Copper Route to (E)-Alkenes

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Science  28 Jun 2002:
Vol. 296, Issue 5577, pp. 2301
DOI: 10.1126/science.296.5577.2301a

Mild methods exist for reducing alkynes to cis alkenes while leaving other functional groups on the molecule intact. This is more difficult when the trans isomers are desired, because the existing routes are harsher and often require activating functional groups near the triple bond. Trost et al. have modified a synthetic route in which the triple bond is hydrosilylated with a ruthenium complex and then converted to the trans alkene by treatment with tetrabutylammonium fluoride (TBAF). Elevated temperatures (∼80°C) in this last step have limited its general use, but the authors have found that addition of cuprous ion (as CuI) allows the C-Si bond to be cleaved catalytically at much lower temperatures (∼35°C) in high yields. Because CuI buffers the reactivity of TBAF toward other functional groups, in cases where more reactive functional groups are present, the copper complex is used in stoichiometric amounts. — PDS

J. Am. Chem. Soc. 10.1021/ja026457l (2002).

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