- Synthesis of amphiphilic, chalcogen-based redox modulators with in vitro cytotoxic activity against cancer cells, macrophages and microbes
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Several amphiphilic, chalcogen-based redox modulators have been synthesized which exhibit a widespread, yet in some instances also selective, biological activity which is most likely based on their ability to modulate the intracellular redox balance and t
- Du, Peng,Viswanathan, Uma M.,Khairan, Khairan,Buric, Tomislav,Saidu, Nathaniel E. B.,Xu, Zhanjie,Hanf, Benjamin,Bazukyan, Inga,Trchounian, Armen,Hannemann, Frank,Bernhardt, Ingolf,Burkholz, Torsten,Diesel, Britta,Kiemer, Alexandra K.,Schaefer, Karl-Herbert,Montenarh, Mathias,Kirsch, Gilbert,Jacob, Claus
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- Free Radical Macrocyclisation via Propiolate Esters.
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Intramolecular free-radical addition to propiolate esters has provided a new and stereoselective route to 14-16 membered trans-α,β-unsaturated macrocyclic lactones from their corresponding ω-iodoalkyl-propiolate esters under triphenyltin hydride/AIBN mediated conditions.Attempts to synthesise analogous 10-13 membered lactones proved unsuccessful, resulting in acyclic products derived from direct reduction at the radical centre. Key words: Radical; macrocyclisation; propiolate ester; macrocyclic unsaturated lactone; high dilutionm
- Baldwin, Jack E.,Adlington, Robert M.,Ramcharitar, Steve H.
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p. 3413 - 3428
(2007/10/02)
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- Intramolecular SH2 macrocyclisations
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The synthesis of 10-15 membered α-methylene macrocyclic lactones from the functionalised allylstannanes (7e)-(7j) is described. Attempts to synthesise analogous 6-9 membered lactones proved unsuccessful, resulting instead in the production of dilactones and AIBN derived adducts.
- Baldwin, Jack E.,Adlington, Robert M.,Mitchell, Mark B.,Robertson, Jeremy
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p. 5901 - 5918
(2007/10/02)
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- Radical Reactions in Synthesis: Intramolecular SH2' Macrocyclisations
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The synthesis of 10-15 membered α-methylene lactones 1 from the functionalised allyl stannanes 2 occurs cleanly in moderate to high yield under free radical conditions via an intramolecular SH2' reaction.
- Baldwin, Jack E.,Adlington, Robert M.,Mitchell, Mark B.,Robertson, Jeremy
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p. 1574 - 1575
(2007/10/02)
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- Study of the reductive Cleavage of Selenides with Nickel Boride. A Convenient Deselenization Procedure
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The reductive deselenization of a variety of organoselenium compounds can be performed rapidly, conveniently, and in high yield by using nickel boride.The latter reagent was generated in situ by adding sodium borohydride to nickel chloride hexahydrate and the substrate selenide in THF-methanol at 0 deg C.Under these conditions, ca. 3-3.5 mol of borohydride was required to reduce all of the nickel salt to nickel boride and an excess of nickel boride was generally required to effect complete deselenization.Preformed nickel boride lost virtually all of its ability to cleave n-dodecyl phenyl selenide (2) after only 5 min, but continued to catalyze the decomposition of sodium borohydride.Deselenizing ability was not restored by the addition of hydrogen or further sodium borohydride to preformed nickel boride.Deuterium-labeling studies indicated that the hydrogen required for reductive deselenization originates from both the borohydride and the methanol solvent in a ratio of ca. 3:1.The use of sodium borodeuteride in methanol-d afforded 1-deuteriododecane of high isotopic purity, indicating that the procedure comprises a convenient method for preparing deuteriated products.The mechanism of nickel boride deselenization may involve transient nickel hydride or Ni(0) intermediates.The chemoselectivity of the reaction permits the cleavage of C-Se bonds in the presence of chlorides, nitriles, esters, sulfides, sulfones, ketones, and some olefins, but iodides and sulfinate esters undergo concomitant or preferential reduction.Electrochemical deselenization of 2 was studied and resulted in anodic oxidation of the selenide to 1-dodecene instead of cathodic reduction to n-dodecane.
- Back, Thomas G.,Birss, Viola I.,Edwards, Mark,Krishna, M. Vijaya
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p. 3815 - 3822
(2007/10/02)
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