75867-38-8Relevant articles and documents
Preparation and Structure of Dichloropalladium(II) Complexes of Sterically Protected Diphosphinidenecyclobutanes and Their Synthetic Application as Homogeneous Catalyst.
Toyota, Kozo,Masaki, Kazuto,Abe, Tetsuya,Yoshifuji, Masaaki
, p. 221 - 222 (1995)
Sterically protected 3,4-biscyclobutenes reacted with bis(acetonitrile)-dichloropalladium(II) to give the corresponding dichloropalladium complexes and the structure of one of the complexes was confirmed by X-ray cr
Gold N-Heterocyclic Carbene Catalysts for the Hydrofluorination of Alkynes Using Hydrofluoric Acid: Reaction Scope, Mechanistic Studies and the Tracking of Elusive Intermediates
Bédard, Sandrine,Cavallo, Luigi,Falivene, Laura,Gauthier, Rapha?l,Nolan, Steven P.,Paquin, Jean-Fran?ois,Saab, Marina,Tzouras, Nikolaos V.,Van Hecke, Kristof,Zhang, Ziyun
, (2021/12/09)
An efficient and chemoselective methodology deploying gold-N-heterocyclic carbene (NHC) complexes as catalysts in the hydrofluorination of terminal alkynes using aqueous HF has been developed. Mechanistic studies shed light on an in situ generated catalyst, formed by the reaction of Br?nsted basic gold pre-catalysts with HF in water, which exhibits the highest reactivity and chemoselectivity. The catalytic system has a wide alkyl substituted-substrate scope, and stoichiometric as well as catalytic reactions with tailor-designed gold pre-catalysts enable the identification of various gold species involved along the catalytic cycle. Computational studies aid in understanding the chemoselectivity observed through examination of key mechanistic steps for phosphine- and NHC-coordinated gold species bearing the triflate counterion and the elusive key complex bearing a bifluoride counterion.
Effect of the π-bridge on the light absorption and emission in push-pull coumarins and on their supramolecular organization
Arcos-Ramos, Rafael,Carreón-Castro, María del Pilar,Farfán, Norberto,González-Rodríguez, Edgar,Guzmán-Juárez, Brenda,Maldonado-Domínguez, Mauricio,Miranda-Olvera, Montserrat,Santillan, Rosa
supporting information, (2021/11/08)
A family of eight π-extended push–pull coumarins with cross-conjugated (amide) and directly conjugated (p-phenylene, alkyne, alkene) bridges were synthesized through a convergent strategy. Using an experimentally calibrated computational protocol, their UV–Visible light absorption and emission spectra in solution were investigated. Remarkably, amide-, alkyne- and alkene-bridges undergo comparable vertical excitations. The different nature of these bridges manifests during excited-state relaxation and fluorescence. We predict that these molecules can serve as building blocks for p-type semiconductors with low reorganization energies, below 0.2 eV. Since solid-state self-assembly is crucial for this application, we examined the effect of the π-bridge over the supramolecular organization in this family of compounds to determine if stacking prevails in these π-extended coumarin derivatives. Amide and alkyne spacers allow coplanar conformations which crystallize readily; p-phenylene hinders planarity yet allows facile crystallization; alkene-bridged molecules eluded all crystallization attempts. All the crystals obtained feature dense face-to-face π-stacking with 3.5–3.7 ? interlayer distances, expected to facilitate charge transfer processes in the solid state.
Metal scavenging and catalysis by periodic mesoporous organosilicas with 2,2′-bipyridine metal chelating ligands
Waki, Minoru,Inagaki, Shinji
, (2021/06/21)
A periodic mesoporous organosilica containing 2,2′-bipyridine (BPy-PMO) was assessed as a metal scavenger and heterogeneous catalyst. The functionalized PMO was synthesized based on a modified version of a previously reported procedure and showed a large
Chemoselective Cleavage of Si-C(sp3) Bonds in Unactivated Tetraalkylsilanes Using Iodine Tris(trifluoroacetate)
Matsuoka, Keitaro,Komami, Narumi,Kojima, Masahiro,Mita, Tsuyoshi,Suzuki, Kimichi,Maeda, Satoshi,Yoshino, Tatsuhiko,Matsunaga, Shigeki
supporting information, p. 103 - 108 (2021/01/13)
Organosilanes are synthetically useful reagents and precursors in organic chemistry. However, the typical inertness of unactivated Si-C(sp3) bonds under conventional reaction conditions has hampered the application of simple tetraalkylsilanes in organic synthesis. Herein we report the chemoselective cleavage of Si-C(sp3) bonds of unactivated tetraalkylsilanes using iodine tris(trifluoroacetate). The reaction proceeds smoothly under mild conditions (-50 °C to room temperature) and tolerates various polar functional groups, thus enabling subsequent Tamao-Fleming oxidation to provide the corresponding alcohols. NMR experiments and density functional theory calculations on the reaction indicate that the transfer of alkyl groups from Si to the I(III) center and the formation of the Si-O bond proceed concertedly to afford an alkyl-λ3-iodane and silyl trifluoroacetate. The developed method enables the use of unactivated tetraalkylsilanes as highly stable synthetic precursors.
