1120-87-2Relevant articles and documents
Unusual carbonyl...carbonyl interaction in supramolecular structures of silver(I) complexes with 2,6-pyridinediylbis(4-pyridinyl)methanone
Wan, Chong-Qing,Mak, Thomas C. W.
, p. 832 - 842 (2011)
A series of silver(I) complexes of a higher homologue of di-2-pyridyl ketone, 2,6-pyridinediylbis(4-pyridinyl)methanone (abbreviated as L), consisting of {[Ag(L)(BF4)]·H2O}∞ (1), {[Ag(L)(NO3)]·H2O}∞ (2), [Ag 3(L)2(NO2)3(H2O)] ∞ (3), [Ag(L)]2(PF6)2 (4), {[Ag(L)(CO2CF3)]2}∞ (5), [Ag(L)]2(SO3CF3)2 (6), and [Ag(L)]2(CO2CF2CF3)2 (7), have been synthesized and characterized. Complexes 1 and 2 are isomorphous helical polymers, 3 is a metallacycle featuring a trisilver(I) core, and 4-7 are isostructural complexes containing a common dinuclear [Ag2(L) 2]2+ metallacyclic skeleton. All complexes except 4 feature a common dominant intermolecular multipolar carbonyl...carbonyl interaction, which along with argentophilic Ag(I)...Ag(I), π...π, hydrogen-bonding, Ag...O=C, O(trifluoroacetate)...C= O as well as unconventional C=O...π and anion-π(pyridyl) interactions assemble the different coordination motifs (1-3, 5-7) into higher-dimensional frameworks. Three principal types of carbonyl...carbonyl interaction exhibiting antiparallel, sheared parallel, and perpendicular motifs are observed, and unusual supramolecular associations such as "...[C= O...C=O]n ..." (in 1-2 and 6) and "...[C= O...C=O...π]n..." (in 3) and "C=O...C=O...C=O" (in 7) are the novel structural features established in these complexes. The geometrical parameters and role of such noncovalent interactions in the construction of the present series of supramolecular metal-organic frameworks are discussed.
Enhancing a Molecular Electrocatalyst's Activity for CO2Reduction by Simultaneously Modulating Three Substituent Effects
Nie, Weixuan,Tarnopol, Drew E.,McCrory, Charles C. L.
, p. 3764 - 3778 (2021)
The electrocatalytic activity for CO2 reduction is greatly enhanced for Co complexes with pyridyldiimine-based ligands through the stepwise integration of three synergistic substituent effects: extended conjugation, electron-withdrawing ability, and intramolecular electrostatic effects. The stepwise incorporation of these effects into the catalyst structures results in a series of complexes that show an atypical inverse scaling relationship for CO2 reduction - the maximum activity of the resulting catalysts increases as the onset potentials are driven positive due to the ligand electronic substituent effects. Incorporating all three effects simultaneously into the catalyst structure results in a Co complex [Co(PDI-PyCH3+I-)] with dramatically enhanced activity for CO2 reduction, operating with over an order of magnitude higher activity (TOFcat = 4.1 × 104 s-1) and ～0.2 V more positive catalytic onset (Eonset = -1.52 V vs Fc+/0) compared to the parent complex, an intrinsic activity parameter TOF0 = 6.3 × 10-3 s-1, and >95% Faradaic efficiency for CO production in acetonitrile with 11 M water. This makes [Co(PDI-PyCH3+I-)] among the most active molecular catalysts reported for the CO2 reduction reaction. Our work highlights a promising catalyst design strategy for molecular CO2RR catalysts in which catalytic ability is enhanced by tuning three synergistic substituent effects simultaneously in a single catalyst structure.
