Synthesis of highly substituted spiropyrrolidines via 1,3-dipolar cycloaddition reaction of N-metalated azomethine ylides

3-Arylidene-4-chromanones undergo regioselective 1,3-dipolar cycloaddition reactions with N-metalated azomethine ylides derived from aromatic aldimines of glycine methyl ester in the presence of silver acetate and triethylamine to give spiropyrrolidine derivatives in good yield. X-Ray crystal structure analysis of one of the products confirms the structure and regiochemistry of the cycloadditions. (C) 2001 Elsevier Science Ltd. All rights reserved.