Alkylating Polymers: Resin-Released Carbenium Ions as Versatile Reactive Intermediates in Polymer-Assisted Solution-Phase Synthesis

Rademann, Jörg; Smerdka, Joachim; Jung, Günther; Grosche, Philipp; Schmid, Dietmar G.

doi:10.1002/1521-3773(20010119)40:2<381::aid-anie381>3.0.co;2-v

Cited by 57 publications

(19 citation statements)

References 14 publications

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“…Answering these questions is particularly important to drive progressi na lkylation technology and the synthesis and understandingo fc ustom reagents for niche applications.F or example, solid-supported alkylators are finding applications in flowchemistry since they eliminate the need for side product removal, simplify purification, and reimagine the role of alkylation reaction in complex reactor setups. [14,15] Other "smart"a lkylation technologiesr ely on the use of triggerss uch as light, [16,17] certaine nzymes, [18,19] and electrophiles, [20] which provides both temporal and spatial control over the alkylation process. Semi-stable cations capable of controlled transalkylation have led to the discoveryo fa ne ntirely new class of polymer vitrimers pioneered by Drockenmuller et al [21] and demonstrates an on-conventional use for cationic alkylators beyond synthesis.…”

Section: Introductionmentioning

confidence: 99%

Not‐So‐Innocent Anions Determine the Mechanism of Cationic Alkylators

Taimoory

Cataldo

Schäfer

et al. 2021

Chemistry A European J

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Alkylating reagents based on thioimidazolium ionic liquids were synthesized and the influence of the anion on the alkylation reaction mechanism explored in detail using both experimental and computational methods. Thioimidazolium cations transfer alkyl substituents to nucleophiles, however the reaction rate was highly dependent on anion identity, demonstrating that the anion is not innocent in the mechanism. Detailed analysis of the computationally‐derived potential energy surfaces associated with possible mechanisms indicated that this dependence arises from a combination of anion induced electronic, steric and coordinating effects, with highly nucleophilic anions catalyzing a 2‐step process while highly non‐nucleophilic, delocalized anions favor a 1‐step reaction. This work also confirms the presence of ion‐pairs and aggregates in solution thus supporting anion‐induced control over the reaction rate and mechanism. These findings provide new insight into an old reaction allowing for better design of cationic alkylators in synthesis, gene expression, polymer science, and protein chemistry applications.

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Section: Introductionmentioning

confidence: 99%

Not‐So‐Innocent Anions Determine the Mechanism of Cationic Alkylators

Taimoory

Cataldo

Schäfer

et al. 2021

Chemistry A European J

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“…The rich chemistry of the BODIPY fluorophore was employed to construct the energy donor (parent structure) and the energy acceptor (emitter, styryl-BODIPY) of the FRET pair (Scheme 1) from BODIPY. 10,11,39 The probe is non-fluorescent but a red emission at 590 nm is switched on in the presence of cysteine. A large Stokes shift was observed for the probe emission, the probe displays an intense absorption at 513 nm (due to the FRET donor) and red-emission at 590 nm (FRET acceptor), thus a pseudo-Stokes shift is up to 77 nm is observed.…”

Section: Introductionmentioning

confidence: 99%

A highly selective red-emitting FRET fluorescent molecular probe derived from BODIPY for the detection of cysteine and homocysteine: an experimental and theoretical study

