- Ni(II) catalyzed bromination of aryl C-H bonds
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Bromination of unactivated aromatic C-H bonds without directing and/or chelating groups was achieved by employing an air stable N-heterocyclic Ni(II) complex. PhI(OAC)2 and N-bromosuccinimide have been used as the oxidizing agent and the bromin
- Bhattacharya, Moumita,Cluff, David B.,Das, Siddhartha
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- Further lead optimization on Bax activators: Design, synthesis and pharmacological evaluation of 2-fluoro-fluorene derivatives for the treatment of breast cancer
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To further pursue potent Bax activators with better safety profiles for the treatment of breast cancer, structural optimization was conducted based on lead compound CYD-4-61 through several strategies, including scaffold hopping on the 2-nitro-fluorene ring, replacement of the nitro group with bioisosteres to avoid potential toxicity, and further optimization on the upper pyridine by exploring diverse alkylamine linkers as a tail or replacing the pyridine with bioisosteric heterocycles. F-containing compound 22d (GL0388) exhibited a good balance between the activity and toxicity, displaying submicromolar activities against a variety of cancer cell lines with 5.8–10.7-fold selectivity of decreased activity to MCF-10A human mammary epithelial cell line. Compound 22d dose-dependently blocked colony formation of breast cancer cells and prevented the migration and invasion of MDA-MB-231 cells. Mechanism of action studies indicate that 22d activated Bax, rendering its insertion into mitochondrial membrane, thereby leading to cytochrome c release from the mitochondria into the cytoplasm, subsequently inducing release of apoptotic biomarkers. Further in vivo efficacy studies of 22d in human breast cancer xenografts arisen from MDA-MB-231 cells demonstrated that this drug candidate significantly suppressed tumor growth, indicating the therapeutic promise of this class of compounds for the treatment of breast cancer as well as the potential for developing F-radiolabeled imaging ligands as anticancer chemical probes.
- Liu, Gang,Kim, Hyejin,Wang, Pingyuan,Fricke, Doerte R.,Chen, Haiying,Wang, Tianzhi,Shen, Qiang,Zhou, Jia
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- Synthesis of Dibenzosiloles through Electrocatalytic Sila-Friedel-Crafts Reaction
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A novel electrocatalyzed method for the preparation of dibenzosiloles was developed through intramolecular C?H/Si?H dehydrogenative coupling strategy starting from biarylhydrosilanes. Both electro-donating and electro-withdrawing substitution groups were tolerated for this transformation, and the desired dibenzosilole products could be obtained in moderate to excellent yields. A sila-Friedel-Crafts reaction mechanism was proposed on the basis of previous literature and our controlled experiments. (Figure presented.).
- Han, Pan,Yin, Mengyun,Li, Haiqiong,Yi, Jundan,Jing, Linhai,Wei, Bangguo
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supporting information
p. 2757 - 2761
(2021/04/16)
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- Palladium-catalyzed relay C–H functionalization to construct novel hybrid-arylcyclophosphorus ligand precursors
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A new relay C–H functionalization of di([1,1′-biphenyl]-2-yl)phosphine oxide to obtain esterified and hydroxylated products with different hypervalent iodines as oxidants under palladium catalysis is disclosed. This reaction provides a more effective and concise strategy for the synthesis of novel structural hybrid-arylcyclophosphorus ligand precursors with a wide range of substrates and good functional group tolerance.
- Bai, Peng-Bo,Wang, Juan,Yang, Shang-Dong
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supporting information
(2021/11/17)
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- Dephosphinylative [4 + 2] Benzannulation of Phosphinyl Ynamines: Application to the Modular Synthesis of Polycyclic Aromatic Amines
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A series of 9-amino-10-halophenanthrenes were synthesized through a one-pot process, including dephosphinylative Sonogashira–Hagihara coupling of 2-bromobiphenyls with air-stable phosphinyl ynamines, followed by halonium-promoted [4 + 2] benzannulation of the resulting 2-(aminoethynyl)biphenyls. Nonsubstituted and methyl-substituted 2-bromobiphenyls rapidly underwent the Sonogashira–Hagihara aminoethynylation and the halogenative Friedel–Crafts benzannulation to provide the corresponding amino(halo)phenanthrenes in high yields, while electron-sufficient and -deficient substrates did slowly undergo the former and the latter to result in low yields, respectively. This protocol worked well for the syntheses of highly π-extended aminophenanthrenes and aminobenzonaphthothiophenes with different optical properties. Further application of this approach between 2,2″- and 2′,5′-dibromo-p-terphenyls with phosphinyl ynamines led to the regioselective formation of 6,13-diamino-5,12-dihalo- and 5,12-diamino-6,13-dihalo-dibenz[a,h]anthracenes via dual aminoethynylation and [4 + 2] benzannulation. The obtained analogues showed different ultraviolet–visible absorption and photoluminescence spectra with different emission quantum yields in CH2Cl2 solution and the powder state.
