Sustainable synthesis of bis(indolyl)methane scaffolds catalyzed by CuO nanoparticles immobilized with triethylammonium bistriflimide ionic liquid

Abstract

The pursuit of efficient, recyclable, and environmentally benign catalytic systems continues to be a cornerstone of modern sustainable chemistry. This work discloses the unprecedented fabrication of CuO nanoparticles immobilized with the triethylammonium bistriflimide ionic liquid, (CuO[HN(C₂H₅)₃[NTf₂]), resulting in a robust and efficient heterogeneous catalytic platform. Detailed characterization confirmed the robust incorporation of the ionic liquid and the preservation of the material's nanoscale structural integrity. To demonstrate its catalytic potential, the composite material was employed in a sustainable and efficacious strategy for the development of bis(indolyl)methane scaffolds. The transformation proceeded efficiently at ambient temperature in an environmentally benign green solvent system, affording the targeted bis-heteroaryl conjugates in moderate to excellent yields, with intermediates (II, III) detected by HRMS. The methodology demonstrated broad functional group tolerance, accommodating a wide array of aldehydes, including aryl, hetero-aromatic, and aliphatic substrates, thereby underscoring its synthetic versatility. Moreover, the molecular structure of product 3bb was unambiguously validated through single-crystal X-ray diffraction (SC-XRD) analysis.