SciELO - Scientific Electronic Library Online

 
vol.20 issue5Synthesis, characterization and kinetics of catalytically active molecularly imprinted polymers for the selective recognition of 4-aminophenol author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Journal of the Brazilian Chemical Society

Print version ISSN 0103-5053

Abstract

DURAN-LARA, Esteban F.; SHANKARAIAH, Nagula; GERALDO, Daniela  and  SANTOS, Leonardo S.. Studies towards the construction of quaternary indolizidines by [2,3]-sigmatropic rearrangement cocatalyzed by ionic liquid. J. Braz. Chem. Soc. [online]. 2009, vol.20, n.5, pp. 813-819. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50532009000500002.

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.

Keywords : Stevens rearrangement; [2,3]-sigmatropic; indolizidines; ionic liquid; co-catalyzed.

        · abstract in Portuguese     · text in English     · pdf in English