- Okuda, Yasuhiro,Fujimoto, Mayo,Akashi, Haruo,Orita, Akihiro
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supporting information
p. 17651 - 17666
(2021/12/13)
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- Visible-Light Induced Radical Silylation for the Synthesis of Dibenzosiloles via Dehydrogenative Cyclization
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A visible-light induced radical silylation to dibenzosiloles from biarylhydrosilanes is described. The products were obtained in satisfactory yields under mild and water/air compatible conditions, providing an efficient and practical method for the synthesis of difunctionalized siloles by using a cheap organic dye photocatalyst. The method is tolerated by a wide range of functional groups and has a broad substrate scope. Light/dark experiments and quantum yield measurements provided support for a photocatalytic pathway rather than a chain process. (Figure presented.).
- Yang, Chao,Wang, Jing,Li, Jianhua,Ma, Wenchao,An, Kun,He, Wei,Jiang, Chao
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supporting information
p. 3049 - 3054
(2018/08/06)
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- Synthetic method for 9,10-benzophenanthrene compound
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The invention discloses a synthetic method for a 9,10-benzophenanthrene compound. The synthetic method comprises the following concrete steps: dissolving a compound as shown in a formula (2) which is described in the specification and another compound as shown in a formula (4) which is described in the specification in N,N-dimethyl formamide under the protection of inert gas; and carrying out a reaction at 120 to 140 DEG C under the action of copper trifluoromethanesulfonate, sodium carbonate and caesium acetate so as to obtain the 9,10-benzophenanthrene compound as shown in a formula (I) which is described in the specification. According to the invention, 2-bromobiphenyl is used as a raw material, diaryl iodate is used as an arylation reagent, bivalent copper is used as a catalyst, and sodium carbonate and caesium acetate are used as mixed base; the synthetic method has the characteristics of usage of easily available raw materials, short reaction time, high yield, etc.; and as a simplest graphene monomer, the synthesized 9,10-benzophenanthrene compound good application prospects in the field of organic photoelectricity.
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Paragraph 0066; 0067; 0068
(2018/01/09)
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- Mild, visible light-mediated decarboxylation of aryl carboxylic acids to access aryl radicals
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Herein we present the first example of aryl radical formation via the visible light-mediated decarboxylation of aryl carboxylic acids using photoredox catalysis. This method constitutes a mild protocol for the decarboxylation of cheap and abundant aryl carboxylic acids and tolerates both electron-rich substrates and those lacking ortho-substitution. The in situ formation of an acyl hypobromite is proposed to prevent unproductive hydrogen atom abstraction and trapping of the intermediate aroyloxy radical, enabling mild decarboxylation.
- Candish,Freitag,Gensch,Glorius
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p. 3618 - 3622
(2017/07/11)
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- 9-Silafluorenes via base-promoted homolytic aromatic substitution (BHAS) - The electron as a catalyst
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Transition-metal-free intramolecular radical silylation of 2-diphenylsilylbiaryls via base-promoted homolytic aromatic substitution (BHAS) to give 9-silafluorenes is reported. 2-Diphenylsilylbiaryls are readily prepared, and cross dehydrogenative silylation occurs with tert-butylhydroperoxide (TBHP) as a cheap stoichiometric oxidant in the presence of a small amount of tetrabutylammonium iodide (TBAI) as an initiator. These cyclizations are catalyzed by the electron.
- Leifert, Dirk,Studer, Armido
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supporting information
p. 386 - 389
(2015/01/30)
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- A Catalytic SEAr Approach to Dibenzosiloles Functionalized at Both Benzene Cores
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A general procedure for the catalytic preparation of dibenzosiloles functionalized at one or both benzene rings starting from readily available ortho-silylated biphenyls is reported. This method provides rapid access to silole building blocks substituted with chlorine atoms at both phenylene groups, thereby allowing catalytic access to directly polymerizable dibenzosiloles. Moreover, it is shown that, despite the involvement of highly electrophilic intermediates, a considerable range of Lewis-basic, for example, oxygen- and nitrogen-containing, functional groups is tolerated. The mechanism of this intramolecular electrophilic aromatic substitution (SEAr) proceeds through a sulfur-stabilized silicon cation, generated catalytically from the hydrosilane precursor.
