Chemistry

Gilded Coupling

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Science  21 Aug 2009:
Vol. 325, Issue 5943, pp. 921
DOI: 10.1126/science.325_921b

Contrary to gold's historical reputation as an inert element, increasingly versatile examples of catalysis by nanoparticulate morphologies of the precious metal are emerging. Zhou et al. now show that even larger particles of bulk gold (5 to 50 µm in diameter) can promote organic coupling reactions. Carbene precursors such as diazoalkanes (R2C=N=N, where R is an alkyl group) and 3,3-diphenylcyclopropene react in the presence of this gold powder to form olefins through apparent carbene coupling at the metal surface. Cyclopropanation reactions with added styrene were also observed. The surface morphology affected reactivity: Initially reduced powders (incorporating residual carbon) were less active than the smoother, shinier surfaces that formed after a round of diazo substrate couplings.

J. Am. Chem. Soc. 131, 10.1021/ja900653s (2009).

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