فهرست نشریات علمی دسترسی آزاد ایران

A green and efficient multicomponent strategy has been developed for the synthesis of 4H-pyrimido[2,1-b]benzothiazole derivatives employing graphene oxide nanosheets functionalized with an acidic ionic liquid (GO-Si-Pr-Creatinine-SO₃H) as a reusable heterogeneous catalyst. The catalyst was synthesized through surface modification of graphene oxide with 3-chloropropyltrimethoxysilane, subsequent immobilization of creatinine, and sulfonation. Its structure and morphology were confirmed by FT-IR, XRD, SEM, and EDX analyses. The condensation of 2-aminobenzothiazole, aromatic aldehydes, and β-ketoesters under solvent-free conditions afforded the target products in excellent yields (92–98%) within 20–40 min at 80–90 °C, requiring only moderate catalyst loading (30–40 mg). The reaction mechanism proceeds through in-situ Knoevenagel condensation, Michael addition, and intramolecular cyclization, in which the catalyst acts as a Lewis acid to activate carbonyl groups. The catalyst demonstrated outstanding reusability for at least seven consecutive cycles with minimal loss of activity. The synthesized derivatives were fully characterized by FT-IR, 1H-NMR, and 13C-NMR spectroscopy. Biological evaluation against representative Gram-positive and Gram-negative bacterial strains revealed notable antibacterial activity, comparable to standard pharmaceutical agents, underscoring the potential of this methodology in sustainable heterocyclic synthesis and biomedical applications.