- Omann, Lukas,Oestreich, Martin
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supporting information
p. 10276 - 10279
(2015/09/01)
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- Palladium-catalyzed P(O)R2 directed C-H arylation to synthesize electron-rich polyaromatic monophosphorus ligands
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Palladium-catalyzed arylation of (diisopropylphosphoryl)biphenyl skeleton derivatives by the P(O)R2 directed C-H functionalization was reported. The related products were obtained in high regioselectivity and good functional group tolerance was observed. This reaction provided a new and efficient pathway for the synthesis of polyaromatic monophosphorus ligands. The Royal Society of Chemistry.
- Hu, Rong-Bin,Zhang, Heng,Zhang, Xiao-Yu,Yang, Shang-Dong
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supporting information
p. 2193 - 2195
(2014/02/14)
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- Ni(II) catalyzed bromination of aryl C-H bonds
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Bromination of unactivated aromatic C-H bonds without directing and/or chelating groups was achieved by employing an air stable N-heterocyclic Ni(II) complex. PhI(OAC)2and N-bromosuccinimide have been used as the oxidizing agent and the bromine source, respectively. Yields for bromination are as high as >99%, especially in presence of electron-withdrawing groups like -NO2and -CF3. This is a rare report on C-H bond activation with Ni(II) where, instead of homo C-C coupling, reductive elimination to form C-halogen could be achieved.
- Bhattacharya, Moumita,Cluff, David B.,Das, Siddhartha
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p. 238 - 241
(2015/02/20)
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- Pd(II)-catalyzed C(sp2)-H hydroxylation with R 2(O)P-coordinating group
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A novel R2(O)P-directed Pd(II)-catalyzed C-H hydroxylation to synthesize various substituted 2′-phosphorylbiphenyl-2-ol compounds is described. Notably, the reaction operates under mild conditions and shows good functional group tolerance, high selectivity, and yield.
- Zhang, Hong-Yu,Yi, Hong-Ming,Wang, Gang-Wei,Yang, Bin,Yang, Shang-Dong
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supporting information
p. 6186 - 6189
(2014/01/17)
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- Palladium-catalyzed cyclocoupling of 2-halobiaryls with isocyanides via the cleavage of carbon-hydrogen bonds
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(Figure Presented) To demonstrate the utility of isocyanides in catalytic C-H bond functionalization reactions, a palladium-catalyzed cyclocoupling reaction of 2-halobiaryls with isocyanides was developed. The reaction afforded an array of fluorenone imine derivatives via the cleavage of a C-H bond at the 2′-position of 2-halobiaryls. The use of 2,6-disubstituted phenyl isocyanide was crucial for this catalytic cyclocoupling reaction to proceed. The reaction was applicable to heterocyclic and vinylic substrates, allowing the construction of a wide range of ring system. The large kinetic isotope effect observed (kH/kD = 5.3) indicates that C-H bond activation was the turnover-limiting step in this catalysis.
- Tobisu, Mamoru,Imoto, Shinya,Ito, Sana,Chatani, Naoto
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supporting information; body text
p. 4835 - 4840
(2010/10/04)
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- Ligands for metals and improved metal-catalyzed processes based thereon
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One aspect of the present invention relates to ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
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- Diastereoselective remote C-H activation by hydroboration
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Hydroboration of tetrasubstituted or trisubstituted alkenes with BH 3 and subsequent thermolysis allows remote diastereoselective C-H activation of neighboring aryl rings. Tetrasubstituted and trisubstituted 1,1-diphenyl-ethylene derivatives undergo a highly stereoselective 1,2-rearrangement followed by remote C-H activation to lead, after oxidative workup, to a diol in which the relative stereochemistry of two stereocenters has been controlled. The mechanism of this remote activation has been studied and extended to related molecules that undergo this stereoselective C-H activation, namely alkenylbiphenyl systems or alkenes with only one phenyl ring, such as alkenylbenzenes. or bicyclic systems. We have shown that this reaction allows diastereoselective synthesis of molecules with up to three contiguous chiral centers.
- Varela, Jesus A.,Pena, Diego,Goldfuss, Bernd,Denisenko, Dmitri,Kulhanek, Jiri,Polborn, Kurt,Knochel, Paul
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p. 4252 - 4264
(2007/10/03)
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- Ligands for metals and improved metal-catalyzed processes based thereon
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One aspect of the present invention relates to novel ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
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