| 1. |
- Barnå, Fredrik, et al.
(författare)
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Synthesis and crystal structures of boryl ortho-silylaryl trifluoromethanesulfonates
- 2024
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Ingår i: Acta Crystallographica Section E: Crystallographic Communications. - : International Union Of Crystallography. - 2056-9890. ; 80:2, s. 143-147
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Tidskriftsartikel (refereegranskat)abstract
- We report the synthesis and structural characterization of three crystalline borylated ortho-silylaryl trifluoromethanesulfonates: 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-(trimethylsilyl)phenyl trifluoromethanesulfonate, C16H24BF3O5SSi (1a), 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-(trimethylsilyl)phenyl trifluoromethanesulfonate, C16H24BF3O5SSi (1b), and 2-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-6-(trimethylsilyl)phenyl trifluoromethanesulfonate, C17H26BF3O5SSi (2), which are versatile aryne precursors. For all three compounds, the heteroatom substituents are almost coplanar with the central aromatic moiety. C—heteroatom bonding metrics are unexceptional and fall withing the typical range of C—B, C—Si, and C—O single bonds. Despite numerous electronegative sites, only weak intermolecular interactions are observed in the solid state.
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| 2. |
- Devaraj, Karthik, et al.
(författare)
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Arynes and Their Precursors from Arylboronic Acids via Catalytic C-H Silylation
- 2019
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Ingår i: Journal of Organic Chemistry. - : AMER CHEMICAL SOC. - 0022-3263 .- 1520-6904. ; 84:9, s. 5863-5871
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Tidskriftsartikel (refereegranskat)abstract
- A new, operationally simple approach is presented to access arynes and their fluoride-activated precursors based on Ru-catalyzed C-H silylation of arylboronates. Chromatographic purification may be deferred until after aryne capture, rendering the arylboronates de facto precursors. Access to various new arynes and their derivatives is demonstrated, including, for the first time, those based on a 2,3-carbazolyne and 2,3-fluorenyne core, which pave the way for novel derivatizations of motifs relevant to materials chemistry.
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| 3. |
- Hribersek, Matic, 1992-, et al.
(författare)
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Solvent-free and ball mill-free catalytic C–H methylation
- 2023
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Ingår i: Green Chemistry. - : RSC Publishing. - 1463-9262 .- 1463-9270. ; 25:22, s. 9138-9145
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Tidskriftsartikel (refereegranskat)abstract
- An expedient, mechanochemical, operationally simple protocol is reported for the Rh-catalysed C–H methylation of (hetero)arenes under solvent-free conditions without the use of a ball mill. Reagent mixing and activation are delivered using simple pestle-and-mortar grinding and subsequent heating, providing access to the same sustainability benefits as ball milling without the need for specialised equipment. Calculated E-factors are identical to those of ball milling and 5–25 times lower than for solution based conditions. The C–H methylation displays complete regioselectivity and good functional group tolerance. Reaction mixture analyses using scanning electron microscopy and differential scanning calorimetry are described.
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| 4. |
- Ingner, Fredric, et al.
(författare)
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Mechanochemical synthesis of (hetero)aryl Au(i) complexes
- 2020
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Ingår i: Green Chemistry. - : ROYAL SOC CHEMISTRY. - 1463-9262 .- 1463-9270. ; 22:17, s. 5648-5655
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Tidskriftsartikel (refereegranskat)abstract
- Growing demand for sustainable chemical syntheses casts mechanochemistry in a new light as an environmentally benign alternative to traditional solvent-based methods. Given recent interest in Au(i) complexes for catalytic, materials, and medicinal applications, we developed a mechanochemical protocol to prepare (hetero)aryl Au(i) complexes under green conditions. The procedure reported here uses C-H or C-B activation to afford the corresponding Au(i) complexes in high yields. Our approach bypasses external heating, long reaction times and the use of toxic solvents. We demonstrate that mechanochemical C-H auration can be used on highly functionalised bioactive substrates. Mechanistic aspects of the C-H auration are discussed.
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| 5. |
- Ingner, Fredric, et al.
