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Influence of HMPA on the stereochemical outcome of the addition of a racemic allenylzinc onto enantiopure N-tert-butanesulfinimines: stereoselective access to enantiopure cis-ethynylaziridines.
- Source :
-
Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2005 Sep 05; Vol. 11 (18), pp. 5269-78. - Publication Year :
- 2005
-
Abstract
- In the presence of 60 equivalents of HMPA, the condensation of the racemic allenylzinc derived from 1-chloro-3-trimethylsilylpropyne onto enantiopure non-alpha-branched N-tert-butanesulfinimines was proven to give access to the corresponding cis-ethynylaziridines as the major products. The good cis selectivity observed presumably resulted from a high kinetic resolution with the allenylzinc being partially configurationally labile with respect to the time scale defined by the rate of the reaction. Both single crystal X-ray analysis and semiempirical calculations conducted at the MM2 and AM1 levels of theory proved that the reaction certainly occurred through a preferred synclinal transition state in a supra- or antarafacial S(E)2' process. In all cases, chromatographic purification over silica gel allowed the cis-ethynyl-N-tert-butanesulfinylaziridines to be obtained as diastereo- and enantiomerically pure compounds (dr >98:2 and ee >99%).
Details
- Language :
- English
- ISSN :
- 0947-6539
- Volume :
- 11
- Issue :
- 18
- Database :
- MEDLINE
- Journal :
- Chemistry (Weinheim an der Bergstrasse, Germany)
- Publication Type :
- Academic Journal
- Accession number :
- 15997436
- Full Text :
- https://doi.org/10.1002/chem.200500268