120933-27-9Relevant articles and documents
Catalytic phosphorus(V)-mediated nucleophilic substitution reactions: Development of a catalytic appel reaction
Denton, Ross M.,An, Jie,Adeniran, Beatrice,Blake, Alexander J.,Lewis, William,Poulton, Andrew M.
experimental part, p. 6749 - 6767 (2011/10/02)
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.
Kinetic study on denomination of vic-dibromides with trivalent phosphorus compounds
Yasui, Shinro
, p. 217 - 222 (2007/10/03)
Various types of trivalent phosphorus compounds (I) brought about reductive debromination of vic-dibromides (2) to afford olefins. The reaction was accelerated by either electron-releasing substituents on the phosphorus of 1 or electron-with-drawing substituants on the α-carbon of 2. The substituent effects, along with the stereochemistry of the reaction, are consistent with an E1CB-like mechanism for the elimination of the two bromine atoms. That is, 1 initially undergoes nucleophilic attack upon a bromine of 2. At the transition state, a fractional positive charge is developed on the phosphorus of 1 and a fractional negative charge on the carbon of 2. This mechanism suggests the importance of an electronic character of the vic-dibromide in determining the relative ease of bromophilicity, carbophilicity, and basicity of the phosphorus of a trivalent phosphorus compound in a reaction with the dibromide. α 2001 John Wiley & Sons, Inc.
