The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mathew A Lucas - One of the best experts on this subject based on the ideXlab platform.
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design synthesis application and recovery of a minimally fluorous diaryl Diselenide for the catalysis of stannane mediated radical chain reactions
Tetrahedron, 1999Co-Authors: David Crich, Mathew A LucasAbstract:Abstract The synthesis of a minimally fluorous (52% F) diaryl Diselenide is described. On reduction in situ with tributylstannane this Diselenide provides a fluorous selenol which is effective in inhibiting a range of stannane-mediated radical rearrangements, including a cyclopropylcarbinyl ring opening. A method for the recovery of the fluorous Diselenide involving continuous extraction in a modified, cooled continuous extractor is described.
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inhibition of stannane mediated radical rearrangements by a recoverable minimally fluorous selenol
Organic Letters, 1999Co-Authors: David Crich, Mathew A LucasAbstract:The preparation of a minimally fluorous diaryl Diselenide is described. It is demonstrated that this Diselenide, reduced in situ to the corresponding selenol, may be used in conjunction with stannanes to prevent a number of radical rearrangements. A 1 M solution of this selenol used in admixture with Breslow's water-soluble stannane can be used to significantly inhibit a cyclopropylcarbinyl ring opening. The combination of the fluorous selenol and the polar stannane permits recovery of the selenol by continuous fluorous extraction and isolation of a stannane-free hydrocarbon product.
Michel Derock - One of the best experts on this subject based on the ideXlab platform.
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on the role of triethyl borate in the reduction of elemental selenium Diselenide dianions sodium decyl diselenolate and didecyl Diselenide with sodium borohydride
Synlett, 2005Co-Authors: Alain Krief, Michel DerockAbstract:Addition of triethyl borate to disodium Diselenide or to sodium decyl diselenolate allows their reduction with sodium borohydride which otherwise does not take place.
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condition driven selective syntheses of dialkyl Diselenides involving elemental selenium and sodium borohydride
Synlett, 2005Co-Authors: Alain Krief, Michel DerockAbstract:Dialkyl Diselenides have been prepared from alkyl halides, sodium borohydride and elemental selenium using two different methods. One of them involves the intermediate formation of Diselenide dianion equivalent ( - SeSe - ).
Filip Du Prez - One of the best experts on this subject based on the ideXlab platform.
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In Situ Cross-Linked Nanofibers by Aqueous Electrospinning of Selenol-Functionalized Poly(2-oxazoline)s
Macromolecules, 2018Co-Authors: Maarten Vergaelen, Xiangqiang Pan, Filip Du Prez, Richard Hoogenboom, Karen De ClerckAbstract:Poly(2-oxazoline)-based biomaterials have shown significant potential for various applications in the past decade. Herein, we present a methodology for the design of degradable Diselenide-cross-linked nanofibers by aqueous electrospinning of selenol (SeH)-modified poly(2-ethyl-2-oxazoline) (PEtOx). The selenol groups have been introduced into PEtOx by reacting partially hydrolyzed PEtOx (poly(2-ethyl-2-oxazoline-)-co-ethylenimine (PEtOx-EI)) with γ-butyroselenolactone, whereby ring-opening upon reaction with the secondary amine groups in the polymer backbone yields selenol side chains. Subsequent aqueous electrospinning of the selenol-containing PEtOx was found to lead to in situ cross-linked water-stable nanofibers, ascribed to the formation of Diselenide cross-links. The effects of changes in the experimental parameters and the influence of the selenium content on the electrospinning process were investigated in detail. Dynamic exchange between the remaining free SeH groups and Diselenide bonds formed u...
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In Situ Cross-Linked Nanofibers by Aqueous Electrospinning of Selenol-Functionalized Poly(2-oxazoline)s
2018Co-Authors: Maarten Vergaelen, Xiangqiang Pan, Filip Du Prez, Richard Hoogenboom, Karen De ClerckAbstract:Poly(2-oxazoline)-based biomaterials have shown significant potential for various applications in the past decade. Herein, we present a methodology for the design of degradable Diselenide-cross-linked nanofibers by aqueous electrospinning of selenol (SeH)-modified poly(2-ethyl-2-oxazoline) (PEtOx). The selenol groups have been introduced into PEtOx by reacting partially hydrolyzed PEtOx (poly(2-ethyl-2-oxazoline-)-co-ethylenimine (PEtOx-EI)) with γ-butyroselenolactone, whereby ring-opening upon reaction with the secondary amine groups in the polymer backbone yields selenol side chains. Subsequent aqueous electrospinning of the selenol-containing PEtOx was found to lead to in situ cross-linked water-stable nanofibers, ascribed to the formation of Diselenide cross-links. The effects of changes in the experimental parameters and the influence of the selenium content on the electrospinning process were investigated in detail. Dynamic exchange between the remaining free SeH groups and Diselenide bonds formed upon cross-linking enabled a tunable dissolution of the PEtOx-based nanofibers, which could be controlled by changing both the temperature and cross-linking density. Furthermore, the dissolution of the Diselenide cross-linked nanofibers could also be induced by the exchange of Diselenide groups under ultraviolet (UV) irradiation
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Selenolactone as a Building Block toward Dynamic Diselenide-Containing Polymer Architectures with Controllable Topology
ACS Macro Letters, 2017Co-Authors: Xiangqiang Pan, Frank Driessen, Xiulin Zhu, Filip Du PrezAbstract:A versatile protocol for the synthesis of a variety of multiresponsive Diselenide-containing polymeric architectures was investigated. It consists of a one-pot, two-step process with the generation of a selenol by in situ nucleophilic ring opening of selenolactone with a broad range of amine-containing structures, followed by the transformation of the obtained compounds to the corresponding Diselenide through a spontaneous oxidation coupling reaction. After elaboration of this one-pot reaction, a number of routes based on selenolactones have been developed for the successful synthesis of functional, linear, branched, cyclic, and cross-linked polymers via a mild, straightforward process. Moreover, the polymer end groups can be easily modified by changing the ratio of amine and selenolactone or sequential Michael addition of selenol to the methacrylic ester. At last, the self-healing properties of the Diselenide-containing networks were determined by exposing a cut sample of the polymer to UV light.
