181219-01-2Relevant articles and documents
Enzyme-like Supramolecular Iridium Catalysis Enabling C?H Bond Borylation of Pyridines with meta-Selectivity
Al-Shehimy, Shaymaa,Gramage-Doria, Rafael,Roisnel, Thierry,Trouvé, Jonathan,Zardi, Paolo
supporting information, p. 18006 - 18013 (2021/05/07)
The use of secondary interactions between substrates and catalysts is a promising strategy to discover selective transition metal catalysts for atom-economy C?H bond functionalization. The most powerful catalysts are found via trial-and-error screening due to the low association constants between the substrate and the catalyst in which small stereo-electronic modifications within them can lead to very different reactivities. To circumvent these limitations and to increase the level of reactivity prediction in these important reactions, we report herein a supramolecular catalyst harnessing Zn???N interactions that binds to pyridine-like substrates as tight as it can be found in some enzymes. The distance and spatial geometry between the active site and the substrate binding site is ideal to target unprecedented meta-selective iridium-catalyzed C?H bond borylations with enzymatic Michaelis–Menten kinetics, besides unique substrate selectivity and dormant reactivity patterns.
Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
supporting information, p. 15396 - 15405 (2021/10/12)
In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
A heterofunctional ligand approach for the preparation of high connectivity coordination polymers: Combining a "bridge" and "pillar" in one ligand
Al-Fayaad, Hydar A.,Athukorala Arachchige, Kasun S.,Clegg, Jack K.
, p. 5310 - 5315 (2020/09/03)
Two of the most successful strategies for the preparation of three-dimensional coordination polymers and MOFs are reticular synthesis and pillaring. Here we present a new approach which combines aspects of both of these by employing a heterofunctional dicarboxylic and dipyridyl ligand, 2,5-di(pyridin-4-yl)terephthalic acid (H2L). The reaction of H2L with zinc(ii) produces a non-interpenetrated 3D coordination polymer [ZnL(H2O)]n. This journal is
Cationic magnesium hydride [MgH]+ stabilized by an NNNN-type macrocycle
Lemmerz, Lara E.,Mukherjee, Debabrata,Spaniol, Thomas P.,Wong, Anthony,Ménard, Gabriel,Maron, Laurent,Okuda, Jun
supporting information, p. 3199 - 3202 (2019/05/08)
A magnesium hydride cation [(L)MgH]+ supported by a macrocyclic ligand (L = Me4TACD; 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane) has been prepared by partial protonolysis of a mixed amide hydride [(L)MgH2Mg{N(SiMe3)2}2] and shown to undergo a variety of reactions with unsaturated substrates, including pyridine.
para-Selective C?H Borylation of (Hetero)Arenes by Cooperative Iridium/Aluminum Catalysis
Yang, Lichen,Semba, Kazuhiko,Nakao, Yoshiaki
supporting information, p. 4853 - 4857 (2017/04/11)
para-Selective C?H borylation of benzamides and pyridines has been achieved by cooperative iridium/aluminum catalysis. A combination of iridium catalysts commonly employed for arene C?H borylation and bulky aluminum-based Lewis acid catalysts provides an unprecedented strategy for controlling the regioselectivity of C?H borylation to give variously substituted (hetero)arylboronates, which are versatile synthetic intermediates for complex multi-substituted aromatic compounds.
Mitigation of Acetylcholine Esterase Activity in the 1,7-Diazacarbazole Series of Inhibitors of Checkpoint Kinase 1
Gazzard, Lewis,Williams, Karen,Chen, Huifen,Axford, Lorraine,Blackwood, Elizabeth,Burton, Brenda,Chapman, Kerry,Crackett, Peter,Drobnick, Joy,Ellwood, Charles,Epler, Jennifer,Flagella, Michael,Gancia, Emanuela,Gill, Matthew,Goodacre, Simon,Halladay, Jason,Hewitt, Joanne,Hunt, Hazel,Kintz, Samuel,Lyssikatos, Joseph,Macleod, Calum,Major, Sarah,Médard, Guillaume,Narukulla, Raman,Ramiscal, Judi,Schmidt, Stephen,Seward, Eileen,Wiesmann, Christian,Wu, Ping,Yee, Sharon,Yen, Ivana,Malek, Shiva
, p. 5053 - 5074 (2015/07/02)
Checkpoint kinase 1 (ChK1) plays a key role in the DNA damage response, facilitating cell-cycle arrest to provide sufficient time for lesion repair. This leads to the hypothesis that inhibition of ChK1 might enhance the effectiveness of DNA-damaging therapies in the treatment of cancer. Lead compound 1 (GNE-783), the prototype of the 1,7-diazacarbazole class of ChK1 inhibitors, was found to be a highly potent inhibitor of acetylcholine esterase (AChE) and unsuitable for development. A campaign of analogue synthesis established SAR delineating ChK1 and AChE activities and allowing identification of new leads with improved profiles. In silico docking using a model of AChE permitted rationalization of the observed SAR. Compounds 19 (GNE-900) and 30 (GNE-145) were identified as selective, orally bioavailable ChK1 inhibitors offering excellent in vitro potency with significantly reduced AChE activity. In combination with gemcitabine, these compounds demonstrate an in vivo pharmacodynamic effect and are efficacious in a mouse p53 mutant xenograft model.
