Amidic C–N bond cleavage of isatin: chemoselective synthesis of pyrrolo[2,3,4-kl]acridin-1-ones using Ag NPs decorated rGO composite as an efficient and recoverable catalyst under microwave irradiation

Abstract

We have developed a facile approach for the synthesis of Ag NPs decorated reduced graphene oxide (Ag NPs/rGO) composite via a novel chemical route. This synthetic protocol involves protection, reduction and functionalization of graphene oxide in one step. The as prepared Ag NPs/rGO composite has been characterized by TEM, XRD, SEM, XPS, EDX, UV-Vis, CV, Raman and FT-IR spectra. The results showed that plenty of Ag NPs (∼28 nm) are homogeneously distributed onto the surface of rGO. Further, catalytic application of this fascinating nanomaterial has been utilized for the chemoselective synthesis of pyrrolo[2,3,4-kl]acridin-1-ones via ring-opening or amidic C–N bond cleavage of isatin. The Ag NPs/rGO composite possesses assets of both Ag NPs and reduced graphene oxide, thus, providing enhanced surface acidity with good dispersion ability that is usually missing in Ag NPs alone. After completion of the catalytic reaction, the Ag NPs/rGO composite could be easily recovered by simple filtration and recycled for 7 times without significant loss in its catalytic activity. The recycling and hot-filtration experiments proved the high stability and absence of leaching of the synthesized nanomaterial during the catalytic process. Furthermore, the proposed protocol showed excellent results in terms of green parameters confirming its effectiveness and profound appeal.