David Crich - One of the best experts on this subject based on the ideXlab platform.
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design synthesis application and recovery of a minimally fluorous diaryl Diselenide for the catalysis of stannane mediated radical chain reactions
Tetrahedron, 1999Co-Authors: David Crich, Mathew A LucasAbstract:Abstract The synthesis of a minimally fluorous (52% F) diaryl Diselenide is described. On reduction in situ with tributylstannane this Diselenide provides a fluorous selenol which is effective in inhibiting a range of stannane-mediated radical rearrangements, including a cyclopropylcarbinyl ring opening. A method for the recovery of the fluorous Diselenide involving continuous extraction in a modified, cooled continuous extractor is described.
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inhibition of stannane mediated radical rearrangements by a recoverable minimally fluorous selenol
Organic Letters, 1999Co-Authors: David Crich, Mathew A LucasAbstract:The preparation of a minimally fluorous diaryl Diselenide is described. It is demonstrated that this Diselenide, reduced in situ to the corresponding selenol, may be used in conjunction with stannanes to prevent a number of radical rearrangements. A 1 M solution of this selenol used in admixture with Breslow's water-soluble stannane can be used to significantly inhibit a cyclopropylcarbinyl ring opening. The combination of the fluorous selenol and the polar stannane permits recovery of the selenol by continuous fluorous extraction and isolation of a stannane-free hydrocarbon product.
Akiya Ogawa - One of the best experts on this subject based on the ideXlab platform.
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synthesis of selenium compounds by free radical addition based on visible light activated se se bond cleavage
Mini-reviews in Medicinal Chemistry, 2013Co-Authors: Akihiro Nomoto, Yohsuke Kobiki, Yoshihiro Higuchi, Akiya OgawaAbstract:Upon irradiation with near-UV or visible light, organic Diselenides undergo homolytic cleavage of their selenium-selenium linkage to generate the corresponding seleno radicals, which can add to alkynes, allenes, and related unsaturated compounds. In the case of alkynes, vicinally diselenated alkenes are synthesized successfully. Photoinduced bisselenation of allenes takes place selectively at the terminal double bond of allenes. In sharp contrast, photoinduced addition of organic Diselenides to alkenes is an inefficient process. However, combination of Diselenides and disulfides under photoirradiation conditions results in highly regioselective thioselenation of alkenes based on the higher reactivity of thio radicals toward alkenes and the higher carbon radical capturing ability of Diselenides. Similar conditions can be employed with a variety of unsaturated compounds such as alkynes, allenes, conjugated dienes, vinylcyclopropanes, and isocyanides. This protocol can also be applied to selenotelluration, selenophosphination, and perfluoroalkylselenation of unsaturated compounds. The excellent carbon radical capturing ability of Diselenides makes it possible to attain sequential addition of Diselenides to several unsaturated compounds by suppression of polymerization of unsaturated compounds. When the sequential addition takes place intramolecularly under photoirradiation conditions, cyclic products are obtained successfully via a radical cyclization process. In addition, novel photoinduced electrocyclic reaction of o-alkynylaryl isocyanides with Diselenides efficiently affords diselenated quinoline derivatives.
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diphenyl Diselenide as a useful reagent for intermolecular domino reactions of various unsaturated compounds under photoirradiation conditions
Bulletin of the Chemical Society of Japan, 2005Co-Authors: Kaname Tsuchii, Mikio Doi, Ikuko Ogawa, Yoshiyuki Einaga, Akiya OgawaAbstract:This paper describes full details of a series of intermolecular domino reactions mediated by diphenyl Diselenide (PhSeSePh). Diphenyl Diselenide, which has just the right strength of carbon radical capturing ability, can be employed as a useful mediator for intermolecular domino reactions of unsaturated compounds. Upon irradiation through Pyrex with a tungsten lamp (hv > 300 nm), a sequential addition of diphenyl Diselenide to alkynes bearing an electron-withdrawing group and alkenes bearing an electron-donating group proceeds successfully to provide the corresponding intermolecular three-component coupling products in high yields. In place of alkenes, the use of isocyanides leads to the formation of the corresponding three-component coupling products of alkynes, isocyanides, and (PhSe) 2 , selectively. Moreover, when two kinds of alkenes (i.e., electron-rich alkenes and electron-poor alkenes) are used in this photoinduced alkyne-(PhSe) 2 reaction system, a novel domino reaction of diphenyl Diselenide with an alkyne and two kinds of alkenes, followed by 5-exo radical cyclization, takes place sequentially to provide the corresponding cyclic four-component coupling products in good yields.
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Selective sequential addition of diphenyl Diselenide to ethyl propiolate and isocyanides upon irradiation with near-UV light
Tetrahedron Letters, 2001Co-Authors: Akiya Ogawa, Mikio Doi, Kaname Tsuchii, Toshikazu HiraoAbstract:Upon irradiation through Pyrex with a tungsten lamp (hν>300 nm), diphenyl Diselenide adds to electron-deficient alkynes such as ethyl propiolate and isocyanides sequentially to provide the corresponding three-component coupling products in moderate to high yields selectively. The appropriate strength of carbon-radical trapping by diphenyl Diselenide facilitates its selective three-component coupling with ethyl propiolate and isocyanides.