Formation of spiropyrrolidines from isatin, secondary amins, and alkylidene dimedone

A catalyst-free synthesis of stable spiropyrrolidines from isatin, secondary amines, and alkylidene dimedone in MeCN in 75-95% yield is described. The antioxidant properties and antimicrobial abilities of the synthesized compounds are investigated. For this purpose, the radical scavenging activity of four derivatives was studied by radical trapping of diphenylpicrylhydrazine and ferric reduction power experiments. Disk diffusion test on Gram-positive and Gram-negative bacteria employed to investigate antibacterial activities of five derivatives.