Metal‐Free K2S2O8 Mediated Synthesis of 3‐(Substituted)‐2‐Arylisoindolin‐1‐one Derivatives With Cascade C‐N / C‐C Bond Formations Via Radical Cyclization

A facile technique was demonstrated for the synthesis of 2-hydroxy-2-[N-(alkyl/aryl/heteroaryl)-3-oxoisoindolin-1-yl]-1H-indene-1,3(2H)-diones by using a metal- free persulfate-mediated one pot three-component reaction. The reaction involved the combination effect of TBAB (PTC) and K2S2O8 with the addition of the amine to phthalaldehyde and 2,2-dihydroxyindane-1,3-dione to generate isoindolin-1-one in-situ, followed by cyclization.This lactamization process facilitated the formation of C–N bonds under controllable and ambient reaction conditions. A variety of 2-hydroxy-2-[N-(substituted)-3-oxoisoindolin-1-yl]-1H-indene-1,3(2H)-diones were successfully synthesized through a radical pathway from isoindolin-1-one, involving C-C bond formation. The method demonstrated high functional group compatibility and a wide substrate scope, resulting in moderate to good yields of the desired products. Additionally, the mechanistic analyses demonstrated that isoindolin-1-one  might be a significant intermediate being involved in the reaction. X-ray diffraction analysis was used to examine the crystal structures of synthesized 2-hydroxy-2-[N-(substituted)-3-oxoisoindolin-1-yl]-1H-indene-1,3(2H)-diones. Furthermore, it seems that the reaction mechanism involves a radical pathway.