Direct Alkynylation of Thiophenes: Cooperative Activation of TIPS–EBX with Gold and Brønsted Acids

Brand, Jonathan P.; Waser, Jérôme

doi:10.1002/ange.201003179

Cited by 79 publications

(22 citation statements)

References 53 publications

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“…Finally, a third approach based on a gold‐catalyzed Friedel–Crafts‐type addition ( b‐3 , Scheme ) has been reported. It is only successful with highly electron‐rich aromatic rings (e.g., 2,4,6‐trimethoxyphenyl groups,20 thiophenes,21 or indoles22) and electron‐poor terminal alkynes or alkynyl‐iodonium salt derivatives. In this context, Waser et al have recently described gold‐catalyzed alkynylation of indoles23 and furans24 with iodohypervalent alkynes, but this is only valid for preparing alkynes with TIPS residues.…”

Section: Introductionmentioning

confidence: 99%

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Tanase

Otaki

Nishida

et al. 2014

Chemistry A European J

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A series of tetragold(I) complexes supported by tetraphosphine ligands, meso- and rac-bis[(diphenylphosphinomethyl)phenylphosphino]methane (meso- and rac-dpmppm) were synthesized and characterized to show that the tetranuclear Au(I) alignment varies depending on syn- and anti-arrangements of the two dpmppm ligands with respect to the metal chain. The structures of syn-[Au4 (meso-dpmppm)2X]X'3 (X = Cl; X' = Cl (4 a), PF6 (4 b), BF4 (4 c)) and syn-[Au4 (meso-dpmppm)2]X4 (X = PF6 (4 d), BF4 (4 e), TfO (4 f); TfO = triflate) involved a bent tetragold(I) core with a counter anion X incorporated into the bent pocket. Complexes anti-[Au4 (meso-dpmppm)2]X4 (X = PF6 (5 d), BF4 (5 e), TfO (5 f)) contain a linearly ordered Au4 string and complexes syn-[Au4 (rac-dpmppm)2X2]X'2 (X = Cl, X' = Cl (6 a), PF6 (6 b), BF4 (6 c)) and syn-[Au4 (rac-dpmppm)2]X4 (X = PF6 (6 d), BF4 (6 e), TfO (6 f)) consist of a zigzag tetragold(I) chain supported by the two syn-arranged rac-dpmppm ligands. Complexes 4 d-f, 5 d-f, and 6 d-f with non-coordinative large anions are strongly luminescent in the solid state (λmax = 475-515 nm, Φ = 0.67-0.85) and in acetonitrile (λmax = 491-520 nm, Φ = 0.33-0.97); the emission was assigned to phosphorescence from (3) [dσ*σ*σ* pσσσ] excited state of the Au4 centers on the basis of DFT calculations as well as the long lifetime (a few μs). The emission energy is predominantly determined by the HOMO and LUMO characters of the Au4 centers, which depend on the bent (4), linear (5), and zigzag (6) alignments. The strong emissions in acetonitrile were quenched by chloride anions through simultaneous dynamic and static quenching processes, in which static binding of chloride ions to the Au4 excited species should be the most effective. The present study demonstrates that the structures of linear tetranuclear gold(I) chains can be modified by utilizing the stereoisomeric tetraphosphines, meso- and rac-dpmppm, which may lead to fine tuning of the strongly luminescent properties intrinsic to the Au(I) 4 cluster centers.

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Section: Introductionmentioning

confidence: 99%

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Tanase

Otaki

Nishida

et al. 2014

Chemistry A European J

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“…The well-known Sonogashira reaction is one of the most commonly used methods for installing alkyne moieties into (hetero)arenes molecules. [2] Recently, the direct alkynylation of (hetero)aromatic compounds has appeared as an alternative to the Sonogashira reaction by using the alkynyl reagents prepared from terminal alkynes, such as alkynyl halides, [3] benziodoxolone-based hypervalent iodine reagents, [4] or arylsulfonylacetylenes. [5] From the viewpoint of step and atom economy, the oxidative cross-coupling [6] between (hetero)arenes and terminal alkynes would be a straightforward and more efficient method for installing alkynyl groups into the (hetero)arene rings, because the need for prefunctionalization of the starting materials would be eliminated.…”

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confidence: 99%

Palladium‐Catalyzed Oxidative Cross‐Coupling between Heterocycles and Terminal Alkynes with Low Catalyst Loading

et al. 2013

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“…[9] The result of these considerations was the design of target molecule 1 (Figure 1 b). [15] We have adapted this acetylene transfer reaction for the derivatization of metalloporphyrins at the meso position. [10] Consequently, we considered unconventional alternatives for direct alkynylation and ultimately chose gold-catalyzed C À C coupling methods.…”

mentioning

confidence: 99%

Direct meso‐Alkynylation of Metalloporphyrins Through Gold Catalysis for Hemoprotein Engineering

Nierth

Marletta

2014

Angew Chem Int Ed

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A method was developed for the direct functionalization of metalloporphyrins at the methine protons (meso positions) to yield asymmetric alkynylated derivatives by using gold catalysis and hypervalent iodine reagents. This single-step procedure was applied to b-type heme and the product was incorporated into a gas-sensor heme protein. The terminal alkyne allows fluorophore labeling through copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Hemoproteins with this type of engineered cofactor have several potential applications in labeling and imaging technologies. Additionally, the alkyne provides a handle for modulating porphyrin electron density, which affects cofactor redox potential and ligand affinity. This method will be helpful for investigating the chemistry of natural heme proteins and for designing artificial variants with altered properties and reactivities.

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Direct Alkynylation of Thiophenes: Cooperative Activation of TIPS–EBX with Gold and Brønsted Acids

Cited by 79 publications

References 53 publications

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Palladium‐Catalyzed Oxidative Cross‐Coupling between Heterocycles and Terminal Alkynes with Low Catalyst Loading

Direct meso‐Alkynylation of Metalloporphyrins Through Gold Catalysis for Hemoprotein Engineering

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