Synthesis of Enantioenriched 3-Amino-3-Substituted Oxindoles by Stereoselective Mannich Reaction Catalyzed by Supported Bifunctional Thioureas.

Enantioenriched 3-amino-3-substituted oxindoles have been obtained by addition of different nucleophiles to N-Boc ketimines derived from isatin catalyzed by chiral bifunctional supported thioureas. The Mannich reaction occurs with excellent enantioselection, but poor diastereoselection when prochiral nucleophiles were used. The supported catalyst were recovered and reused for five times without loss of activity. The mixture of diastereoisomers formed when a prochiral structure was used as nucleophile was converted into a single enantioenriched pyrazolyl derivative.