Abstract

Ultrasound irradiation in presence of 20 ZnBr2 effectively promotes regio- and stereo-selective cycloaddition reaction of azomethine ylide with a series of (E)-3-benzylideneindolin-2-ones to afford 3,3'-dispiropyrrolidine bisoxindole derivatives in excellent yields in methanol at room temperature. The factors affecting the cycloaddition reaction, for example solvent, catalyst, ultrasonic irradiation, are examined in detail to find the mildest conditions and highest reaction yields. The structure and stereochemistry of cycloadducts were determined by spectroscopic data and confirmed by X-ray crystallographic analysis.