58861-54-4Relevant academic research and scientific papers
Manganese-Mediated C–H Bond Activation of Fluorinated Aromatics and the ortho-Fluorine Effect: Kinetic Analysis by In Situ Infrared Spectroscopic Analysis and Time-Resolved Methods
Athavan, Gayathri,Bishop, Amy L.,Bray, Joshua T. W.,Burden, Thomas J.,Clark, Ian P.,Clarke, Francis,Eastwood, Jonathan B.,Fairlamb, Ian J. S.,Hammarback, L. Anders,Jordan, Christina,Krieger, Jean-Philippe,Lynam, Jason M.,Robinson, Alan,Towrie, Michael,Whitwood, Adrian
, p. 1532 - 1544 (2022/01/28)
Insights into the factors controlling the site selectivity of transition metal-catalyzed C–H bond functionalization reactions are vital to their successful implementation in the synthesis of complex target molecules. The introduction of fluorine atoms into substrates has the potential to deliver this selectivity. In this study, we employ spectroscopic and computational methods to demonstrate how the “ortho-fluorine effect” influences the kinetic and thermodynamic control of C–H bond activation in manganese(I)-mediated reactions. The C–H bond activation of fluorinated N,N-dimethylbenzylamines and fluorinated 2-phenylpyridines by benzyl manganese(I) pentacarbonyl BnMn(CO)5 leads to the formation of cyclomanganated tetracarbonyl complexes (2a–b and 4a–e), which all exhibit C–H bond activation ortho-to-fluorine. Corroboration of the experimental findings with density functional theory methods confirms that a kinetically controlled irreversible σ-complex-assisted metathesis mechanism is operative in these reactions. The addition of benzoic acid results in a mechanistic switch, so that cyclomanganation proceeds through a reversible AMLA-6 mechanism (kinetically and thermodynamically controlled). These stoichiometric findings are critical to catalysis, particularly subsequent insertion of a suitable acceptor substrate into the C–Mn bond of the regioisomeric cyclomanganated tetracarbonyl complex intermediates. The employment of time-resolved infrared spectroscopic analysis allowed for correlation of the rates of terminal acetylene insertion into the C–Mn bond with the relative thermodynamic stability of the regioisomeric complexes. Thus, more stable manganacycles, imparted by an ortho-fluorine substituent, exhibit a slower rate of terminal acetylene insertion, whereas a para-fluorine atom accelerates this step. A critical factor in governing C–H bond site selectivity under catalytic conditions is the generation of the regioisomeric cyclomanganated intermediates, rather than their subsequent reactivity toward alkyne insertion.
Chromium-Catalyzed Reductive Cleavage of Unactivated Aromatic and Benzylic C-O Bonds
Yuan, Shuqing,Ling, Liang,Tang, Jinghua,Luo, Meiming,Zeng, Xiaoming
, p. 3343 - 3350 (2021/07/02)
Reductive cleavage of aromatic and benzylic C-O bonds by chromium catalysis is reported. This deoxygenative reaction was promoted by low-cost CrCl 2precatalyst combined with poly(methyl hydrogen siloxane) as the mild reducing agent, providing a strategy in forming reduced motifs by cleavage of unactivated C-O bonds. A range of functional groups such as bromide, chloride, fluoride, hydroxyl, amino, and alkoxycarbonyl can be retained in the reduction.
Transition-Metal-Free Decarboxylative Arylation of 2-Picolinic Acids with Arenes under Air Conditions
Zhang, Xitao,Feng, Xiujuan,Zhou, Chuancheng,Yu, Xiaoqiang,Yamamoto, Yoshinori,Bao, Ming
supporting information, p. 7095 - 7099 (2018/11/23)
A facile, transition-metal-free, and direct decarboxylative arylation of 2-picolinic acids with simple arenes is described. The oxidative decarboxylative arylation of 2-picolinic acids with arenes proceeds readily via N-chloro carbene intermediates to afford 2-arylpyridines in satisfactory to good yields under transition-metal-free conditions. This new type of decarboxylative arylation is operationally simple and scalable and exhibits high functional-group tolerance. Various synthetically useful functional groups, such as halogen atoms, methoxycarbonyl, and nitro, remain intact during the decarboxylative arylation of 2-picolinic acids.
Metallaphotoredox-Mediated Csp2-H Hydroxylation of Arenes under Aerobic Conditions
Shah, Sk. Sheriff,Paul, Amrita,Bera, Manoranjan,Venkatesh, Yarra,Singh, N. D. Pradeep
supporting information, p. 5533 - 5536 (2018/09/21)
The direct hydroxylation of 2-arylpyridines and 2-arylbenzothiazoles via the merger of organic photoredox and metal catalysis is reported where 4CzIPN is used as the visible-light photocatalyst and Pd(OAc)2 as the metal catalyst. This method has been employed to synthesize organic molecules exhibiting excited-state intramolecular proton transfer properties for generating tunable luminescence responses.
Blue light mediated C-H arylation of heteroarenes using TiO2 as an immobilized photocatalyst in a continuous-flow microreactor
Fabry, David C.,Ho, Yee Ann,Zapf, Ralf,Tremel, Wolfgang,Panth?fer, Martin,Rueping, Magnus,Rehm, Thomas H.
supporting information, p. 1911 - 1918 (2017/06/09)
Titanium dioxide was applied as an immobilized photocatalyst in a microstructured falling film reactor for the continuous-flow C-H arylation of heteroarenes with aryldiazonium salts as the starting material. Detailed investigations of the catalyst and a successful long-term run proved its excellent usability for this process. Very good yields up to 99% were achieved with broad substrate scope and were compared with batch synthesis. The transfer to the continuous-flow mode revealed an impressive boost in reactor performance solely resulting from the improved irradiation and contact of the catalyst, substrate and light.
