Brunner, Henri and Blüchel, Christian and Doyle, Michael P. (1997) Asymmetric catalysis .108. Copper catalysts with optically active ligands in the enantioselective Meerwein arylation of activated olefins. JOURNAL OF ORGANOMETALLIC CHEMISTRY, 541 (1-2). pp. 89-95. ISSN 0022-328X, 1872-8561
Full text not available from this repository.Abstract
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 alpha-chloro-beta-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 degrees 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. (C) 1997 Elsevier Science S.A.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | HALIDE DEAMINATION REACTIONS; TRANSFER OXIDATION; ALKYL RADICALS; HYDROSILYLATION; NITRITE; SALTS; Meerwein arylation; copper catalysts; enantioselectivity; optically active ligands; pyridinyloxazoline; bisoxazoline |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Prof. Dr. Henri Brunner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 30 Mar 2023 09:47 |
| Last Modified: | 30 Mar 2023 09:47 |
| URI: | https://pred.uni-regensburg.de/id/eprint/50649 |
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