Magnetic decorated 5-sulfosalicylic acid grafted to chitosan: A solid acid organocatalyst for green synthesis of quinazoline derivatives

Abstract

In this research, a new magnetically decorated multifunctional solid acid was designed and prepared conveniently by grafting of 5-sulfosalicylic acid (SSA) onto the chitosan (CS) backbone using toluene-2,4-diisocyanate (TDI) linker for the first time. The obtained magnetic biopolymeric nanomaterial, CS-TDI-SSA-Fe3O4, was properly characterized by using spectroscopic, microscopic, or analytical methods including FT-IR, EDX, XRD, BET, FESEM, TGA, and VSM. The supramolecular CS-TDI-SSA-Fe3O4 nanocomposite was investigated, as a heterogeneous organocatalyst, to promote the three-component synthesis of 2,3-dihydroquinazoline-4(1H)-one derivatives under green conditions. The solid acidic CS-TDI-SSA-Fe3O4 nanocatalyst demonstrates highly efficient activity for the synthesis of a wide range of quinazoline derivatives, as an important pharmaceutical scaffold, through the multicomponent strategy. The reaction proceeds very well in the presence of CS-TDI-SSA-Fe3O4 solid acid in EtOH to afford corresponding 2,3-dihydroquinazoline-4(1H)-one (DHQ) derivatives in high to excellent yields. The key advantages of the present protocol are the use of a novel, renewable, biopolymeric, and biodegradable solid acid as well as a simple procedure for the preparation of the hybrid material. Furthermore, the CS-TDI-SSA-Fe3O4 catalyst can be used at least five times for the synthesis of DHQ derivatives with a slight decrease in its catalytic activity.