Iterative Synthesis of Heterotelechelic Oligo(phenylene-vinylene)s by Olefin Cross-Metathesis

A set of experiments in surface-initiated ring-opening metathesis polymerization, including end-functionalization of growing brushes and contact angle/cyclic voltammetry measurements. We report preparation and CV of two different conjugated polymer films, and several endgroup and sidechain functionalization experiments using cross-metathesis and active ester substitution.<br>

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Synthesis of Conjugated Triynes via Alkyne Metathesis

10.26434/chemrxiv.8342534.v2 ◽

2019 ◽

Author(s):

Idriss Curbet ◽

Sophie Colombel-Rouen ◽

Romane Manguin ◽

Anthony Clermont ◽

Alexandre Quelhas ◽

...

Keyword(s):

Steric Hindrance ◽

High Selectivity ◽

Alkyne Metathesis ◽

Cross Metathesis ◽

Synthetic Strategy ◽

Sterically Hindered ◽

Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

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Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

10.26434/chemrxiv.9868196.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Ain Uddin ◽

Weifan Sang ◽

Yong Gao ◽

Kyle Plunkett

Keyword(s):

Film Formation ◽

Chemical Reduction ◽

Water Soluble ◽

Phenylene Vinylene ◽

Polymer Modification ◽

Polymer Backbone ◽

Crosslinking Process ◽

Conducting Membranes ◽

In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

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Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

10.26434/chemrxiv.9868196 ◽

2019 ◽

Author(s):

Ain Uddin ◽

Weifan Sang ◽

Yong Gao ◽

Kyle Plunkett

Keyword(s):

Film Formation ◽

Chemical Reduction ◽

Water Soluble ◽

Phenylene Vinylene ◽

Polymer Modification ◽

Polymer Backbone ◽

Crosslinking Process ◽

Conducting Membranes ◽

In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

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Concise Total Synthesis of Curvulone B

Synlett ◽

10.1055/a-1297-6838 ◽

2020 ◽

Author(s):

Debendra K. Mohapatra ◽

Shivalal Banoth ◽

Utkal Mani Choudhury ◽

Kanakaraju Marumudi ◽

Ajit C. Kunwar

Keyword(s):

Total Synthesis ◽

Stereoselective Synthesis ◽

Ring System ◽

Bond Forming ◽

Cross Metathesis ◽

Bond Forming Reactions ◽

Key Steps

AbstractA concise and convergent stereoselective synthesis of curvulone B is described. The synthesis utilized a tandem isomerization followed by C–O and C–C bond-forming reactions following Mukaiyama-type aldol conditions for the construction of the trans-2,6-disubstituted dihydropyran ring system as the key steps. Other important features of this synthesis are a cross-metathesis, epimerization, and Friedel–Crafts acylation.

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