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Homologation and functionalization of carbon monoxide by a recyclable uranium complex

Gardner, Benedict M., Stewart, John C., Davis, Adrienne L., McMaster, Jonathan, Lewis, William, Blake, Alexander J., Liddle, Stephen T.
Proceedings of the National Academy of Sciences of the United States of America 2012 v.109 no.24 pp. 9265-9270
alkynes, carbon, carbon monoxide, feedstocks, halides, isotope labeling, petroleum, stable isotopes, uranium
Carbon monoxide (CO) is in principle an excellent resource from which to produce industrial hydrocarbon feedstocks as alternatives to crude oil; however, CO has proven remarkably resistant to selective homologation, and the few complexes that can effect this transformation cannot be recycled because liberation of the homologated product destroys the complexes or they are substitutionally inert. Here, we show that under mild conditions a simple triamidoamine uranium(III) complex can reductively homologate CO and be recycled for reuse. Following treatment with organosilyl halides, bis(organosiloxy)acetylenes, which readily convert to furanones, are produced, and this was confirmed by the use of isotopically ¹³C-labeled CO. The precursor to the triamido uranium(III) complex is formed concomitantly. These findings establish that, under appropriate conditions, uranium(III) can mediate a complete synthetic cycle for the homologation of CO to higher derivatives. This work may prove useful in spurring wider efforts in CO homologation, and the simplicity of this system suggests that catalytic CO functionalization may soon be within reach.