Iridium-catalyzed C-H borylation of heteroarenes: Scope, regioselectivity, application to late-stage functionalization, and mechanism
Larsen, Matthew A.,Hartwig, John F.
supporting information, p. 4287 - 4299 (2014/04/03)
A study on the iridium-catalyzed C-H borylation of heteroarenes is reported. Several heteroarenes containing multiple heteroatoms were found to be amenable to C-H borylation catalyzed by the combination of an iridium(I) precursor and tetramethylphenanthroline. The investigations of the scope of the reaction led to the development of powerful rules for predicting the regioselectivity of borylation, foremost of which is that borylation occurs distal to nitrogen atoms. One-pot functionalizations are reported of the heteroaryl boronate esters formed in situ, demonstrating the usefulness of the reported methodology for the synthesis of complex heteroaryl structures. Application of this methodology to the synthesis and late-stage functionalization of biologically active compounds is also demonstrated. Mechanistic studies show that basic heteroarenes can bind to the catalyst and alter the resting state from the olefin-bound complex observed during arene borylation to a species containing a bound heteroarene, leading to catalyst deactivation. Studies on the origins of the observed regioselectivity show that borylation occurs distal to N-H bonds due to rapid N-H borylation, creating an unfavorable steric environment for borylation adjacent to these bonds. Computational studies and mechanistic studies show that the lack of observable borylation of C-H bonds adjacent to basic nitrogen is not the result of coordination to a bulky Lewis acid prior to C-H activation, but the combination of a higher-energy pathway for the borylation of these bonds relative to other C-H bonds and the instability of the products formed from borylation adjacent to basic nitrogen.
Synthesis and luminescent properties of color-tunable lanthanide complexes with 5-(pyridin-4-yl)isophthalic acid
Song, Tao,Rao, Xingtang,Cui, Yuanjing,Yang, Yu,Qian, Guodong
, p. 22 - 27 (2013/05/08)
In this work, a T-shape organic molecule 5-(pyridin-4-yl)isophthalic acid was synthesized via a Suzuki coupling reaction and used as the ligand for a serial of mixed-lanthanide complexes. The chemical compositions of the lanthanide complexes were determined as (EuxTb1-x) 2L3(H2O)4 by elemental analysis (EA) and thermo gravimetric analysis (TGA). The luminescent properties of the as-synthesized complexes were investigated and the intramolecular energy transfer mechanisms involved, were discussed. Efficient energy transfer from Tb3+ to Eu3+ was observed and controlled by changing the molar ratio of Tb3+ to Eu3+ ions, allowing the color tuning on the luminescent emission of the mixed-lanthanide complexes.
Hydrolytic stability of nitrogenous-heteroaryltrifluoroborates under aqueous conditions at near neutral pH
Li, Ying,Asadi, Ali,Perrin, David M.
experimental part, p. 377 - 382 (2009/12/04)
The hydrolytic stability of heteroaryltrifluoroborates under physiological conditions has been analyzed by 19F NMR spectroscopy and is found to be greatly enhanced by the presence of endocyclic ring nitrogens. Stability is further enhanced by the presence of exocyclic electron withdrawing substituents. As with aryltrifluoroborates, NMR analysis suggests that the hydrolysis proceeds via single rate-determining step reflecting loss of the first fluoride atom. The stability of these complexes is significant both in terms of metal catalyzed cross-coupling reactions as well as the potential for generating boronic acid based 18F-PET imaging agents.
Synthesis of 4-[N-methyl-4-pyridinio]-phenolate (POMP) and negative solvatochromism of this model molecule in view of nonlinear optical applications
Diemer, Vincent,Chaumeil, Hélène,Defoin, Albert,Jacques, Patrice,Carré, Christiane
, p. 4737 - 4740 (2007/10/03)
4-[N-Methyl-4-pyridinio]-phenolate or [4-(phenyloxido)-N-methylpyridinium, POMP] has been synthesized via Suzuki cross-coupling reaction. POMP undergoes a strong negative solvatochromism (blue shift) as the solvent polarity increases and behaves qualitati
