4837-01-8Relevant articles and documents
Slow 3MLCT Formation Prior to Isomerization in Ruthenium Carbene Sulfoxide Complexes
Breen, Douglas J.,Rack, Jeffrey J.,Schrage, Briana R.,Thapa Magar, Rajani,Ziegler, Christopher J.
supporting information, p. 16120 - 16127 (2021/11/13)
A series of photochromic complexes with general formulas of [Ru(bpy)2(NHC-SR)]2+ and [Ru(bpy)2(NHC-S(O)R)]2+ were prepared and investigated by X-ray crystallography, electrochemistry, and ultrafast transient absorption spectroscopy {where bpy is 2,2′-bipyridine and NHC-SR and NHC-S(O)R are chelating thioether (-SR) and chelating sulfoxide [-S(O)R] N-heterocyclic carbene (NHC) ligands}. The only differences between these complexes are the nature of the R group on the sulfur (Me vs Ph), the identity of the carbene (imidazole vs benzimidazole), and the number of linker atoms in the chelate (CH2 vs C2H4). A total of 13 structures are presented {four [Ru(bpy)2(NHC-SR)]2+ complexes, four [Ru(bpy)2(NHC-S(O)R)]2+ complexes, and five uncomplexed ligands}, and these reveal the expected coordination geometry as predicted from other spectroscopy data. The data do not provide insight into the photochemical reactivity of these compounds. These carbene ligands do impart stability with respect to ground state and excited state ligand substitution reactions. Bulk photolysis reveals that these complexes undergo efficient S → O isomerization, with quantum yields ranging from 0.24 to 0.87. The excited state reaction occurs with a time constant ranging from 570 ps to 1.9 ns. Electrochemical studies reveal an electron transfer-triggered isomerization, and voltammograms are consistent with an ECEC (electrochemical-chemical electrochemical-chemical) reaction mechanism. The carbene facilitates an unusually slow S → O isomerization and an unusally fast O → S isomerization. Temperature studies reveal a small and negative entropy of activation for the O → S isomerization, suggesting an associative transition state in which the sulfoxide simply slides along the S-O bond during isomerization. Ultrafast studies provide evidence of an active role of the carbene in the excited state dynamics of these complexes.
Metal-free visible-light-promoted C(sp3)-H functionalization of aliphatic cyclic ethers using trace O2
Blackburn, Bryan G.,Cooke, Maria Victoria,Laulhé, Sébastien,Niu, Ben,Sachidanandan, Krishnakumar
supporting information, p. 9454 - 9459 (2021/12/09)
Presented is a light-promoted C-C bond forming reaction yielding sulfone and phosphate derivatives at room temperature in the absence of metals or photoredox catalyst. This transformation proceeds in neat conditions through an auto-oxidation mechanism which is maintained through the leaching of trace amounts of O2 as sole green oxidant. This journal is
Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow
Minozzi, Clémentine,Grenier-Petel, Jean-Christophe,Parisien-Collette, Shawn,Collins, Shawn K.
supporting information, p. 2730 - 2736 (2018/11/21)
A copper-based photocatalyst, Cu(tmp)(BINAP)BF4, was found to be active in a photoredox Appel-type conversion of alcohols to bromides. The catalyst was identified from a screening of 50 complexes and promoted the transformation of primary and secondary alcohols to their corresponding bromides and carboxylic acids to their anhydrides. The protocol was also amendable and optimized under continuous flow conditions.
Difluoro- and trifluoro diazoalkanes-complementary approaches in batch and flow and their application in cycloaddition reactions
Hock, Katharina J.,Mertens, Lucas,Metze, Friederike K.,Schmittmann, Clemens,Koenigs, Rene M.
supporting information, p. 905 - 909 (2017/08/14)
Herein we report on applications of fluorinated diazoalkanes in cycloaddition reactions, with the emphasis on studying subtle differences between diverse fluorinated diazo compounds. These differences led to two major synthetic protocols in batch and flow that allow the safe and scalable synthesis of fluoroalkyl-, sulfone-substituted pyrazolines.
Design, synthesis, and activity evaluation of selective inhibitors of anti-apoptotic Bcl-2 proteins: The effects on the selectivity of the P1 pockets in the active sites
Wang, Mingping,Tian, Wei,Wang, Chongqing,Lu, Shihai,Yang, Chao,Wang, Juan,Song, Yunlong,Zhou, Youjun,Zhu, Ju,Li, Zhiyu,Zheng, Canhui
, p. 5207 - 5211 (2016/11/09)
The anti-apoptotic Bcl-2 proteins are attractive targets for anti-cancer drug development, and the discovery of their selective inhibitors has become a research focus. In this Letter, obvious differences in the P1 pocket of the active site between Bcl-2, Bcl-xL, and Mcl-1 proteins were proposed by the structural comparison of these proteins. As a result, the groups in their inhibitors binding to the P1 pockets may have significant effect on the selectivity for these proteins. Based on this hypothesis, five types of derivatives of the lead compound B-1 were designed, and several highly selective inhibitors of Bcl-xL(E-1) or Mcl-1 proteins (G) were found. The selective inhibitors of Mcl-1 protein found in this Letter provide new structural types for the development of novel antitumor agents.