Electrophotochemical Ring-Opening Bromination oftert-Cycloalkanols
Yamamoto, Kosuke,Toguchi, Hiroyuki,Kuriyama, Masami,Watanabe, Shin,Iwasaki, Fumiaki,Onomura, Osamu
, p. 16177 - 16186 (2021/09/13)
An electrophotochemical ring-opening bromination of unstrainedtert-cycloalkanols has been developed. This electrophotochemical method enables the oxidative transformation of cycloalkanols with 5- to 7-membered rings into synthetically useful ω-bromoketones without the use of chemical oxidants or transition-metal catalysts. Alkoxy radical species would be key intermediates in the present transformation, which generate through homolysis of the O-Br bond in hypobromite intermediates under visible light irradiation.
Base-catalyzed aryl halide isomerization enables the 4-selective substitution of 3-bromopyridines
Bandar, Jeffrey S.,Puleo, Thomas R.
, p. 10517 - 10522 (2020/10/18)
The base-catalyzed isomerization of simple aryl halides is presented and utilized to achieve the 4-selective etherification, hydroxylation and amination of 3-bromopyridines. Mechanistic studies support isomerization of 3-bromopyridines to 4-bromopyridines proceedsviapyridyne intermediates and that 4-substitution selectivity is driven by a facile aromatic substitution reaction. Useful features of a tandem aryl halide isomerization/selective interception approach to aromatic functionalization are demonstrated. Example benefits include the use of readily available and stable 3-bromopyridines in place of less available and stable 4-halogenated congeners and the ability to converge mixtures of 3- and 5-bromopyridines to a single 4-substituted product.
Structure-activity relationship studies for the development of inhibitors of murine adipose triglyceride lipase (ATGL)
Breinbauer, Rolf,Doler, Carina,Fuchs, Elisabeth,Grabner, Gernot F.,Mayer, Nicole,Melcher, Michaela-Christina,Migglautsch, Anna K.,Romauch, Matthias,Schweiger, Martina,Zechner, Rudolf,Zimmermann, Robert
supporting information, (2020/07/13)
High serum fatty acid (FA) levels are causally linked to the development of insulin resistance, which eventually progresses to type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) generalized in the term metabolic syndrome. Adipose triglyceride lipase (ATGL) is the initial enzyme in the hydrolysis of intracellular triacylglycerol (TG) stores, liberating fatty acids that are released from adipocytes into the circulation. Hence, ATGL-specific inhibitors have the potential to lower circulating FA concentrations, and counteract the development of insulin resistance and NAFLD. In this article, we report about structure–activity relationship (SAR) studies of small molecule inhibitors of murine ATGL which led to the development of Atglistatin. Atglistatin is a specific inhibitor of murine ATGL, which has proven useful for the validation of ATGL as a potential drug target.
One-pot homo- and cross-coupling of diazanaphthalenes via C-H substitution: Synthesis of Bis- and Tris-diazanaphthalenes
Ucar, Sefa,Dastan, Arif
supporting information, p. 4013 - 4022 (2020/09/21)
The transition metal-free coupling reactions of unactivated diazanaphthalenes were studied using only lithium tetramethylpiperidine (LiTMP) reagent. Symmetrical and nonsymmetrical bis-diazanaphthalenes were synthesized in moderate to high yield by homo- and cross-coupling of related monomers. In addition, the single-step synthesis of diquinoxalino [2,3-a: 2', 3'c] phenazine and 2,2': 3', 2″ - terquinoxaline using the appropriate equivalent amount of LiTMP was performed. The products were characterized by means of NMR spectroscopy and HRMS spectrometry.
