Ultrasonic assisted-silica mediated [3+2] cycloaddition of azomethine ylides—a facile multicomponent one-pot synthesis of novel dispiroheterocycles

An efficient synthesis of dispiro-oxindolopyrrolizidine and dispirooxindolothienopyrrole derivatives has been expediently accomplished via a one-pot, three-component 1,3-dipolar cycloaddition reaction. High regioselectivity was achieved on ultrasonication in the presence of silica as a catalyst. X-ray diffraction studies of one of the cycloadducts proved the structure and regiochemistry of the cycloaddition.