Organocatalytic diastereo- and enantioselective 1,3-dipolar cycloaddition of azlactones and methyleneindolinones

Abstract

A simple route to complexity: An organocatalytic 1,3-dipolar cycloaddition between azlactones and methyleneindolinones provided spirooxindoles with high enantioselectivity (see scheme). This transformation takes advantage of the nucleophilic C4 and electrophilic C2 atoms in the azlactone substrate. Bn=benzyl, HOBt=1-hydroxy-1H-benzotriazole, MTBE=methyl tert-butyl ether, PG=protecting group, TMS=trimethylsilyl. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.