et al. 2012

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A red-emitting BODIPY-based fluorescent-resonance-energy-transfer (FRET) molecular probe 1 for selective detection of cysteine and homocysteine was designed. The fluorescence OFF-ON switch is triggered by cleavage of the 2,4-dinitrobenzensulfonyl (DNBS) unit from the fluorophore by thiols. The FRET energy donor (l abs ¼ 498 nm, l em ¼ 511 nm) is a parent BODIPY moiety and the energy acceptor is based on 4-hydroxylstyryl BODIPY moiety (l abs ¼ 568 nm, l em ¼ 586 nm). The unique C-C linker between the energy donor and acceptor was established using a Suzuki cross-coupling reaction. A polyether chain was also introduced into the probe to improve solubility in aqueous solution. While probe 1 itself is non-fluorescent, in the presence of cysteine or homocysteine a red emission at 590 nm is switched on (excitation at 505 nm), producing a pseudo-Stokes shift of up to 77 nm, which is in stark contrast to the small Stokes shift (ca. 10 nm) observed for typical BODIPY dyes. Excitation of the energy donor leads to the red emission from the acceptor of the probe, and demonstrates a high energy transfer efficiency. The probe was used for in vivo fluorescent imaging of cellular thiols. The fluorescence sensing mechanism of the probe and the photophysical properties of the fluorescent intermediates were fully rationalized by DFT calculations. The lack of fluorescence of probe 1 is attributed to the dark excited state S 1 (oscillator strength f ¼ 0.0007 for S 0 / S 1 , based on the optimized S 1 state geometry), which is due to the electron sink effect of the DNBS moiety. Cleavage of the DNBS moiety from the fluorophore by thiols re-establishes the emissive S 1 state of the fluorophore (f ¼ 1.4317 for S 0 / S 1 ), thus the red emission can be observed in the presence of thiols (fluorescence is turned on). The FRET effect of the probe was rationalized by DFT calculations which indicated that upon excitation into the S 4 excited state (localized on the energy donor unit), the S 1 state (localized on the energy acceptor, i.e. styryl-BODIPY) is populated via internal conversion (IC), thus red emission from the styryl-BODIPY energy acceptor is observed (Kasha's rule).

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“…A series of papers on the use of FTICR-MS for combinatorial library analysis was published by Jung's group at the University of Tübingen [30,31,32,33]. In 1999, Walk et al [30] compared the performance of FTICR-MS with that of quadrupole mass spectrometers for combinatorial library analysis.…”

Section: Direct Fticr-ms Analysis Of Combinatorial Librariesmentioning

confidence: 93%

“…8). Rademann et al [33] describe an investigation of novel alkylating polymers for polymer-assisted solution-phase combinatorial syntheses. Among other applications an equimolar mixture of 20 pyrazolecarboxylic acids was synthesized by the split-and-mix approach [31,32] and treated with the novel reactive polymer to yield the methyl esters.…”

Section: Direct Fticr-ms Analysis Of Combinatorial Librariesmentioning

confidence: 99%

Ultra-high resolution for mass spectrometric analysis of complex and low-abundance mixtures – the emergence of FTICR-MS as an essential analytical tool

2002

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The role of high resolution in mass spectrometric analysisThe development of applications of mass spectrometry to chemical analysis has followed several paths, such as invention of new techniques for ionization, for acquisition of additional information concerning the relationship between fragment ions in the spectrum (tandem mass spectrometry), and for on-line coupling of a mass spectrometer to separatory techniques for real-time mixture analysis. Other features of any analytical instrument, such as sensitivity and detection limits, spectral acquisition rate, m/z range, etc., have, in mass spectrometry, often been driven by the need to match the low sample levels and higher resolution which have resulted from the introduction of capillary-based chromatographic methods.This article, however, is concerned with another figure-of-merit, the resolving power of the mass spectrometer itself. Historically, the need for higher resolving power was driven by investigations into isotopic compositions of the elements after Aston's landmark discoveries. Magnetic sector instruments were the dominant technology, and the invention of the double-focusing principle enabled simultaneous achievement of large increases in sensitivity and resolving power, counter-intuitive for a dispersion analyzer. The desire to detect and measure extremely low levels of rare isotopes, the mass spectral peaks of which were adjacent to those of much more abundant isotopes, required high resolving power, defined in terms of peak widths near the base of the peaks, to achieve the required "abundance sensitivity" for the rare

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Alkylating Polymers: Resin-Released Carbenium Ions as Versatile Reactive Intermediates in Polymer-Assisted Solution-Phase Synthesis

Cited by 57 publications

References 14 publications

Not‐So‐Innocent Anions Determine the Mechanism of Cationic Alkylators

Not‐So‐Innocent Anions Determine the Mechanism of Cationic Alkylators

A highly selective red-emitting FRET fluorescent molecular probe derived from BODIPY for the detection of cysteine and homocysteine: an experimental and theoretical study

Ultra-high resolution for mass spectrometric analysis of complex and low-abundance mixtures – the emergence of FTICR-MS as an essential analytical tool

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