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.