- Catalytic phosphorus(V)-mediated nucleophilic substitution reactions: Development of a catalytic appel reaction
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Catalytic phosphorus(V)-mediated chlorination and bromination reactions of alcohols have been developed. The new reactions constitute a catalytic version of the classical Appel halogenation reaction. In these new reactions oxalyl chloride is used as a consumable stoichiometric reagent to generate the halophosphonium salts responsible for halogenation from catalytic phosphine oxides. Thus, phosphine oxides have been transformed from stoichiometric waste products into catalysts and a new concept for catalytic phosphorus-based activation and nucleophilic substitution of alcohols has been validated. The present study has focused on a full exploration of the scope and limitations of phosphine oxide catalyzed chlorination reactions as well as the development of the analogous bromination reactions. Further mechanistic studies, including density functional theory calculations on proposed intermediates of the catalytic cycle, are consistent with a catalytic cycle involving halo- and alkoxyphosphonium salts as intermediates.
- Denton, Ross M.,An, Jie,Adeniran, Beatrice,Blake, Alexander J.,Lewis, William,Poulton, Andrew M.
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experimental part
p. 6749 - 6767
(2011/10/02)
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- Ionic liquids as reagents and solvents in conjunction with microwave heating: Rapid synthesis of alkyl halides from alcohols and nitriles from aryl halides
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We show that using ionic liquids as reagents in conjunction with microwave heating it is possible to prepare primary alkyl halides from the corresponding alcohols rapidly. Using ionic liquids as solvents in conjunction with microwave heating it is possible to prepare aryl nitriles from the corresponding aryl bromides or iodides. The scope and limitations of using microwave-promotion as a tool in these reactions is discussed.
- Leadbeater, Nicholas E.,Torenius, Hanna M.,Tye, Heather
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p. 2253 - 2258
(2007/10/03)
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- A safe and efficient procedure to prepare alkyl and alkoxyalkyl chlorides and dichlorides by catalytic decomposition of the corresponding alkyl and alkoxyalkyl chloroformates and bischloroformates with hexabutylguanidinium chloride
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Small amounts of hexabutylguanidinium chloride (0.01 mol%) decomposes pure chloroformates or bischloroformates with different lengths of carbon chains by a semicontinuous process to diminish run-away risk, leading to chloride compounds with high yield and purity.
- Violleau,Thiebaud,Borredon,Le Gars
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p. 367 - 373
(2007/10/03)
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- Novel Fused Bicyclic Sulphur Compounds
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Novel fused (cis-octahydrothienothiepine, cis-hexahydrothieno-1,4-oxathiine and cis-hexahydrothieno-1,4-dithiine) and spiro (1,4,6-trithiaspirononane and 1,4,7-trithiaspirononane) bicyclic compounds containing sulphur have been synthesized and their structures confirmed by NMR spectroscopy.For their synthesis, reactions of nucleophiles, including Grignard reagents, with trans-2,3-dichlorotetrahydrothiophene were investigated.Improved methods of forming sulphides from Na2S and haloalkanes have been developed. 1-Bromo-4-chlorobutane was shown to form the specific Grignard reagent, Cl4MgBr.
- Delaney, Paul A.,Johnstone, Robert A. W.,Leonard, Paul A.,Regan, Peter
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p. 285 - 289
(2007/10/02)
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In dimethylformamide or N-methylpyrrolidone the Ni-bipyridyl system catalyses the electrochemical reduction of functionalised or non-functionalised aliphatic halides. High yields of dimeric products are obtained besides primary mono- or di-bromides. Analysis of the reaction products shows the formation of dialkylnickel which can be isolated by coulometry. This species acts as a reducing agent for aliphatic halides.
- Mabrouk, Salah,Pellegrini, Sylvain,Folest, Jean-Claude,Rollin, Yolande,Perichon, Jacques
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p. 391 - 400
(2007/10/02)
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