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α‐Lithiated ( R , R )‐TMCDA as an Efficient Building Block for the Preparation of Chiral N,N,O Ligands by Asymmetric 1,2‐Addition
Author(s) -
Gessner Viktoria H.,
Fröhlich Benjamin,
Strohmann Carsten
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201000631
Subject(s) - chemistry , deprotonation , diamine , reagent , amine gas treating , medicinal chemistry , enantioselective synthesis , stereochemistry , salt (chemistry) , organic chemistry , catalysis , ion
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.