Uranium Complex Fuses CO To Make Furanones

A simple uranium complex not only performs the challenging but potentially industrially valuable task of fusing together two CO molecules, but the complex is readily recycled after the reaction. Chemists have had difficulty finding an efficient way to manipulate the muscly C≤O bond and coax the molecule to form oligomers, such as the dimer ethyne diolate, ^–O–C≤C–O^–. And even when metal complexes have been able to do the job, they have not been recyclable. Now, Stephen T. Liddle and colleagues at the University of Nottingham, in England, report a relatively simple process involving a triamidoamine uranium(III) complex that illustrates the potential for synthesizing functionalized CO homologs (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1203417109). Under mild conditions the uranium complex forms a species containing the O–C≤C–O building block. This molecule is then treated with an organosilyl halide to form a bis(organosiloxy)acetylene, which can be converted to a furanone (shown) in a ring-closing step. In addition, triamidoamine uranium(IV) iodide forms during the reaction, making it possible to create a cycle to restore the uranium(III) complex. “The simplicity of this system suggests that catalytic CO functionalization may soon be within reach,” Liddle and coworkers write.