Synthesis of Highly Enantioenriched Bis‐spirooxindole Pyrrolizidine/Pyrrolidines through Asymmetric [3+2] Cycloaddition Reaction

Synthesis of highly enantioenriched bis‐spirooxindole pyrrolizidine scaffold was established using 1,3‐dipolar cycloaddition of isatin‐derived azomethine ylides by (E)‐2‐oxoindolin‐3‐ylidene acetyl sultam with four contiguous and two quaternary stereogenic centers in generally high yields (up to 96%) and diastereoselectivities (up to 99 : 1). In addition, highly enantioenriched bis‐spirooxindole pyrrolidines were generated in high yields and highly regio‐ and ‐diastereoselectivities (up to 99 : 1) by utilizing this chiral auxiliary controlled method. The obtained cycloadducts underwent retro‐Mannich ring‐opening cyclization and produced new diastereoisomers of bis‐spirooxindole pyrrolizidine/pyrrolidines skeleton that could not be accessed by direct 1,3‐dipolar cycloaddition.