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Highly Enantioselective Reactions of Configurationally Labile Epimeric Diamine Complexes of Lithiated S‐Benzyl Thiocarbamates |
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| Authors: | Heiko Lange Klaus Bergander Dr. Roland Fröhlich Dr. Seda Kehr Dr. Shuichi Nakamura Prof. Dr. Norio Shibata Prof. Dr. Takeshi Toru Prof. Dr. Dieter Hoppe Prof. Dr. |
| Affiliation: | 1. Organisch‐Chemisches Institut der Universit?t, Westpf?lische Wilhelms‐Universit?t Münster, Corrensstr. 40, 48149 Münster, Germany, Fax: (+49)?251 83 33265;2. Department of Applied Chemistry, Nagoya Institute of Technology, Gokiso, Showa‐ku, Nagoya 466‐8555, Japan, Fax: (+81)?52 735 5217 |
| Abstract: | Substitution reactions that employ primary‐carbamoyl‐protected arylmethanethiols are described. The enantiodetermining step was found to occur in the post‐deprotonation step as a dynamic thermodynamic resolution with a chiral bis(oxazoline) ligand. The configurationally labile lithium complexes were trapped with various electrophiles to yield different substitution products in good to excellent yields and enantiomeric excesses. The absolute configurations of the substitution products were determined, and the stereochemical pathway of the substitution reaction was elucidated for different classes of electrophiles. The temperature‐dependent epimerization process was monitored by 1H and 6Li NMR spectroscopy. |
| Keywords: | asymmetric synthesis bis(oxazoline) ligands carbanions dynamic thermodynamic resolution lithium |