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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Mansueto, Rosmara Rizzi, Rosanna Degennaro, Leonardo Pratt, Lawrence M. Carenza, Elisa Florio, Saverio Luisi, Renzo |
| Description | Author Affiliation: Degennaro L ( Dipartimento Farmaco-Chimico, University of Bari, Aldo Moro, Via E. Orabona 4, 70125-Bari, Italy.) |
| Abstract | Diastereomeric oxazolinylaziridines (R,R)-9 and (R,S)-9 have been regioselectively lithiated at the α-position with respect to the oxazolinyl ring. The resulting aziridinyllithium compounds proved to be chemically and configurationally stable under the experimental conditions used, thus furnishing, upon trapping with electrophiles, chiral 2,2-disubstituted aziridines, in contrast to the corresponding α-lithiated oxazolinyloxiranes that have been reported to be chemically stable but configurationally unstable. This peculiar behavior of the nitrogen-bearing heterocycle has been rationalized on the basis of DFT calculations and the observed dynamics of the aziridine nitrogen atom. The DFT analysis allowed the disclosure of a solvent-dependent differing stability of diastereomeric lithiated aziridines (R,R)-9-Li and (R,S)-9-Li, suggesting $η^{3}-coordinated$ oxazolinylaziridinyllithium compounds as likely intermediates. Such intermediates could be the result of a dynamically controlled lithiation that relies on the preliminary formation of a complex between the lithiating agent and the oxazolinyl ring. According to this model, the competing complexation of the lithiating agent by the lone pair of electrons on the aziridine nitrogen would cause addition to the oxazoline CN bond, thus ending up with the formation of oxazolidines, which are precursors of useful chiral ketoaziridines. The proposed model has been also supported by estimating the nitrogen inversion barrier by dynamic NMR spectroscopic experiments. |
| ISSN | 09476539 |
| e-ISSN | 15213765 |
| Journal | Chemistry - A European Journal |
| Issue Number | 18 |
| Volume Number | 17 |
| Language | English |
| Publisher | Wiley-VCH;ChemPubSoc Europe |
| Publisher Date | 2011-04-26 |
| Publisher Place | Germany |
| Access Restriction | Open |
| Subject Keyword | Aziridines Chemical Synthesis Lithium Chemistry Nitrogen Organometallic Compounds Oxazoles Magnetic Resonance Spectroscopy Models, Molecular Molecular Structure Stereoisomerism Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. |
| Content Type | Text |
| Resource Type | Article |
| Subject | Organic Chemistry Catalysis |
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