Advanced Materials and Forms: Photosensitive Metathesis Polymers

Mühlebach, Andreas; Schaedeli, U.

doi:10.1021/bk-1996-0620.ch028

Cited by 3 publications

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“…Also, the judicious choice of the CTA such that metathesis with the CTA does not lead to a substituted alkylidene that is unstable is important to catalyst efficiency. For both molybdenum- and tungsten-based metathesis catalysts, this typically requires the separation of the functional group from the olefin in the CTA to be at least two methylene units. , The synthesis of CTAs with protected functionalities that are well-removed from the olefin is one limitation in these metathesis techniques for the preparation of end-functionalized polymers . We now report that a neat mixture of cycoloctadiene (COD) and the simple allylic CTA ( 1 ) can be polymerized using a ruthenium-based metathesis catalyst (Ru) to yield difunctional 1,4-polybutadiene (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

“…1,5 The synthesis of CTAs with protected functionalities that are well-removed from the olefin is one limitation in these metathesis techniques for the preparation of end-functionalized polymers. 6 We now report that a neat mixture of cycoloctadiene (COD) and the simple allylic CTA (1) can be polymerized using a rutheniumbased metathesis catalyst (Ru) 7 to yield difunctional 1,4polybutadiene (Scheme 1). The acetate end groups can be removed under mild conditions in high yield to give the commercially important hydroxytelechelic polybutadiene (HTPBD).…”

Section: Introductionmentioning

confidence: 99%

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Utility of a Ruthenium Metathesis Catalyst for the Preparation of End-Functionalized Polybutadiene

1997

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The polymerization of cyclooctadiene (COD) in the presence of an allylic difunctionalized chain transfer agent (1) by a ruthenium metathesis catalyst (Ru) was accomplished. Deprotection of the resulting acetate end-functionalized polybutadiene was performed, leading to commercially important 1,4-hydroxytelechelic polybutadiene (HTPBD) with number average functionalities close to 2.0. The polymerizations were performed at high monomer concentrations or in the absence of solvent, and the robust nature of Ru allowed the use of high monomer to catalyst ratios (∼0.01 mol % Ru relative to total olefin). Investigation of the metathesis of olefin alcohols with Ru showed that side reactions may complicate the use of these compounds as chain transfer agents in metathesis polymerizations. The kinetics of this Ru-catalyzed ring-opening metathesis polymerization with added chain transfer agent was also investigated.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Utility of a Ruthenium Metathesis Catalyst for the Preparation of End-Functionalized Polybutadiene

1997

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Einkomponentige Katalysatoren für die thermische und photoinduzierte Ringöffnungs‐Metathese‐Polymerisation

Hafner¹,

Mühlebach²,

Schaaf³

1997

Angewandte Chemie

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One‐Component Catalysts for Thermal and Photoinduced Ring Opening Metathesis Polymerization

Hafner¹,

Mühlebach²,

Schaaf³

1997

Angew. Chem. Int. Ed. Engl.

161

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COMMUNICATIONSa single diastereorner by chromatography. The sense of asymmetric induction in this cycloaddition is consistent with a Lewis acid catalyzed Diels-Alder reaction on the s-cis ZnBr, complex 8a.In analogy to previous experiments, Diels-Alder adduct 9 was transformed to the corresponding P-ketothioester in 90% yield and smoothly decarboxylated (70 "C, 24 h) to afford ketone 10 in 86% yield without epimerization at the ring fusion. The synthesis was completed by treatment of 10 with Tebbe reagent"81 to afford synthetic a-himachalene (11) (92% yield), whose spectroscopic and analytical data are identical in all respects to literature values ('HNMR, IR, TLC, [a]D).[151The removable auxiliary X = COX, described here should prove useful in enantioselective ketone-based bond constructions. Although the methodology has been highlighted with al-do1 and Diels-Alder reactions, absolute stereochemical control of other transformations such as the Michael reaction should also be possible. Studies extending the scope of these concepts are currently underway. Experimental SectionGeneral one-flask procedure for the decarboxylation of b-ketoimides: A stirred suspension of KH (1.2 mmol) in THF (10 mL) under argon was charged with EtSH (1 3 mmol) and gas evolved. The white suspension was stirred for 1 h before a solution of /I-oxoimide (1 mmol) in THF (10 mL) was added by cannula. The reaction mixture was stirred until the starting material had been consumed. To the reaction mixture was added water (4 mL) and 2,6-lutidine (10 mmol), followed by AgNO, (2.5 mmol). The reaction mixture was protected from light and stirred for two days. The pale yellow suspension was filtered through Celite with ether, and the organic solution was extracted between ether (50 mL) and aqueous CuSO, solution (50 mL). The ether layer was separated, dried over MgSO,, and concentrated in vacuo. Chromatography on silica gel using an appropriate solvent mixture provided pure ketone.

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Advanced Materials and Forms: Photosensitive Metathesis Polymers

Cited by 3 publications

References 1 publication

Utility of a Ruthenium Metathesis Catalyst for the Preparation of End-Functionalized Polybutadiene

Utility of a Ruthenium Metathesis Catalyst for the Preparation of End-Functionalized Polybutadiene

Einkomponentige Katalysatoren für die thermische und photoinduzierte Ringöffnungs‐Metathese‐Polymerisation

One‐Component Catalysts for Thermal and Photoinduced Ring Opening Metathesis Polymerization

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