Diastereoselective assembly of dispiro-cyclopentene-linked bisoxindoles via annulation involving isatylidene malononitriles and benzylamines

A cascade reaction utilizing benzylamines and two equivalents of isatylidene malononitriles in alcohols effectively produces dispiro[indoline-cyclopentapyrimidine-indoline] structures with high chemical yields, reaching up to 93%, and remarkable diastereoselectivity (dr ≥ 19 : 1). This one-pot synthesis, facilitated by nucleophilic solvent participation, provides a practical method for obtaining multicyclic dispiro-cyclopentene-linked bisoxindoles, generating four chiral centers in a diastereoselective fashion. The practical applicability of this approach was further illustrated through a gram-scale experiment, and the final product's structure was confirmed via single-crystal X-ray analysis, affirming the successful synthesis of the target compounds.