Diversifying Polyhydroxyalkanoates – End-Group and Side-Chain Functionality

2017 ◽  
Vol 14 (6) ◽  
pp. 757-767 ◽  
Author(s):  
Michal Michalak ◽  
Iwona Kwiecien ◽  
Michal Kwiecien ◽  
Grazyna Adamus ◽  
Karin Odelius ◽  
...  
Keyword(s):  
Functional Groups ◽  
Polymer Chain ◽  
Ring Opening ◽  
Functional Group ◽  
Side Chain ◽  
Natural Origin ◽  
Polymer Formation ◽  
End Groups ◽  
Group Diversity ◽  
End Group

Background: Polyhydroxyalkanoates (PHAs) are a natural origin biodegradable polyesters consisted of various 3- and 4-hydroxyacid derived repeating units produced by microorganisms as energy storage. PHAs have been intensively studied due to their biodegradability and biocompatibility enabling their use both in packaging and agriculture as well as in medicine and pharmacy. PHAs obtained via biotechnological routes can possess various functional groups in their side chains. However, the diversity in their functionality is limited due to issues of conservation of functional groups during the polymer formation. Objective: The review focuses on recent progress in the area of synthesis of PHAs functionalized with various reactive as well as bioactive end and side groups. Conclusion: A potent route to resolve the problem of functional group diversity in natural origin PHAs involves post-polymerization modification, where the desired side groups can be created. On the contrary, synthetically produced PHA analogs obtained directly via ring-opening polymerization of β-lactones offer various functionalities at different position throughout the polymer chain. The desired α- and ω-end groups can be introduced into the polymer chain using specific polymerization, initiation or termination strategies, respectively. The preferred side chain functionality is obtained by choosing the appropriate β-lactone monomers bearing respective functional groups. All functional groups may also be subjected to additional chemical modification. The degradation of PHA as a method for producing functional polymers as well as their possible further applications are also discussed.

Dissociation States of Collagen Functional Groups and their Effects on the Priming Efficacy of HEMA Bonded to Collagen

2003 ◽  
Vol 82 (4) ◽  
pp. 257-261 ◽  
Author(s):  
N. Nishiyama ◽  
K. Suzuki ◽  
A. Nagatsuka ◽  
I. Yokota ◽  
K. Nemoto
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Bond Strength ◽  
Functional Groups ◽  
Functional Group ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Bonding Agents

Applying 2-hydroxyethylmethacrylate (HEMA) solution to etched dentin enhances the bonding of resin to dentin. However, the principal adhesion mechanisms have not yet been identified. In this study, we examined the dissociation states of the collagen functional groups of the side-chain amino acid residues and their effects on the bond strength of resin to etched dentin primed by the HEMA solution. The bond strength was strongly dependent upon the dissociation state of the collagen functional groups. Inhibiting the dissociation of the carboxylic acid or the amine of a collagen functional group resulted in increased bond strength of resin to collagen. By understanding the significance of inhibiting the dissociation state, we can better design and develop more effective and efficient primer and bonding agents.

scholarly journals Functional End Groups in Living Ring-Opening Metathesis Polymerization

Synlett ◽  
2019 ◽  
Vol 30 (18) ◽  
pp. 2051-2057 ◽  
Author(s):  
Andreas F. M. Kilbinger
Keyword(s):  
Functional Groups ◽  
Research Group ◽  
Ring Opening ◽  
Synthetic Methods ◽  
Personal Account ◽  
Ring Opening Metathesis Polymerization ◽  
Metathesis Polymerization ◽  
End Groups ◽  
Polymerization Method

Over the last two decades many synthetic methods have been reported to selectively introduce a number of different functional groups at the chain end of a living ring-opening metathesis polymer. In this personal account, I would like to focus on a few such methods developed in my research group over the last several years and how these led to the discovery of catalytic living ring-opening metathesis polymerization, a ring-opening metathesis polymerization method controlled by the polymer end groups. This account consists of the following sections:1 Introduction2 Functionalization of the Propagating Chain End3 Functionalization of the Initiating Chain End4 Polymerization Control by Functional End Groups5 Conclusions

scholarly journals Enhancing the conjugation yield of brush polymer–protein conjugates by increasing the linker length at the polymer end-group

2016 ◽  
Vol 7 (13) ◽  
pp. 2352-2357 ◽  
Author(s):  
Peter C. Nauka ◽  
Juneyoung Lee ◽  
Heather D. Maynard
Keyword(s):  
Side Chain ◽  
Linker Length ◽  
Protein Conjugates ◽  
Protein Conjugate ◽  
Brush Polymer ◽  
End Groups ◽  
End Group

Increasing the linker length between oligoPEG side chain polymers and end groups can enhance the yield of the protein conjugate.

