Azomethine ylide [3+2]-cycloaddition of 3-alkylidene-7-aza-2-indolone: Synthesis of 3,3'-dispiropyrrolidine- and 3,3'-dispiropyrrolizidine bis 7-aza-2-oxindoles

32 AY CA reactions of 3-alkylidene-7-aza-2-indalone with acyclic and cyclic AY's generated in situ from 7-azaisatin/isatin and sarcosine/proline in the presence of Montmorillonite k10 clay afforded highly func-tionalized 3, 3'-dispiropyrrolidine-and 3,3'-dispiropyrrolizidine bis 7-aza and 2-oxindole in excellent yield. The structure of the representative cycloadducts was established by single-crystal XRD. A plausible reaction mechanism is provided. Significantly the final product forms with newly formed two quaternary spiro carbons and two stereogenic centers simultaneously.(c) 2023 Elsevier Ltd. All rights reserved.