%0 Journal Article
%T Studies towards the construction of quaternary indolizidines by [2,3]-sigmatropic rearrangement cocatalyzed by ionic liquid
%A Duran-Lara
%A Esteban F.
%A Shankaraiah
%A Nagula
%A Geraldo
%A Daniela
%A Santos
%A Leonardo S.
%J Journal of the Brazilian Chemical Society
%D 2009
%I Sociedade Brasileira de Qu¨Şmica, SBQ
%R 10.1590/S0103-50532009000500002
%X 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.
%K stevens rearrangement
%K [2
%K 3]-sigmatropic
%K indolizidines
%K ionic liquid
%K co-catalyzed.
%U http://www.scielo.br/scielo.php?script=sci_abstract&pid=S0103-50532009000500002&lng=en&nrm=iso&tlng=en