The Stabilization of Lithiated Organic Compounds by Water as a Ligand – Synthesis of a New Lithium–Imidazole Complex and Regioselective Reactions with Selected Electrophiles
✍ Scribed by Jens Atzrodt; Rainer Beckert; Michael Bräuer; Karsten Nordhoff; Ernst Anders; Helmar Görls
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 216 KB
- Volume
- 1998
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
The deprotonation of the 4H-imidazoles 1 by lithium hydride Alkylation, as well as acylation, of 2 leads to the exocyclic substituted derivatives 3 and 5. The NMR spectra of 3 and 5 yields the lithiated derivatives 2 which contain a stable delocalized anion. Surprisingly, the X-ray crystal structure and the semiempirical calculations suggest the existence of two rotamers due to the low rotation barrier of the exocyclic analysis of 2a reveals one molecule of water in the first complexation sphere of the lithium cation. This result is in C-N bond. Another type of acylation is observed when phenylacetyl chloride is used as an acylating agent. The X-good agreement with semiempirical calculations (PM3) which predict an increase in stability on substitution of ether ray crystal structure analysis of 6c reveals that a rearrangement forming an unsaturated acid amide ligands by water molecules. The deprotonation of 1 is accompanied by a change of colour from orange to purple substructure takes place. because of the polymethinic character of the resulting anion.