Environmentally benign synthesis of functionalized spiro[indoline-3,2′-pyrrole]-2,5′-diones via an aqueous-mediated squaric acid organocatalyzed protocol and their in vitro

An efficient, eco-friendly protocol has been developed for the synthesis of functionalized spiro[indoline-3,2′-pyrrole]-2,5′-diones 4(a–r) via a one-pot multicomponent reaction in an aqueous medium using squaric acid as a reusable organocatalyst.