Fluorophore tagged cross-coupling catalysts

Sashuk, Volodymyr; Schoeps, Dirk; Plenio, Herbert

doi:10.1039/b820633c

Cited by 37 publications

(23 citation statements)

References 15 publications

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“…Installation of the quaternary amino groups was envisaged by late-stagem ethylation of the nonmethylated catalyst structure to allow easier synthesis and purification. [47] Synthesiso fc arbenep recursors matching similar criteria has been reported by Plenio and co-workers, [59] and an analogous strategy was adopted in the present case ( Figure 1). Thus, electrophilic aromatic substitution between 2,6-dimethylaniline and the morpholinium ion of formaldehyde first yielded morpholine-substituted aniline 1.T reatment of 1 with glyoxal provided diimine 2,w hich on reductionw ithl ithium aluminum hydride yielded the corresponding 1,2-diamine 3.S ubsequentr ing closure of this species by using triethylo rthoformate in the presence of ammonium chloride provided imidazolinium chloride 4,s erving as the NHC ligand precursor.…”

Section: Resultssupporting

confidence: 68%

“…Installation of the quaternary amino groups was envisaged by late‐stage methylation of the nonmethylated catalyst structure to allow easier synthesis and purification . Synthesis of carbene precursors matching similar criteria has been reported by Plenio and co‐workers, and an analogous strategy was adopted in the present case (Figure ). Thus, electrophilic aromatic substitution between 2,6‐dimethylaniline and the morpholinium ion of formaldehyde first yielded morpholine‐substituted aniline 1 .…”

Section: Resultsmentioning

confidence: 70%

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Acid‐Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in Water

Timmer

Ramström

2019

Chemistry A European J

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The ability to use unprotectedc arbohydrates in olefin metathesis reactions in aqueous media is demonstrated. By using water-soluble, amine-functionalized Hoveyda-Grubbs catalysts under mildly acidic aqueousc onditions, the self-metathesis of unprotecteda lkene-functionalized a-dmanno-and a-d-galactopyranosides could be achieved through minimization of nonproductive chelation and isomerization. Cross-metathesis with allyl alcoholc ould also be achieved with reasonable selectivity. The presence of small quantities (2.5vol %) of acetic acid increased the formation of the self-metathesis product while significantly reducing the alkenei somerization process. The catalytic activityw as furthermore retained in the presenceo fl arge amounts (0.01 mm)o fp rotein, underlining the potential of this carbon-carbon bond-formingr eactionu nder biological conditions. These results demonstrate the potential of directly using unprotectedc arbohydrates tructures in olefin metathesis reactions under mild conditions compatible with biological systems, and therebye nabling their use in, for example, drug discovery and protein derivatization.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 70%

Acid‐Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in Water

Timmer

Ramström

2019

Chemistry A European J

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“…[8] Af ew of those complexes were useful for monitoring catalytict ransformations such as cross-coupling reactions, [9] olefin metathesis catalyst initiation, [10] ligand substitution reactions [8e] (Scheme 2a), gold-mediated transformation of alkynes [11] (Scheme 2b)o rc ould be applied as molecular probes for the sensing of small molecules such as CO [12] (Scheme 2c) or H 2 (Scheme2d). [8] Af ew of those complexes were useful for monitoring catalytict ransformations such as cross-coupling reactions, [9] olefin metathesis catalyst initiation, [10] ligand substitution reactions [8e] (Scheme 2a), gold-mediated transformation of alkynes [11] (Scheme 2b)o rc ould be applied as molecular probes for the sensing of small molecules such as CO [12] (Scheme 2c) or H 2 (Scheme2d).…”

Section: Introductionmentioning

confidence: 99%

Systematic Modulation of the Fluorescence Brightness in Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC)–Gold–Thiolates

Halter

Vasiuta

Fernández

et al. 2016

Chemistry A European J

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Five different highly fluorescent boron-dipyrromethene (BODIPY)-tagged N-heterocyclic carbene NHC-gold halide complexes were synthesized. The substitution of the halogeno ligand by 4-substituted aryl thiolates leads to a decrease in the brightness of the complexes. This decrease depends on the electronic nature of the thiols, being most pronounced with highly electron-rich thiols (4-R=NMe ). The brightness of the gold thiolates also depends on the distance between the sulfur atom and the BODIPY moiety. The systematic variation of the electron density of [(NHC-bodipy)Au(SC H R)] (via different R groups) enables the systematic variation of the fluorescence brightness of an appended BODIPY fluorophore. Based on this and supported by DFT calculations, a photoinduced electron-transfer quenching appears to be the dominant mechanism controlling the brightness of the appended BODIPY dye.