Air-Stable NNS (ENENES) Ligands and Their Well-Defined Ruthenium and Iridium Complexes for Molecular Catalysis
Dub, Pavel A.,Scott, Brian L.,Gordon, John C.
supporting information, p. 4464 - 4479 (2015/10/06)
We introduce ENENES, a new family of air-stable and low-cost NNS ligands bearing NH functionalities of the general formula E(CH2)mNH(CH2)nSR, where E is selected from -NC4H8O, -NC4H8, or -N(CH3)2, m and n = 2 and/or 3, and R = Ph, Bn, Me, or SR (part of a thiophenyl fragment). The preparation and characterization of more than 15 examples of well-defined Ru and Ir complexes supported by these ligands that are relevant to bifunctional metal-ligand M/NH molecular catalysis are reported. Reactions of NNS ligands with suitable Ru or Ir precursors afford rich and diverse solid-state and solution chemistries, producing monometallic molecules as well as bimetallics in which the ligand coordinates to the metal via either bidentate (κ2[N,N'] or κ2[N',S]) or tridentate (κ3[N,N',S]) binding modes, depending on the basicity of the sulfur atom, CH2 chain length (m or n parameter), or identity of the transition metal. In the case of Ir, ligands bearing benzyl substituents lead to unprecedented κ4[N,N',S,C]-tetradentate core-structure complexes of the type [IrIIIHCl{κ4(N,N',S,C)-ligand}], resulting from ortho-metalation via C-H oxidative addition. Fourteen of these Ru and Ir complexes have been crystallographically characterized. Air- and moisture-stable complexes of the type trans-[RuIICl2{κ3[N,N',S]-ligand}(L)] (L = PPh3, PCy3, DMSO), and others, effect the selective hydrogenation of methyl trifluoroacetate into the important synthon trifluoroacetaldehyde methyl hemiacetal in basic methanol under relatively mild conditions (35-40 °C, 25 bar H2) with reasonable turnover numbers (i.e., > 1000), whereas the air-stable Ir monohydride complexes [IrIIIHCl{κ4(N,N',S,C)-ligand}] exhibit excellent catalytic activities and high chemoselectivity for the same reaction, reaching turnover numbers of >10 000.
POLYDENTATE LIGANDS AND THEIR COMPLEXES FOR MOLECULAR CATALYSIS
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Page/Page column 62, (2016/01/01)
The present invention relates generally to novel achiral and chiral sulfur-, nitrogen- and phosphorus-containing ligands, designated as NNS-type, P(0)NS-type, PNS-type, SNNS-type, SNNP(0)-type, or SNNP-type polydentate ligands and transition metal complexes of these ligands. The catalysts derived from these ligands and transition metal complexes may be used in a wide range of catalytic reactions, including hydrogenation and transfer hydrogenation of unsaturated organic compounds, dehydrogenation of alcohols and boranes, various dehydrogenative couplings, and other catalytic transformations.
Indium(III)-catalyzed one-pot synthesis of alkyl cyanides from carboxylic Acids
Moriya, Toshimitsu,Shoji, Kohei,Yoneda, Shinichiro,Ikeda, Reiko,Konakahara, Takeo,Sakai, Norio
, p. 3233 - 3238 (2013/12/04)
The one-pot preparation of alkyl cyanides from carboxylic acids via alkyl iodides or alkyl bromides, which were in situ generated either by indium(III)-catalyzed reductive iodination or bromination of carboxylic acids, is described. Georg Thieme Verlag Stuttgart New York.
Synthesis and biological evaluation of berberine-thiophenyl hybrids as multi-functional agents: Inhibition of acetylcholinesterase, butyrylcholinesterase, and Aβ aggregation and antioxidant activity
Su, Tao,Xie, Shishun,Wei, Hui,Yan, Jun,Huang, Ling,Li, Xingshu
, p. 5830 - 5840 (2013/09/12)
A series of berberine-thiophenyl hybrids were designed, synthesised, and evaluated as inhibitors of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and β-amyloid (Aβ) aggregation and as antioxidants. Among these hybrids, compounds 4f and 4i, berberine linked with o-methylthiophenyl and o-chlorothiophenyl by a 2-carbon spacer, were observed to be potent inhibitors of AChE, with IC50 values of 0.077 and 0.042 μM, respectively. Of the tested compounds, 4i was also the most potent inhibitor of BuChE, with an IC50 value of 0.662 μM. Kinetic studies and molecular modelling simulations of the AChE-inhibitor complex indicated that a mixed-competitive binding mode existed for these berberine derivatives. The biological studies also demonstrated that these hybrids displayed interesting activities, including Aβ aggregation inhibition and antioxidant properties.
Indium-catalyzed reductive bromination of carboxylic acids leading to alkyl bromides
Moriya, Toshimitsu,Yoneda, Shinichiro,Kawana, Keita,Ikeda, Reiko,Konakahara, Takeo,Sakai, Norio
supporting information, p. 4842 - 4845,4 (2020/09/16)
The combination of 1,1,3,3-tetramethyldisiloxane (TMDS) and trimethylbromosilane (Me3SiBr) with a catalytic amount of indium bromide (InBr3) undertook direct bromination of carboxylic acids, which produced the corresponding alkyl bromides in good to excellent yields. The reducing system was tolerant to several functional groups.
