Directional Cyclooligomers via Alkyne Metathesis

Sisco, Scott W.; Moore, Jeffrey S.

doi:10.1021/ja303572k

Cited by 26 publications

(19 citation statements)

References 23 publications

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“…Therefore we wondered if the substituents on the alkylidyneu nit of the precatalysts (aryl in 1 versus ethyl in 3)a lso playarole. To test this hypothesis, Ph 3 SiOH was added to as olution of 3 in toluene; [32] indeed, the resulting mixture wasa ble to convert the mono-TES protected substrate shown in entry 4; the conversion, however,remained incomplete (ca. 60 %) and am ixture of the desired cyclic monomer and the cyclic dimer was formed, whereas 3/ 11 b afforded the product in an isolated yield of 64 %.…”

Section: Propargylic and Bis-propargylic Alcohold Erivativesmentioning

confidence: 99%

A Two‐Component Alkyne Metathesis Catalyst System with an Improved Substrate Scope and Functional Group Tolerance: Development and Applications to Natural Product Synthesis

Schaubach

Gebauer

Ungeheuer

et al. 2016

Chemistry A European J

101

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Although molybdenum alkylidyne complexes such as 1 endowed with triarylsilanolate ligands are excellent catalysts for alkyne metathesis, they can encounter limitations when (multiple) protic sites are present in a given substrate and/or when forcing conditions are necessary. In such cases, a catalyst formed in situ upon mixing of the trisamidomolybenum alkylidyne complex 3 and the readily available trisilanol derivatives 8 or 11 shows significantly better performance. This two-component system worked well for a series of model compounds comprising primary, secondary or phenolic -OH groups, as well as for a set of challenging (bis)propargylic substrates. Its remarkable efficiency is also evident from applications to the total syntheses of manshurolide, a highly strained sesquiterpene lactone with kinase inhibitory activity, and the structurally demanding immunosuppressive cyclodiyne ivorenolide A; in either case, the standard catalyst 1 largely failed to effect the critical macrocyclization, whereas the two-component system was fully operative. A study directed toward the quinolizidine alkaloid lythrancepine I features yet another instructive example, in that a triyne substrate was metathesized with the help of 3/11 such that two of the triple bonds participated in ring closure, while the third one passed uncompromised. As a spin-off of this project, a much improved ruthenium catalyst for the redox isomerization of propargyl alcohols to the corresponding enones was developed

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Section: Propargylic and Bis-propargylic Alcohold Erivativesmentioning

confidence: 99%

A Two‐Component Alkyne Metathesis Catalyst System with an Improved Substrate Scope and Functional Group Tolerance: Development and Applications to Natural Product Synthesis

Schaubach

Gebauer

Ungeheuer

et al. 2016

Chemistry A European J

101

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“…Under these irradiation conditions, cyclic oligomers of DP ¼ 1, 2 and 3 are obtained aer 24 h. Cyclodepolymerizations have already been described by Carothers as a synthetic route towards macrocyclic oligomers on the basis of polyesters 55 and usually require high temperatures 20 and catalysts. 33,56 To date, however, photochemically induced cyclodepolymerizations have not been reported. 20 Owing to the different depolymerization conditions of P1 under violet or UVB light, the observed oligomers have different topologies and elution times in the SEC.…”