Molybdenum Benzylidyne Complexes for Olefin Metathesis Reactions
Acosta, Carlos M.,Bukhryakov, Konstantin V.,Chuprun, Sergey,Mathivathanan, Logesh
supporting information, p. 3453 - 3457 (2020/11/02)
The molybdenum benzylidynes [ArCMo(OC(CF3)2CH3)3(1,2-dimethoxyethane)], where Ar = Ph (2a), p-(OCH3)C6H4 (2b), p-(CF3)C6H4 (2c), p-(NO2)C6H4 (2d), or 4-(NO2)-3-(CF3)C6H3 (2e), and [p-(NO2)C6H4CMo(OC(CF3)2CH3)3] (2f) catalyze the ring-closing metathesis (RCM) reaction of diallyl N-tosylamide (3) to produce 1-tosyl-2,5-dihydro-1H-pyrrole (4) and ethylene. The scope of RCM catalytic activity of 2e, cross-metathesis of 1-hexene, and ring-opening metathesis polymerization of cyclooctene were explored. The X-ray crystal structure of 2e was determined. Variable-temperature 1H NMR spectra revealed the formation of intermediates during the reaction of 3 with 2f and the reforming of 2f after completion of the reaction. The use of 13C-labeled Mo benzylidyne did not show transfer of the carbon atom next to Mo to any of the products.
Catalytic Decarboxylation of Silyl Alkynoates to Alkynylsilanes
Aoyagi, Keiya,Choi, Jun-Chul,Kawatsu, Takahiro,Matsumoto, Kazuhiro,Nakajima, Yumiko,Sato, Kazuhiko
supporting information, (2020/09/15)
Herein, we describe a decarboxylative approach to the preparation of alkynylsilanes. Treatment of a silyl alkynoate in N,N-dimethylformamide (DMF) at 80 °C in the presence of catalytic amounts of CuCl and PCy3 produced the corresponding alkynylsilane in excellent yield. The copper-catalyzed decarboxylation proceeded smoothly with low catalyst loadings (0.5 mol % of CuCl and 1.0 mol % of PCy3) under mild reaction conditions and is easily scalable to gram quantities.
Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells
Yamada, Ayato,Abe, Manabu,Nishimura, Yoshinobu,Ishizaka, Shoji,Namba, Masashi,Nakashima, Taku,Shimoji, Kiyofumi,Hattori, Noboru
, p. 863 - 873 (2019/04/17)
Novel caged nitroxides (nitroxide donors) with near-infrared two-photon (TP) responsive character, 2,2,6,6-tetramethyl-1-(1-(2-(4-nitrophenyl)benzofuran-6-yl)ethoxy)piperidine (2a) and its regioisomer 2b, were designed and synthesized. The one-photon (OP) (365 ± 10 nm) and TP (710–760 nm) triggered release (i.e., uncaging) of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical under air atmosphere were discovered. The quantum yields for the release of the TEMPO radical were 2.5% (2a) and 0.8% (2b) in benzene at ≈1% conversion of 2, and 13.1% (2a) and 12.8% (2b) in DMSO at ≈1% conversion of 2. The TP uncaging efficiencies were determined to be 1.1 GM at 740 nm for 2a and 0.22 GM at 730 nm for 2b in benzene. The cytocidal effect of compound 2a on lung cancer cells under photolysis conditions was also assessed to test the efficacy as anticancer agents. In a medium containing 100 μg mL?1 of 2a exposed to light, the number of living cells decreased significantly compared to the unexposed counterparts (65.8% vs 85.5%).
Rational Design, synthesis and biological evaluation of novel triazole derivatives as potent and selective PRMT5 inhibitors with antitumor activity
Zhu, Kongkai,Shao, Jingwei,Tao, Hongrui,Yan, Xue,Luo, Cheng,Zhang, Hua,Duan, Wenhu
, p. 775 - 785 (2019/07/22)
Protein arginine methyltransferase 5 (PRMT5) is responsible for the mono-methylation and symmetric dimethylation of arginine, and its expression level and methyl transferring activity have been demonstrated to have a close relationship with tumorigenesis, development and poor clinical outcomes of human cancers. Two PRMT5 small molecule inhibitors (GSK3326595 and JNJ-64619178) have been put forward into clinical trials. Here, we describe the design, synthesis and biological evaluation of a series of novel, potent and selective PRMT5 inhibitors with antiproliferative activity against Z-138 mantle cell lymphoma cell line. Among them, compound C_4 exhibited the highest potency with enzymatic and cellular level IC50 values of 0.72 and 2.6 μM, respectively, and displayed more than 270-fold selectivity toward PRMT5 over several other isoenzymes (PRMT1, PRMT4 and PRMT6). Besides, C_4 demonstrated obvious cell apoptotic effect while reduced the cellular symmetric arginine dimethylation levels of SmD3 protein. The potency, small size, and synthetic accessibility of this compound class provide promising hit scaffold for medicinal chemists to further explore this series of PRMT5 inhibitors.
Catalytic Activation of Trimethylsilylacetylenes: A One-Pot Route to Unsymmetrical Acetylenes and Heterocycles
Lasányi, Dániel,Mészáros, ádám,Novák, Zoltán,Tolnai, Gergely L.
, p. 8281 - 8291 (2018/06/11)
For the synthesis of unsymmetrical acetylenes, a Sonogashira coupling-deprotection-Sonogashira coupling reaction sequence is often used. Removal of protecting groups requires harsh conditions or an excess of difficult to handle and expensive reagents. Herein, we disclose a novel catalytic method for the selective deprotection of trimethylsilylacetylenes in Sonogashira reaction. The reagent hexafluorosilicic acid, an inexpensive nontoxic compound, was used to promote the selective desilylation. This method enables the efficient synthesis of unsymmetric acetylenes with other silylated functional groups present. Further possibilities of the method were explored by synthesis of heterocycles.