Size-Selective Hydroformylation by a Rhodium Catalyst Confined in a Supramolecular Cage
Nurttila, Sandra S.,Brenner, Wolfgang,Mosquera, Jesús,van Vliet, Kaj M.,Nitschke, Jonathan R.,Reek, Joost N. H.
supporting information, p. 609 - 620 (2019/01/04)
Size-selective hydroformylation of terminal alkenes was attained upon embedding a rhodium bisphosphine complex in a supramolecular metal–organic cage that was formed by subcomponent self-assembly. The catalyst was bound in the cage by a ligand-template approach, in which pyridyl–zinc(II) porphyrin interactions led to high association constants (>105 m?1) for the binding of the ligands and the corresponding rhodium complex. DFT calculations confirm that the second coordination sphere forces the encapsulated active species to adopt the ee coordination geometry (i.e., both phosphine ligands in equatorial positions), in line with in situ high-pressure IR studies of the host–guest complex. The window aperture of the cage decreases slightly upon binding the catalyst. As a result, the diffusion of larger substrates into the cage is slower compared to that of smaller substrates. Consequently, the encapsulated rhodium catalyst displays substrate selectivity, converting smaller substrates faster to the corresponding aldehydes. This selectivity bears a resemblance to an effect observed in nature, where enzymes are able to discriminate between substrates based on shape and size by embedding the active site deep inside the hydrophobic pocket of a bulky protein structure.
One-Pot, Metal-Free Conversion of Anilines to Aryl Bromides and Iodides
Leas, Derek A.,Dong, Yuxiang,Vennerstrom, Jonathan L.,Stack, Douglas E.
supporting information, p. 2518 - 2521 (2017/05/24)
A metal-free synthesis of aryl bromides and iodides from anilines via halogen abstraction from bromotrichloromethane and diiodomethane is described. This one-pot reaction affords aryl halides from the corresponding anilines in moderate to excellent yields without isolation of diazonium salts. The transformation has short reaction times, a simple workup, and insensitivity to moisture and air and avoids excess halogenation. DFT calculations support a SRN1 mechanism. This method represents a convenient alternative to the classic Sandmeyer reaction.
Palladium-Catalysed Cross-Coupling Reactions Controlled by Noncovalent Zn???N Interactions
Kadri, Mohamed,Hou, Jingran,Dorcet, Vincent,Roisnel, Thierry,Bechki, Lazhar,Miloudi, Abdellah,Bruneau, Christian,Gramage-Doria, Rafael
supporting information, p. 5033 - 5043 (2017/04/18)
Non-covalent interactions between halopyridine substrates and catalytically inert building blocks, namely zinc(II)–porphyrins and zinc(II)–salphens, influence the catalytic outcome of Suzuki–Miyaura and Mizoroki–Heck palladium-catalysed cross-coupling reactions. The weak Zn???N interactions between halopyridine substrates and zinc(II)-containing porphyrins and salphens, respectively, were studied by a combination of 1H NMR spectroscopy, UV/Vis studies, Job-Plot analysis and, in some cases, X-ray diffraction studies. Additionally, the former studies revealed unique supramolecular polymeric and dimeric rearrangements in the solid state featuring weak Br???N (halogen bonding), C?H???π, Br???π and π???π interactions. The reactivity of halopyridine substrates in homogeneous palladium-catalysed cross-coupling reactions was found to correlate with the binding strength between the zinc(II)-containing scaffolds and the corresponding halopyridine. Such observation is explained by the unfavourable formation of inactive over-coordinated halopyridine???palladium species. The presented approach is particularly appealing for those cases in which substrates and/or products deactivate (or partially poison) a transition-metal catalyst.
Substituted Carbazoles-A New Class of Anthelmintic Agent
Rennison, David,Gueret, Stephanie M.,Laita, Olivia,Bland, Ross J.,Sutherland, Ian A.,Boddy, Ian K.,Brimble, Margaret A.
, p. 1268 - 1276 (2016/11/25)
A series of novel carbazoles were synthesized based on structural modifications to lead carbazole 1 (EC100≤2.5M against Haemonchus contortus in vitro), which was revealed in a small molecule screening program as a potentially promising platform for the development of new anthelmintic drugs. Subsequently, analogues 19, 21, 41, 42 (EC100≤ 1.25M, all), and 39 (EC100≤0.625M) were demonstrated to exhibit enhanced in vitro anthelmintic activity over the lead structure, with compound 39 also being shown to be active in vivo against Heligmosomoides polygyrus.