Section: Wavelength-gated Depolymerizationmentioning

confidence: 99%

Wavelength-Gated Photoreversible Polymerization and Topology Control

Frisch¹,

Mundsinger²,

Poad³

et al. 2020

Preprint

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We exploit the wavelength dependence of [2 + 2] photocycloadditions and -reversions of styrylpyrene to exert unprecedented control over the photoreversible polymerization and topology of telechelic building blocks. Blue light (l max ¼ 460 nm) initiates a catalyst-free polymerization yielding high molar mass polymers (M n ¼ 60 000 g mol À1 ), which are stable at wavelengths exceeding 430 nm, yet highly responsive to shorter wavelengths. UVB irradiation (l max ¼ 330 nm) induces a rapid depolymerization affording linear oligomers, whereas violet light (l max ¼ 410 nm) generates cyclic entities. Thus, different colors of light allow switching between a depolymerization that either proceeds through cyclic or linear topologies. The light-controlled topology formation was evidenced by correlation of mass spectrometry (MS) with size exclusion chromatography (SEC) and ion mobility data. Critically, the color-guided topology control was also possible with ambient laboratory light affording cyclic oligomers, while sunlight activated the linear depolymerization pathway. These findings suggest that light not only induces polymerization and depolymerization but that its color can control the topological outcomes. Results and discussion Cyclization and linearizationTo give access to wavelength controlled dynamic covalent bonds, the photochemistry of the stilbene derivative styrylpyrene was Scheme 1 (A) Chemical structure of the reversible [2 + 2] photocycloaddition of styrylpyrene used as a wavelength gated binding site of telechelic polymers. (B) Action plot for the conversion of the photocycloaddition (black cubes) and the photocycloreversion of the cycloadduct (red cubes) after irradiation with the same number of photons at different wavelengths, as previously reported for the styrylpyrene derivative hydroxyl-styrylpyrene. 42 The normalized emission spectra of the herein utilized UVB lamp (grey) and LEDs (violet, l max ¼ 410 nm and blue, l max ¼ 460 nm) indicate which reaction is triggered in the respective photonic field. (C) Schematic representation of the polymerization and depolymerization of L1 comprising two terminal styrylpyrene units. Irradiation of L1 with blue light induces its photopolymerization yielding P1, which can be either cyclodepolymerized under violet light or linearly depolymerized under UVB light.This journal is Fig. 4 Depolymerization of P1 (black) into linear oligomers (highlighted in red) within 4 min of sunlight irradiation.This journal is

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“…To test whether there was a thermodynamic preference for directional precursors, two alkynyl‐polymers, MM and OP, were designed and synthesized with incorporated directionality as a result of their ester linkages [Fig. (a)] . Depolymerization‐macrocyclization of MM afforded a broad product distribution comprising 17% of a 1:3 statistical mixture of both possible constitutional isomers of MM‐[3]mer (MM‐A 3 and MM‐A 2 B) .…”

Section: Alkyne Metathesismentioning

confidence: 99%

“…46 Depolymerization-macrocyclization of MM afforded a broad product distribution comprising 17% of a 1:3 statistical mixture of both possible constitutional isomers of MM- [3]mer (MM-A 3 and MM-A 2 B). 46 On the other hand, depolymerization-macrocyclization of the OP polymer resulted in a sharp product distribution with only the directionallyuniform cyclic trimer and tetramer (OP- [3]mer and OP- [4]mer) isolated. 46 This work represents the importance of carefully designing precursors to achieve controlled macrocyclic formation.…”

Section: Highlightmentioning

confidence: 99%

See 1 more Smart Citation

Grubbs‐inspired metathesis in the Moore group

Moneypenny

Liu

Yang

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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Alkene metathesis has proven to be a powerful method for carbonAcarbon bond formation, particularly in the field of polymer and materials science. The availability of various tailor-made catalysts not only enables the synthesis of well-defined polymers but facilitates the development of functional, stimuli-responsive materials. This highlight, dedicated to Professor Robert Grubbs on his 75th birthday, focuses on the various research efforts in our group utilizing both alkene and alkyne metatheses and the interesting materials derived from them.

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Directional Cyclooligomers via Alkyne Metathesis

Cited by 26 publications

References 23 publications

A Two‐Component Alkyne Metathesis Catalyst System with an Improved Substrate Scope and Functional Group Tolerance: Development and Applications to Natural Product Synthesis

A Two‐Component Alkyne Metathesis Catalyst System with an Improved Substrate Scope and Functional Group Tolerance: Development and Applications to Natural Product Synthesis

Wavelength-Gated Photoreversible Polymerization and Topology Control

Grubbs‐inspired metathesis in the Moore group

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