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“…Azolium salt 3· HCl serves as a convenient source for various NHC–metal complexes, which were prepared following the respective general literature procedures (Scheme ): [AuCl( 3 )], [PdCl(allyl)( 3 )], [PdCl 2 (Cl‐py)( 3 )], [RuCl 2 (ind)( 3 )(SIMes)],[7b] [MCl(cod)( 3 )] and [MCl(CO) 2 ( 3 )] (M = Rh, Ir) . All complexes are air‐stable solids, which can be stored under ambient conditions without decomposition.…”

Section: Resultsmentioning

confidence: 99%

“…This is compatible with a PET quenching mechanism . Based on this, Bodipy‐tagged metal complexes were found to be useful for studying reactions of catalytically active complexes in solution . This concerns the initiation of olefin metathesis catalysts, activating steps in gold‐catalyzed transformation of alkynes or the formation of dimeric metal complexes in the course of gold‐catalyzed cyclization reactions .…”

Section: Introductionmentioning

confidence: 93%

Fluorescent Dyes in Organometallic Chemistry: Coumarin‐Tagged NHC–Metal Complexes

Halter

Plenio

2018

Eur J Inorg Chem

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7-NEt 2 -and julolidene-coumarin-substituted azolium salts were synthesized and used to prepare the respective coumarin-substituted NHC-metal complexes: [AuCl(NHC)], [PdCl(allyl)(NHC)], [MCl(CO) 2 (NHC)] (M = Rh, Ir), [MCl(cod)(NHC)] (M = Rh, Ir), [PdCl 2 (Cl-py)(NHC)], [PdC(allyl)] 2 , and [RuCl 2 -(ind)(NHC)(SIMes)] -sorted according to the respective fluorescence quantum yields of between = 0.70 [Au] and = 0.005 [Ru]. The fluorescence intensity of the complexes depends on the electron density at the metal and can be increased by elec- [a] Nonetheless, Bodipy fluorophores also possess a few less favorable properties: [24] a) often small Stokes shifts are observed, as little as 10 nm are not unusual; b) treatment with strong bases causes problems with acidic protons, nucleophiles can react with the BF 2 unit; and c) typically excitation requires > 500 nm light, excitation maxima approaching 400 nm are rare. [25] It therefore appears rewarding, to look for alternatives, to complement the weaknesses of Bodipy. Coumarin is an established lipophilic fluorophore whose fluorescence properties can be designed and which has found use in numerous applications and it can be easily modified to allow UV-light excitation of the fluorescence. [26] We therefore set out to synthesize, coumarintagged organometallic complexes and to study the fluorescence properties during ligand-substitution reactions. Results and Discussion Synthesis of Coumarin-Tagged Azolium Salts and NHC-Metal ComplexesIt was decided to use 7-NEt 2 coumarins since these fluorophores are characterized by blue to ultraviolet excitation Scheme 1. Synthesis of a coumarin-substituted azolium salt (Mes = 2,4,6trimethylphenyl). Reagents and conditions: a) coumarin acid chloride 1, azolium salt 2, Et 3 N, CH 2 Cl 2 , room temp., 24 h; yield 78 %; b) 3·HBF 4 and Amberlite IRA910 Cl resin, 1:1 MeOH/CH 2 Cl 2 , room temp., overnight, yield 99 %.Scheme 2. Synthesis of coumarin-tagged NHC-metal complexes. Reagents and conditions: a) [AuCl(Me 2 S)], 3·HCl, K 2 CO 3 , 60°C, acetone; b) 3·HCl, [PdCl(allyl)] 2 and K 2 CO 3 acetone, 60°C, 4 h; c) PdCl 2 , 3·HCl, 3-Cl-pyridine solvent, K 2 CO 3 , 80°C, 24 h; d) 3·HCl, Ag 2 O, 40°C, CH 2 Cl 2 then [(SIMes)RuCl 2 (ind)(py)], (ind = 2phenylindene-1-ylidene), 60°C, toluene; e) [RhCl(cod)] 2 , acetone, 60°C, 3·HCl, K 2 CO 3 or [IrCl(cod)] 2 , CH 2 Cl 2 , 40°C, 3·HCl, Ag 2 O; f) CO, 30 min, room temp., CH 2 Cl 2 .

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Fluorophore tagged cross-coupling catalysts

Abstract: Fluorophore tagged N-heterocyclic carbenes and the derived (NHC)Pd(allyl)Cl complexes were synthesized and the fluorescence signal was used to follow the course of a Suzuki coupling reaction.

Cited by 37 publications

References 15 publications

Acid‐Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in Water

Acid‐Assisted Direct Olefin Metathesis of Unprotected Carbohydrates in Water

Systematic Modulation of the Fluorescence Brightness in Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC)–Gold–Thiolates

Fluorescent Dyes in Organometallic Chemistry: Coumarin‐Tagged NHC–Metal Complexes

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