microwave-assisted reaction optimization and synthesis of novel n-ethylidene-4-(furan-2-yl) oxazol-2-amine derivatives

This study reports the microwave-assisted synthesis of 4-(furan-2-yl) oxazole-2-amine and its schiff base derivatives as sustainable alternatives to conventional methods. optimization experiments using acetophenone–urea as a model system demonstrated ethanol (0.5–1.5 ml) under 750 w microwave irradiation for 40–60 s is the most efficient condition, yielding 90–92%. these conditions were successfully applied to a furan-based substrate, confirming the reproducibility and scalability of the methodology. the target compound, 4-(furan-2-yl) oxazole-2-amine, was further condensed with a series of aromatic aldehydes to afford schiff base derivatives (ks3, ks7, ks10, ks15, ks16, ks18, ks19, and ks20) in good to excellent yields. microwave-assisted reactions markedly reduce reaction times (≤2 min) compared to conventional reflux (3–5 h) while minimizing solvent use, aligning with the principles of green chemistry. structural elucidation of all the synthesized compounds was achieved using ftir, 1h-nmr, 13c-nmr, and mass spectrometry, which confirmed the oxazole core and imine linkages. substituent effects were evident, with nitro, dimethylamino, and trifluoromethyl groups influencing chemical shifts, absorption bands, and physicochemical properties, such as melting point and solubility. these derivatives exhibited distinct structural and electronic variations, underscoring their potential as scaffolds for further pharmacological investigations. overall, this work demonstrates a robust, rapid, and eco-friendly protocol for generating heteroaryl imine hybrids, providing a valuable platform for future structure–activity relationships and bioactivity studies.