1. Anion-Binding Catalysis by Electron-Deficient Pyridinium Cations.
- Author
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Berkessel, Albrecht, Das, Somnath, Pekel, Daniel, and Neudörfl, Jörg‐M.
- Subjects
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ANIONS , *ELECTRON-deficient compounds , *ELECTRON-deuteron interactions , *PYRIDINIUM compounds , *CATIONS , *ELECTROPHILES - Abstract
A new activation principle in organocatalysis is presented: halide binding through Coulombic interactions. This mode of catalysis was realized by using 3,5-di(carbomethoxy) pyridinium ions that carry an additional electronwithdrawing substituent on the nitrogen atom, for example, pentafluorobenzyl or cyanomethyl. For the N-pentafluorobenzyl derivative, Coulombic interaction with the pyridinium moiety is complemented in the solid state by anion-Π interactions with the perfluorophenyl ring. Bromide and chloride are bound by these cations in a 1:1 stoichiometry. Catalysis of the C-C coupling between 1-chloroisochroman (and related electrophiles) with silyl ketene acetals occurs at -78°C and at low catalyst loading (2 mol%). [ABSTRACT FROM AUTHOR]
- Published
- 2014
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