Please use this identifier to cite or link to this item: http://dx.doi.org/10.18419/opus-6984
Authors: Laschat, Sabine
Grehl, Matthias
Title: 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
Issue Date: 1994
metadata.ubs.publikation.typ: Zeitschriftenartikel
metadata.ubs.publikation.source: 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
Abstract: 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.
Appears in Collections:15 Fakultätsübergreifend / Sonstige Einrichtung

Files in This Item:
File Description SizeFormat 
las11.pdf1,28 MBAdobe PDFView/Open


Items in OPUS are protected by copyright, with all rights reserved, unless otherwise indicated.