Evaluation of thiocarbonyl and thioester moieties as thiol protecting groups for controlled radical polymerization

Neindre, Morgane Le; Magny, Benoît; Nicolaÿ, Renaud

doi:10.1039/c3py00754e

Cited by 42 publications

(45 citation statements)

References 34 publications

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“…We thus had to use a more complicated procedure for the fixation of trithiocarbonate moieties. The xanthate moiety also undergoes aminolysis, just like trithiocarbonate groups; therefore, the use of NH 3 should be avoided in the presence of xanthate moieties. In this study, to introduce a suitable SI‐MADIX chain‐transfer agent on the SiP surface, we adopted another approach in which alkyl bromide groups fixed on the particle surface were converted to xanthate moieties.…”

Section: Resultsmentioning

confidence: 99%

Grafting of Polymer Brushes from Xanthate‐Functionalized Silica Particles

Ohno

Yahata

Sakaue

et al. 2019

Chemistry A European J

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Monodisperse silica particles (SiPs) were surface‐modified with a newly designed silane coupling agent comprising a triethoxysilane and an alkyl halide, namely, 6‐(triethoxysilyl)hexyl 2‐bromopropionate, which was further treated with potassium O‐ethyl dithiocarbonate (PEX) to immobilize xanthate molecules on the particle surfaces. Surface‐initiated macromolecular design via interchange of xanthates (MADIX) polymerization of vinyl acetate (VAc) was conducted with the xanthate‐functionalized SiPs. The polymerization was well controlled and produced SiPs coated with poly(vinyl acetate) (PVAc) with a well‐defined target molar mass and a graft density of about 0.2 chains nm−2. Dynamic light scattering and TEM measurements revealed that the hybrid particles were highly dispersible in good solvents without any aggregation. The PVAc brushes were hydrolyzed with hydrochloric acid to produce poly(vinyl alcohol) brushes on the SiP surfaces. In addition, the number of xanthate molecules introduced on the SiP surfaces could be successfully controlled by adjusting the concentration of PEX. Thus, the SiPs have two functionalities: xanthates able to act as a MADIX chain‐transfer agent and alkyl bromide initiation sites for atom transfer radical polymerization (ATRP). By using these unique bifunctional particles, mixed polymer brushes were constructed on the SiPs by MADIX of VAc followed by ATRP of styrene or methyl methacrylate.

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Section: Resultsmentioning

confidence: 99%

Grafting of Polymer Brushes from Xanthate‐Functionalized Silica Particles

Ohno

Yahata

Sakaue

et al. 2019

Chemistry A European J

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“…[8,9] We thus considered a less electrophilic dithiocarbonyl derivative–a dithiocarbamate–as the transfer group for our studies. Notably, the dithiocarbamate group is also a useful pharmacophore with roles in enzyme catalysis, protein folding, and redox signaling and regulation.…”

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confidence: 99%

A General Approach to Site‐Specific, Intramolecular C−H Functionalization Using Dithiocarbamates

Alexanian

2018

Angew Chem Int Ed

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Intramolecular hydrogen-atom transfer is an established approach for the site-specific functionalization of unactivated, aliphatic C–H bonds. Transformations using this strategy typically require unstable intermediates formed using strong oxidants and have mainly targeted C–H halogenations or intramolecular aminations. Herein, we report a site-specific C–H functionalization that significantly increases the synthetic scope and convergency of reactions proceeding via intramolecular hydrogen atom transfer. Stable, isolable N-dithiocarbamates are used as precursors to amidyl radicals formed via either light or radical initiation to efficiently deliver highly versatile alkyl dithiocarbamates across a wide range of complex structures.

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“…44, 45 As illustrated in Scheme 2, S-2-hydroxyethyl-O-ethyl dithiocarbonate 5 was first synthesized by adding 2-bromoethanol (26 g) in acetone (80 mL) dropwise over 1 h to a 500-mL roundbottom containing potassium ethyl xanthogenate (40 g) in acetone (200 mL). The reaction was stirred, covered, at room temperature overnight.…”

Section: Methodsmentioning

confidence: 99%

Multivalent Presentation of Peptide Targeting Groups Alters Polymer Biodistribution to Target Tissues

et al. 2017

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Drug delivery to bone is challenging, whereby drug distribution is commonly <1% of injected dose, despite development of several bone-targeted drug delivery systems specific to hydroxyapatite. These bone-targeted drug delivery systems still suffer from poor target cell localization within bone, as at any given time overall bone volume is far greater than acutely remodeled bone volume, which harbors relevant cell targets (osteoclasts or osteoblasts). Thus, there exists a need to target bone-acting drugs specifically to the cells responsible for bone remodeling. To address this need, this study synthesized oligo(ethylene glycol) copolymers based on a peptide with high affinity to tartrate-resistant acid phosphatase (TRAP), an enzyme deposited by osteoclasts during the bone resorption phase of bone remodeling, which provides greater specificity relevant for bone cell drugging. Gradient and random peptide orientations, as well as polymer molecular weights, were investigated. TRAP-targeted, high molecular weight (Mn) random copolymers exhibited superior accumulation in remodeling bone, where fracture accumulation was observed for at least one week and accounted for 14% of tissue distribution. Intermediate and low Mn random copolymer accumulation was lower, indicating residence time depends on Mn. High Mn gradient polymers were cleared, with only 2% fracture accumulation after one week, suggesting TRAP binding depends on peptide density. Peptide density and Mn are easily modified in this versatile targeting platform, which can be applied to a range of bone drug delivery applications.

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Evaluation of thiocarbonyl and thioester moieties as thiol protecting groups for controlled radical polymerization

Cited by 42 publications

References 34 publications

Grafting of Polymer Brushes from Xanthate‐Functionalized Silica Particles

Grafting of Polymer Brushes from Xanthate‐Functionalized Silica Particles

A General Approach to Site‐Specific, Intramolecular C−H Functionalization Using Dithiocarbamates

Multivalent Presentation of Peptide Targeting Groups Alters Polymer Biodistribution to Target Tissues

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