Wang-OSO3H catalyzed green synthesis of bioactive isoindolo[2,1-a]quinazoline-5,11‑dione derivatives: An unexpected observation

The sulphonic acid-functionalized Wang resin (Wang-OSO3H) was explored as a polymeric and recoverable acidic catalyst for the synthesis of isoindolo[2,1-a]quinazoline-5,11‑dione derivatives under green conditions. Thus the Wang-OSO3H catalyzed MCR of isatoic anhydride, 2-formylbenzoic acid and various amines in pure water afforded a range of desired product in good to excellent (86–94%) yield. The methodology can be performed under open air and is amenable for scale-up synthesis. The catalyst can be recovered and recycled for several times without significant loss of its catalytic activity. The unexpected formation of 2-(1‑hydroxy-3-oxoisoindolin-2-yl)benzamide derivative as observed in one case may allow the access of this class of heterocycles from the same MCR by using an appropriate amine. In silico assessment suggested that the compound 4j, a known inhibitor of TNF-α could be a potential ligand for SARS-CoV-2 with which it formed H-bonds through its OMe and two C=O groups. [Display omitted]