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.