3909-19-1Relevant articles and documents
Arenediazonium tetrachlorocuprates(II). Modified versions of the Meerwein and Sandmeyer reactions
Obushak,Lyakhovich,Bilaya
, p. 38 - 46 (2007/10/03)
Chloroarylation of unsaturated compounds with arenediazonium chlorides in the presence of CuCl2 as catalyst involves intermediate formation of arenediazonium tetrachlorocuprates(II) [ArN2+] 2 CuCl4su
Arenediazonium tetrachlorocuprates(ii). Modification of the meerwein and sandmeyer reactions
Obushak, Mykola D.,Lyakhovych, Mykhaylo B.,Ganushchak, Mykola I.
, p. 9567 - 9570 (2007/10/03)
In the copper-catalysed reactions of arenediazonium chlorides with unsaturated compounds arenediazonium tetrachlorocuprates(II) are formed as intermediates. A general method of preparation of these complexed diazonium salts is described. In polar solvents these salts undergo chlorinative dediazoniation to give chloroarenes in high yield. The reaction of an arenediazonium tetrachlorocuprate(II) with an activated alkene results in the same products as the Meerwein reaction. A radical cation mechanism for this reaction is proposed.
Asymmetric catalysis, part 108: Copper catalysts with optically active ligands in the enantioselective Meerwein arylation of activated olefins
Brunner, Henri,Bluechel, Christian,Doyle, Michael P.
, p. 89 - 95 (2007/10/03)
The copper-catalyzed Meerwein reaction of activated olefins with arenediazonium halides leads to a formal addition of aryl halide to the olefinic double bond. Methyl acrylate, p-tolyldiazonium tetrafluoroborate and tetrabutylammonium chloride in anhydrous acetonitrile were used as a model system, the product being methyl a-chloro-β-tolylpropionate. Applying a newly established methodology, the isolated diazonium tetrafluoroborate and an equivalent amount of tetrabutylammonium chloride were added to the olefin and the copper catalyst, containing optically active ligands, such as 2-and 2,6-pyridinyloxazolines and bisoxazolines. The low optical inductions obtained in the room temperature reaction could be raised to 8.7% ee in the low temperature variant at -40 °C. Two phenyl substituents in the neighborhood of the chiral centers in the bisoxazoline ligands of the catalyst and increasing steric bulk in the ester group of the substrate (methyl, ethyl, menthyl) increase the stereoselectivity of the Meerwein arylation. Replacement of the p-tolyldiazonium salt by the mesityldiazonium salt caused the optical induction in the formation of the corresponding mesityl product rise to 19.5% ee. Thus, though considered to be a radical reaction, the Meerwein arylation of activated olefins can be rendered enantioselective by using copper catalysts with optically active ligands.