(författare)
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Mild and Efficient Synthesis of Diverse Organo-Au-I-L Complexes in Green Solvents
- 2020
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Ingår i: ChemSusChem. - : WILEY-V C H VERLAG GMBH. - 1864-5631 .- 1864-564X. ; 13:8, s. 2032-2037
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Tidskriftsartikel (refereegranskat)abstract
- An exceptionally mild and efficient method was developed for the preparation of (hetero)aryl-Au-I-L complexes using ethanol or water as the reaction medium at room temperature and Ar-B(triol)K boronates as the transmetalation partner. The reaction does not need an exogeneous base or other additives, and quantitative yields can be achieved through a simple filtration as the only required purification method, which obviates considerable waste associated with alternative workup methods. A broad reaction scope was demonstrated with respect to both the L and (hetero)aryl ligands on product Au complexes. Despite the polar reaction medium, large polycyclic aromatic hydrocarbon units can be incorporated on the Au complexes in very good to excellent yields. The approach was demonstrated for the chemoselective manipulation of orthogonally protected aryl boronates to afford a new class of N-heterocyclic carbene-Au-aryl complexes. A mechanistic rationale was proposed.
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| 6. |
- Kalepu, Jagadeesh, et al.
(författare)
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C4-H indole functionalisation : precedent and prospects
- 2018
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Ingår i: Chemical Science. - : ROYAL SOC CHEMISTRY. - 2041-6520 .- 2041-6539. ; 9:18, s. 4203-4216
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Tidskriftsartikel (refereegranskat)abstract
- C4-decorated indoles feature in a plethora of bioactive and functional compounds of importance to natural product synthesis, material sciences, as well as crop protection and pharmaceutical industries. Traditionally, their syntheses largely involved harsh stoichiometric metalations and radical reactions. However, transition metal catalysed C-H activation has recently evolved into a powerful strategy for the late-stage diversification of indoles at the C4-H position. Modern photoredox, enzymatic and precious transition metal catalysis represent the key stimuli for developing challenging C-C and C-Het bond forming transformations under mild reaction conditions. Herein, we discuss the evolution and application of these methods for the step-economical transformations of otherwise inert C4-H bonds up to December 2017.
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| 7. |
- Kalepu, Jagadeesh, et al.
(författare)
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Weinreb Amides as Directing Groups for Transition Metal-Catalyzed C-H Functionalizations
- 2019
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Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 24:5
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Forskningsöversikt (refereegranskat)abstract
- Weinreb amides are a privileged, multi-functional group with well-established utility in classical synthesis. Recently, several studies have demonstrated the use of Weinreb amides as interesting substrates in transition metal-catalyzed C-H functionalization reactions. Herein, we review this part of the literature, including the metal catalysts, transformations explored so far and specific insights from mechanistic studies.
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| 8. |
- Ni, Shengjun, et al.
(författare)
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Mechanochemical Solvent-Free Catalytic C-H Methylation
- 2021
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Ingår i: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 60:12, s. 6660-6666
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Tidskriftsartikel (refereegranskat)abstract
- The mechanochemical, solvent-free, highly regioselective, rhodium-catalyzed C-H methylation of (hetero)arenes is reported. The reaction shows excellent functional-group compatibility and is demonstrated to work for the late-stage C-H methylation of biologically active compounds. The method requires no external heating and benefits from considerably shorter reaction times than previous solution-based C-H methylation protocols. Additionally, the mechanochemical approach is shown to enable the efficient synthesis of organometallic complexes that are difficult to generate conventionally.
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| 9. |
- Pilarski, Lukasz T., 1981-
(författare)
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Young Career Focus : Dr. Lukasz T. Pilarski (Uppsala University, Sweden)
- 2017
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Ingår i: Synlett. - : GEORG THIEME VERLAG KG. - 0936-5214 .- 1437-2096. ; 28:8, s. A83-A85
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background and Purpose. SYNFORM regularly meets young up-and-coming researchers who are performing exceptionally well in the arena of organic chemistry and related fields of research, in order to introduce them to the readership. This Young Career Focus presents Dr. Lukasz T. Pilarski (Uppsala University, Sweden).
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| 10. |
- Posada Urrutia, Mauricio, et al.
(författare)
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Access to long-lived room temperature phosphorescence through auration of 2,1,3-benzothiadiazole
- 2024
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry. - 1477-9226 .- 1477-9234. ; 53:12, s. 5658-5664
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Tidskriftsartikel (refereegranskat)abstract
- A series of 2,1,3-benzothiadiazole–Au(I)–L complexes have been synthesised, structurally characterised and investigated for their photophysical properties. These are the first organometallic Au(I) complexes containing a C–Au bond on the highly electron-deficient benzothiadiazole unit. The complexes exhibit solution-phase phosphorescence at room temperature, assigned to the intrinsic triplet state of the benzothiadiazole unit that is efficently populated through its attachment to gold. Comparison with routinely reported Au(I) complexes, which include intervening alkenyl linkers, suggests that previous assignments of their phosphorescence as 1π → π*(CCR) might be incomplete. Our observations affirm that, in addition to the heavy atom effect, breaking symmetry in the involved aryl motif may be of importance in controlling the luminescence properties.
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