Solvent-Free Biginelli Reaction Using Heterogeneous CuS-Carbon Nanoflakes Nanocomposites

Herein, we developed copper sulfide (CuS) nanoparticles (NPs)-decorated carbon nanoflakes (CNFs) nanocomposites (CuS-CNFs) and used it as an efficient heterogeneous catalyst for a very fast one-pot solvent-free multicomponent Biginelli reaction via dehydrative condensation of aromatic aldehydes with acetylacetone/ethyl acetoacetates and urea/thiourea, yielding 3,4-dihydropyrimidinones/thiones (DHPMs) derivatives. The reaction was completed within 5 min with a high yield of the desired products. The reaction exhibited a broad substrate scope, tolerating both electron-withdrawing and donating substituents with good to excellent yield. The reactions were monitored by gas chromatography–mass spectrometry (GC–MS), and further the products were confirmed through 1 H NMR, 13 C NMR, and mass spectrometry analysis. The plausible reaction mechanism was explored based on mass spectrometry analysis of the intermediates and a literature survey. The catalytic performance of the CuS-CNFs nanocomposite can be attributed to the high-surface area of the CNFs and the uniform dispersion of CuS NPs on the surface of CNFs, which provide more active sites. Additionally, the heterogeneous nature of the CuS-CNFs facilitates easy recovery and recyclability under solvent-free reaction conditions, with the catalyst retaining its activity over up to five consecutive cycles without significant loss. This transformation presents several advantages, including very short reaction time, solvent-free reaction condition, good compatibility with various substrates, reusability, and operational simplicity.