Fe₂O₃ Nano‐Catalyst Mediated Oxidative Decarboxylation CH Acylation/Benzoylation of 3‐Alkylidene‐2‐Oxindoles With α‐Keto Acids

ABSTRACT

We successfully employed an environmentally friendly synthesized heterogeneous Fe₂O₃ nano‐catalyst‐mediated one pot approach to β CH bond acylation of 3‐Alkylidene‐2‐Oxindoles via oxidative decarboxylation of α‐keto acids. This method enabled the activation of C_sp2‐H bonds, resulting in the formation of C_sp2‐C_sp2 single bonds and the generation of highly substituted derivatives of (E)‐2‐(2‐oxoindolin‐3‐ylidene)‐1‐aryl‐3‐substituted‐propane‐1,3‐diones and (E)‐3‐oxo‐2‐(2‐oxoindolin‐3‐ylidene)‐3‐substituted‐propanoates. The synthesized non‐toxic Fe₂O₃ nano‐material was meticulously characterized through FT‐IR, powdered XRD, HRTEM, EDX, BET, and ICP‐MS analyses. This heterogeneous catalyst can be conveniently recovered with a magnetic field and reused in subsequent reactions. This method offers excellent functional‐group tolerance, efficient substrate yield in less time, simple workup, and a recyclable catalyst.