Bitte benutzen Sie diese Kennung, um auf die Ressource zu verweisen:
http://dx.doi.org/10.18419/opus-6984
Autor(en): | Laschat, Sabine Grehl, Matthias |
Titel: | Diastereoselective synthesis of α-Hydroxy- and α-amino-indolizidines and -quinolizidines : evidence for a novel cyclization/hydride migration mechanism in the TiCl4-induced reaction of prolinalbenzylimines by deuterium labeling studies |
Erscheinungsdatum: | 1994 |
Dokumentart: | Zeitschriftenartikel |
Erschienen in: | Chemische Berichte 127 (1994), S. 2023-2034. URL http://dx.doi.org./10.1002/cber.19941271027 |
URI: | http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-41663 http://elib.uni-stuttgart.de/handle/11682/7001 http://dx.doi.org/10.18419/opus-6984 |
Zusammenfassung: | Lewis acid-catalyzed cyclization of prolinal and 2-piperidine-carbaldehyde benzylimines 11, 12 results in the diastereoselective formation of α-amino-β-alkyl-substituted indolizidines 15, 17, 19, 21 and -quinolizidines 16, 18, 20, respectively. Both diastereoselectivity and constitution depend on the Lewis acid. FeCl3 yields α,β- trans-α-(benzylamino)-β-isopropenyl derivatives 15 and 16, probably by a cationic cyclization via carbenium ions 32a, b. In contrast, TiCl4 yields ,α,β- cis-α-(benzylideneamino)-β-isopropyl derivatives 19 and 20 by a novel cyclization/intermolecular hydride transfer mechanism, which was supported by deuterium labeling studies. Compounds 15, 16, 19, and 20 were converted to the diastereomeric acetamides 24, 25 and 28, 29. By an analogous cyclization of the aldehydes 8 and 9 only α ,β-cis-α-hydroxy--isopropenylindolizidines 51 and -quinolizidines 52 were obtained irrespective of the Lewis acid used. The structures of 30 and 52 were elucidated by X-ray analysis. |
Enthalten in den Sammlungen: | 15 Fakultätsübergreifend / Sonstige Einrichtung |
Dateien zu dieser Ressource:
Datei | Beschreibung | Größe | Format | |
---|---|---|---|---|
las11.pdf | 1,28 MB | Adobe PDF | Öffnen/Anzeigen |
Alle Ressourcen in diesem Repositorium sind urheberrechtlich geschützt.