A Robust, Open-Flask, Moisture-Tolerant, and Scalable Route to Unprotected α/β-Amino Acid N-Carboxyanhydrides

2020 ◽  
Author(s):  
Zi-You Tian ◽  
HUA LU
Keyword(s):  
Amino Acid ◽  
Functional Groups ◽  
Ring Opening ◽  
Biomedical Applications ◽  
Functional Group ◽  
Ring Opening Polymerization ◽  
High Yield ◽  
Synthetic Polypeptides ◽  
Acid Catalyzed ◽  
Hydroxyl Acid

Synthetic polypeptides, commonly prepared by the ring-opening polymerization (ROP) of amino acid N-carboxyanhydrides (NCA), are a family of biomimetic materials with vast biomedical applications. A great hurdle in the pro-duction of synthetic polypeptides is the synthesis of NCA, which requires ultra-dry solvents, Schlenk line/gloveboxes, and the protection of sidechain functional groups. Herein, we report a robust and scalable new method for the production of unpro-tected NCA monomers in air and under moisture. The method employs propylene oxide or epichlorohydrin as an inexpensive and ultra-fast scavenger of hydrogen chloride to prevent NCA from acid-catalyzed decomposition under moist conditions. The broad scope and outstanding functional group tolerance of the method are demonstrated by the successful synthesis of more than 30 different NCAs, including many otherwise inaccessible compounds with reactive functional groups (e.g. hy-droxyl, thiol, and carboxylic acid), at high yield and up to ten-gram scale. The scope of the method can be further extended to various α-hydroxyl acid O-carboxyanhydrides (OCA) and β-amino acid NCAs (βNCA). Given these merits, our strategy holds great potential for revolutionizing the synthesis of NCA and polypeptides, and dramatically expanding the industrial application of synthetic polypeptides

scholarly journals Functional group diversity by ruthenium-catalyzed olefin cross-metathesis

2002 ◽  
Vol 74 (1) ◽  
pp. 7-10 ◽  
Author(s):  
F. Dean Toste ◽  
Arnab K. Chatterjee ◽  
Robert H. Grubbs
Keyword(s):  
Functional Groups ◽  
Functional Group ◽  
Chiral Ligands ◽  
Cross Metathesis ◽  
Wide Range ◽  
Group Diversity ◽  
High Degree

Ruthenium-catalyzed olefin cross-metathesis tolerates a wide range of functional groups, including phosphine-boranes, sulfides, amines, phenols, and oxazolines. The high functional group tolerance allows for the use of an olefin as a linchpin for the synthesis of a variety of bi-, tri-, and tetradentate chiral ligands with a high degree of functional group diversity.

scholarly journals Domino ring-opening–ring-closing enyne metathesis vs enyne metathesis of norbornene derivatives with alkynyl side chains. Construction of condensed polycarbocycles

2018 ◽  
Vol 14 ◽  
pp. 2708-2714 ◽  
Author(s):  
Ritabrata Datta ◽  
Subrata Ghosh
Keyword(s):  
Ring Opening ◽  
Functional Group ◽  
Domino Reaction ◽  
Side Chain ◽  
Side Chains ◽  
Enyne Metathesis ◽  
Substrate Structure ◽  
Norbornene Derivatives

The metathesis of norbornene derivatives with alkynyl side-chain with Grubbs’ ruthenium alkylidine as catalyst has been investigated with the objective of constructing condensed polycyclic structures. This investigation demonstrated that the generally observed domino reaction course involving a ring-opening metathesis of the norbornene unit and a ring-closing enyne metathesis is influenced to a great extent by the nature of the functional group and the substrate structure and may follow a different reaction course than what is usually observed. In cases where ROM–RCEYM occurred, the resulting 1,3-diene reacts in situ with the dienophile to provide condensed tetracyclic systems.

scholarly journals Effect of Side Chain Functional Groups on the DPPH Radical Scavenging Activity of Bisabolane-Type Phenols