Fluorine-containing aromatic derivatives of selective hydrogenation reduction method
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Paragraph 0279; 0280; 0281; 0282, (2017/11/27)
The invention discloses a selective hydrogenation reduction method of a fluorine-containing aromatic hydrocarbon derivative, and particularly discloses a preparation method of a compound shown in a general formula C1, C2 or C3. The preparation method comprises the following step of: reacting a compound shown in a general formula A1, A2 or A3 with a compound shown in a general formula B in the presence of a catalyst, thus forming the compound shown in the general formula C1, C2 or C3.
Cross-coupling study of iodo/chloropyridines and 2-chloroquinoline with atom-economic triarylbismuth reagents under Pd-catalysis
Rao, Maddali L.N.,Dhanorkar, Ritesh J.
, p. 338 - 349 (2015/03/04)
This study describes the palladium-catalyzed couplings of iodopyridines, chloropyridines, and chloroquinoline with atom-economic BiAr3 reagents in sub-stoichiometric loadings. Mono-arylations of iodo and chloropyridines produced arylpyridines i
Cationic platinum(II) complexes bearing aryl-BIAN ligands: Synthesis and structural and optoelectronic characterization
Obrien, Cameron,Wong, Michael Yin,Cordes, David B.,Slawin, Alexandra M. Z.,Zysman-Colman, Eli
, p. 13 - 22 (2015/01/30)
Five cationic platinum(II) complexes bearing a 2-(3′-substituted aryl)pyridine cyclometalating ligand (C^N) and a neutral Ar-BIAN ligand have been synthesized: [Pt(ppy)(PhBIAN)]PF6 (1), [Pt(3Fppy)(PhBIAN)]PF6 (2), [Pt(3MeOppy)(PhBIAN)]PF6 (3), [Pt(3MeOppy)(4-FPhBIAN)]PF6 (4), [Pt(ppy)(4-MeOPhBIAN)]PF6 (5). All complexes have been characterized by NMR spectroscopy and mass spectrometry. Complexes 2 and 3 have been characterized by X-ray crystallography. Structure-property relationships were established from UV-visible spectroscopy and cyclic voltammetry studies. Interestingly, we found that when both the C^N and the Aryl-BIAN ligands contained electron-donating MeO groups the absorption spectrum for the platinum complex extended out to 650 nm. The electrochemical studies of these complexes established that they are electronically compatible dye molecules for dye-sensitized solar cells.
Colour tuning by the ring roundabout: [Ir(C^N)2(N^N)]+ emitters with sulfonyl-substituted cyclometallating ligands
Ertl, Cathrin D.,Cerdá, Jesús,Junquera-Hernández, José M.,Pertegás, Antonio,Bolink, Henk J.,Constable, Edwin C.,Neuburger, Markus,Ortí, Enrique,Housecroft, Catherine E.
, p. 42815 - 42827 (2015/05/27)
A series of cationic bis-cyclometallated iridium(iii) complexes [Ir(C^N)2(N^N)]+ is reported. Cyclometallating C^N ligands are based on 2-phenylpyridine with electron-withdrawing sulfone substituents in the phenyl ring: 2-(4-methylsulfonylphenyl)pyridine (H1) and 2-(3-methylsulfonylphenyl)pyridine (H2). 2-(1H-Pyrazol-1-yl)pyridine (pzpy) and 2-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (dmpzpy) are used as electron-rich ancillary N^N ligands. The complexes have been fully characterized and the single crystal structure of [Ir(2)2(dmpzpy)][PF6]·MeCN has been determined. Depending on the position of the methylsulfonyl group, the complexes are green or blue emitters with vibrationally structured emission maxima at 491, 523 nm for [Ir(1)2(N^N)][PF6] or 463, 493 nm for [Ir(2)2(N^N)][PF6] in MeCN solution. The marked vibrational structure and the absence of a rigidochromic shift, together with theoretical predictions based on density functional theory calculations, confirm the 3LC nature of the emitting triplet state. All four complexes have relatively high photoluminescence quantum yields in de-aerated solution (53 to 77%). On going from solution to powder samples, the emission is red-shifted and the quantum yields are considerably lower (≤11%). The complexes were tested in light-emitting electrochemical cells (LECs) achieving maximum luminances of 141 cd m-2 when operated at 100 A m-2 using pulsed current driving conditions.
Triarylbismuthanes as threefold aryl-transfer reagents in regioselective cross-coupling reactions with bromopyridines and quinolines
Rao, Maddali L.N.,Dhanorkar, Ritesh J.
supporting information, p. 5214 - 5228 (2014/10/15)
Cross-coupling studies using bromopyridines and bromoquinolines with triarylbismuths as threefold coupling reagents in substoichiometric amounts under Pd-catalysed conditions are disclosed. The reactivity was high with both mono- and dibromopyridyl substrates, and mono- and bis-couplings were carried out regioselectively. A library of monoaryl and diaryl pyridines was formed in high yields. A one-pot strategy provided a simple and straightforward synthesis of both symmetrical and unsymmetrical diarylpyridines. Arylations of 2-bromo- and 3-bromoquinolines were achieved with triarylbismuth reagents. This study demonstrates that triarylbismuths may be used as threefold arylating reagents for the synthesis of aryl pyridines and quinolines through couplings with bromopyridines and bromoquinolines under Pd-catalysed conditions. Copyright
