Organocatalytic stereocontrolled synthesis of 3,3'-pyrrolidinyl spirooxindoles by [3+2] annulation of isocyanoesters with methyleneindolinones.

A stereoselective [3+2] cycloaddition of isocyanoesters to methyleneindolinones catalyzed by a quinine-based thiourea-tertiary amine has been successfully developed. Just by tuning the protecting groups on substrates, a variety of optically enriched 3,3'-pyrrolidinyl spirooxindole diastereomers could be obtained in excellent enantioselectivities (up to 99% ee). This journal is © The Royal Society of Chemistry 2012