α-Lithiated (R,R)-TMCDA as an Efficient Building Block for the Preparation of Chiral N,N,O Ligands by Asymmetric 1,2-Addition
✍ Scribed by Viktoria H. Gessner; Benjamin Fröhlich; Carsten Strohmann
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 522 KB
- Volume
- 2010
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
The chiral diamine (1__R__,2__R__)‐N,N,N′,N′‐tetramethylcyclohexane‐1,2‐diamine [(R,R)‐TMCDA, 3] has been selectively deprotonated at one of its methyl groups by a series of alkyllithium bases. Although the enantiomerically pure compound formed a trimeric structure, direct lithiation of the racemic mixture of the amine (trans‐TMCDA) yielded a tetrameric compound. With 2 equiv. of the deprotonation reagent a mixed aggregate of the lithiated amine and tert‐butyllithium was formed. The lithiated amine was employed as a building block for the synthesis of novel nitrogen ligands. The asymmetric 1,2‐addition of α‐lithiated (R,R)‐TMCDA onto different ketones and aldehydes yielded a series of novel N,N,O ligands with different substitution patterns. Depending on the carbonyl compound used, a new stereocentre and different substituents can be introduced. The coordination behaviour of these ligands is illustrated by the formation of metal salt complexes.