One-Pot Solvent-Free Synthesis of Diaryl 1,2-Diketones by the Sequential Heck Oxidation Reaction of Aryl Halides with Styrenes

Abstract

A novel one-pot procedure for the synthesis of benzil derivatives was developed by the sequential Heck oxidation reaction of aryl halides (I and Br) with styrenes. In situ-generated stilbene scaffolds were directly converted to the corresponding diaryl 1,2-diketones. In the present transformation, tetrabutylammonium iodide (TBAI) was employed as a dual role reagent, one as a reducing agent in Heck reaction and another as a catalyst in the oxidation step. Mechanistic studies showed that molecular oxygen plays a significant part in the oxidation step. Various derivatives of diaryl 1,2-diketones were synthesized through this protocol in acceptable yields.