Antioxidants ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 65 ◽  
Author(s):  
Kazuya Ichikawa ◽  
Ryosuke Sasada ◽  
Kosuke Chiba ◽  
Hiroaki Gotoh
Keyword(s):  
Functional Groups ◽  
Aromatic Ring ◽  
Functional Group ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Side Chain ◽  
Scavenging Activity ◽  
Dpph Radical ◽  
Dpph Radical Scavenging Activity ◽  
Dpph Radical Scavenging

Methods for improving the antioxidant activity of phenolic compounds have been widely investigated; however, most studies have focused on the structure–activity correlations of substituents on the aromatic rings of catechols or flavonoids. We investigated the influence of side chain functional groups on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of xanthorrhizol and curcuphenol analogues. These compounds were synthesised by the side chain functional group conversion of curcumene, followed by direct oxidation of the aromatic ring. We determined the DPPH radical scavenging activity from the half-maximal effective concentration (EC50) obtained from a DPPH assay in methanol. The positional relationships of the side chain with the aromatic ring and phenolic OH group were determined using density functional theory calculations, and the stability of different conformations was compared. Electron transfer-proton transfer was determined to be the dominant mechanism in the DPPH reaction with xanthorrhizol analogues, based on the correlation between the EC50 and ionisation potential. The radical cation was greatly stabilised in the structure where the side chain functional group was close to the aromatic ring. Stabilisation also depended on the phenolic OH group position. In future antioxidant design, aromatic ring substituent conversion and the use of functional groups far from the OH group or ring should be explored.

scholarly journals A Robust, Open-Flask, Moisture-Tolerant, and Scalable Route to Unprotected α/β-Amino Acid N-Carboxyanhydrides

2020 ◽  
Author(s):  
Zi-You Tian ◽  
HUA LU
Keyword(s):  
Amino Acid ◽  
Functional Groups ◽  
Ring Opening ◽  
Biomedical Applications ◽  
Functional Group ◽  
Ring Opening Polymerization ◽  
High Yield ◽  
Synthetic Polypeptides ◽  
Acid Catalyzed ◽  
Hydroxyl Acid

Synthetic polypeptides, commonly prepared by the ring-opening polymerization (ROP) of amino acid N-carboxyanhydrides (NCA), are a family of biomimetic materials with vast biomedical applications. A great hurdle in the pro-duction of synthetic polypeptides is the synthesis of NCA, which requires ultra-dry solvents, Schlenk line/gloveboxes, and the protection of sidechain functional groups. Herein, we report a robust and scalable new method for the production of unpro-tected NCA monomers in air and under moisture. The method employs propylene oxide or epichlorohydrin as an inexpensive and ultra-fast scavenger of hydrogen chloride to prevent NCA from acid-catalyzed decomposition under moist conditions. The broad scope and outstanding functional group tolerance of the method are demonstrated by the successful synthesis of more than 30 different NCAs, including many otherwise inaccessible compounds with reactive functional groups (e.g. hy-droxyl, thiol, and carboxylic acid), at high yield and up to ten-gram scale. The scope of the method can be further extended to various α-hydroxyl acid O-carboxyanhydrides (OCA) and β-amino acid NCAs (βNCA). Given these merits, our strategy holds great potential for revolutionizing the synthesis of NCA and polypeptides, and dramatically expanding the industrial application of synthetic polypeptides

Visible Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones

2019 ◽  
Author(s):  
Marharyta V. Laktsevich-Iskryk ◽  
Nastassia A. Varabyeva ◽  
Volha V. Kazlova ◽  
Vladimir N. Zhabinskii ◽  
Vladimir A. Khripach ◽  
...  
Keyword(s):  
Visible Light ◽  
Functional Groups ◽  
Ring Opening ◽  
Radical Intermediates ◽  
Reaction Proceeds

In this article, we report a photocatalytic protocol for the isomerization of 1,2-disubstituted cyclopropanols to linear ketones. The reaction proceeds <i>via</i> radical intermediates and tolerates various functional groups.

Visible Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones

2019 ◽  
Author(s):  
Marharyta V. Laktsevich-Iskryk ◽  
Nastassia A. Varabyeva ◽  
Volha V. Kazlova ◽  
Vladimir N. Zhabinskii ◽  
Vladimir A. Khripach ◽  
...  
Keyword(s):  
Visible Light ◽  
Functional Groups ◽  
Ring Opening ◽  
Radical Intermediates ◽  
Reaction Proceeds

In this article, we report a photocatalytic protocol for the isomerization of 1,2-disubstituted cyclopropanols to linear ketones. The reaction proceeds <i>via</i> radical intermediates and tolerates various functional groups.

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