sterligov, Grigorii K.,Rzhevskiy, Sergey A.,Topchiy, Maxim A.,Chesnokov, Gleb A.,Gribanov, Pavel S.,Nechaev, Mikhail S.,Asachenko, Andrey F.,Bermeshev, Maxim V.,Melnikova, Elizaveta K.
supporting information, p. 3447 - 3452 (2019/04/30)
A series of novel (NHC)PdCl2-PR3 complexes were synthesized and fully characterized by 1H, 13C, 31P NMR and FT-IR spectroscopy. These complexes showed high catalytic activity toward solvent-free Buchwald-Hartwig amination. Both primary and secondary amines were efficiently utilized under the same reaction conditions. The solvent-free synthesis of valuable N-aryl carbazoles and similar N-heterocyclic systems was described.
Thermally Stable Half-Sandwich Benzhydryl Ln(II) (Ln = Sm, Yb) Complexes Supported by Sterically Demanding Carbazolyl and Fluorenyl Ligands
Selikhov, Alexander N.,Shavyrin, Andrey S.,Cherkasov, Anton V.,Fukin, Georgy K.,Trifonov, Alexander A.
, p. 4615 - 4624 (2019/12/24)
A series of new isolable and thermally stable half-sandwich Ln(II) benzhydryl complexes coordinated by the sterically demanding ligands tert-butylcarbazol-9-yl [tBu4Carb]Ln[(p-tBu-C6H4)2CH](L) (Ln = Sm, L = DME (4); Ln = Yb, L = DME (5); Ln = Yb, L = TMEDA (6)) and 2,7-di-tert-butyl-fluoren-9-trimethylsilylyl [2,7-tBu2-9-Me3Si-C13H6]Yb[(p-tBu-C6H4)2CH](DME) (7) were synthesized by the alkane elimination reaction of [(p-tBu-C6H4)2CH]2Ln(Ln) (Ln = Sm, Yb) with tBu4CarbH and 2,7-tBu2-9-Me3Si-C13H7. X-ray analysis revealed that in 4, 5, and 7 the benzhydryl ligand is coordinated to the metal ion in an ν3 coordination mode, while in 6 it is ν1-bound. The type of coordination of the benzhydryl ligands in diamagnetic 5-7 is retained in their C6D6 solutions. Complexes 4-7 demonstrated unprecedented thermal stability and do not undergo decomposition after heating their solutions in C6D6 or toluene at 100 °C for 72 h. The reactions of [tBu4Carb]Ln[(p-tBu-C6H4)2CH](DME) (Ln = Sm (4), Ln = Yb (5)) with an excess of DME led to the formation of the symmetrical bis(carbazolyl) complex products [tBu4Carb]2Ln(DME)4 (Ln = Sm (8), Yb (9)) isolated in the form of separated ion pairs.
Thermally Stable Ln(II) and Ca(II) Bis(benzhydryl) Complexes: Excellent Precatalysts for Intermolecular Hydrophosphination of C-C Multiple Bonds
Selikhov, Alexander N.,Plankin, Gleb S.,Cherkasov, Anton V.,Shavyrin, Andrey S.,Louyriac, Elisa,Maron, Laurent,Trifonov, Alexander A.
, p. 5325 - 5334 (2019/04/17)
A series of Ln(II) and Ca(II) bis(alkyl) complexes with bulky benzhydryl ligands, [(p-tBu-C6H4)2CH]2M(Ln) (M = Sm, L = DME, n = 2 (1); M = Sm, Yb, Ca, L = TMEDA, n = 1 (2, 3, 4), were synthesized by t
Carbonyl and olefin hydrosilylation mediated by an air-stable phosphorus(iii) dication under mild conditions
Andrews, Ryan J.,Chitnis, Saurabh S.,Stephan, Douglas W.
supporting information, p. 5599 - 5602 (2019/05/21)
The readily-accessible, air-stable Lewis acid [(terpy)PPh][B(C6F5)4]21 is shown to mediate the hydrosilylation of aldehydes, ketones, and olefins. The utility and mechanism of these hydrosilylations are considered.
Facile Hydrogenolysis of C(sp3)–C(sp3) σ Bonds
Fillion, Eric,Beaton, Eric,Nguyen, Yen,Wilsily, Ashraf,Bondarenko, Ganna,Jacq, Jér?me
supporting information, p. 3422 - 3434 (2016/11/13)
The modification of benzylic quaternary, tertiary, and secondary carbon centers through palladium-catalyzed hydrogenolysis of C(sp3)–C(sp3) σ bonds is presented. When benzyl Meldrum's acid derivatives bearing quaternary benzylic centers are treated under mild hydrogenolysis conditions – palladium on carbon and atmospheric pressure of hydrogen – aromatics substituted with tertiary benzylic centers and Meldrum's acid are obtained with good to excellent yield. Analogously, substrates containing tertiary or secondary benzylic centers yield aromatics substituted with secondary benzylic centers or toluene derivatives, respectively. Furthermore, this strategy is used for the high yielding synthesis of diarylmethanes. The scope of the reductive dealkylation reaction is explored and the limitations with respect to steric and electronic factors are determined. A mechanistic analysis of the reaction is described that consisted of deuterium labelling experiments and hydrogenolysis of enantioenriched derivatives. The investigation shows that the C(sp3)–C(sp3) σ bond-cleaving events occur through a hybrid SN1/SN2 mechanism, in which the palladium center displaces a carbon-based leaving group, namely Meldrum's acid, with inversion of configuration, followed by reductive elimination of palladium to furnish a C?H bond. (Figure presented.).
Facile one-pot palladium-catalyzed sequential coupling to diarylmethanes by using aryl methyl ketones as the methylene donors
Wang, Xing,Liu, Lian-Hua,Shi, Jin-Hua,Peng, Ji,Tu, Hai-Yang,Zhang, Ai-Dong
, p. 6870 - 6877 (2013/11/06)
A novel palladium-catalyzed coupling reaction of an aryl methyl ketone with two molecules of an aryl halide to yield symmetric diarylmethanes is described. In the facile one-pot reaction, the aryl methyl ketone acts as a formal methylene donor. The experimental facts, including TLC monitoring, speculated intermediates as the raw materials, analysis of the cesium benzoate coproduct by ex situ IR spectroscopy, and the cross-coupling reactions of two different aryl halides, indicate a mechanism involving a palladium-catalyzed sequential two-step coupling process, in which the presence of a trace amount of H 2O is indispensable. The reaction is applicable to a broad spectrum of substrates and delivers the products in good to excellent yields. Access to unsymmetrical diarylmethanes with this method is also explored and various factors are discussed. An aryl methyl ketone is used as the methylene donor to couple with two molecules of an aryl halide for the synthesis of various symmetric diarylmethanes under palladium catalysis. The mechanism involves a two-step coupling process in which the presence of a trace amount of H 2O is indispensable. The cross-coupling to unsymmetrical diarylmethanes with this method is also explored. Copyright
SYNTHESIS OF SUBSTITUTED FLUORENE LIGANDS
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Page/Page column 2, (2011/02/15)
The present invention describes a cost-efficient method for preparing di-substituted fluorenes in high yield.
SYNTHESIS OF SUBSTITUTED FLUORENES
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Page/Page column 4, (2010/08/09)
The present invention describes a cost-efficient method for preparing di-substituted fluorenes in high yield.
