In this study, we developed a novel methodology involving a base-controlled, rongalite-mediated reductive/aldol reaction, followed by cyclization of isatylidene malononitriles/cyanoacetates, resulting in the synthesis of spiro[2,3-dihydrofuran-3,3 `-oxindole]. Additionally, we have disclosed a rongalite-mediated dimerization process for isatylidene malononitriles, yielding dispiro[cyclopent-3 `-ene]bisoxindole. The utilization of rongalite in this reaction serves a dual purpose, acting both as a reducing agent and a C1 synthon. The developed approach has several advantages like a simple reaction setup, a wide substrate scope, requiring less time, using water as a green solvent, no metal or catalyst is required and products can be easily isolated via filtration with excellent yields under mild reaction conditions. A novel methodology was developed for the synthesis of spiro[2,3-dihydrofuran-3,3 `-oxindole] and dispiro[cyclopent-3 `-ene]bisoxindole under mild reaction conditions using inexpensive reagents.

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