Studies towards the construction of quaternary indolizidines by [2,3]-sigmatropic rearrangement cocatalyzed by ionic liquid

An efficient enantioselective approach for preparation of quaternary centers from proline 5 building block has been developed through [2,3]-sigmatropic Stevens rearrangement co-catalyzed by ionic liquid. The sigmatropic rearrangement was stereospecific because the [2,3]-migrations were restricted to the same face, and the stereoselectivity arose from the previous N-alkylation step in 8. The approach showed better yields than described in literature. The use of 1-butyl-3-methylimidazolium hexafluorophosphate showed an improvement in the yields of the Stevens rearrangement due to a possible stabilization and/or activatation of zwiterionicspecies in solution by the ionic liquid. Several indolizidine moieties were synthesized from quaternary proline derivative (S)-5.

Bibliographic Details

Main Authors:	Duran-Lara,Esteban F., Shankaraiah,Nagula, Geraldo,Daniela, Santos,Leonardo S.
Format:	Digital revista
Language:	English
Published:	Sociedade Brasileira de Química 2009
Online Access:	http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532009000500002
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