The Interaction of Gold(I) Cations with 1,3-Dienes

摘要

The activation of C—C multiple bonds by substituted gold cations [R3PAu]~+ is an important theme in contemporary homogeneous catalysis. However, it is interesting to note that studies of the reactivity of conjugated 1,3-dienes using gold catalysts are relatively rare, although Au/ZrO2 catalysts were found to be effective in the heterogeneous selective hydrogenation of 1,3-butadiene. Furthermore, homogeneous gold catalysts have been used to synthesize function-alized cyclopentadienes and have been employed, for example, in both hydrothiolation and hydroamination of conjugated dienes. In the last of these reactions, a mechanism was suggested whereby the gold center binds η~4 to the diene, which is thus activated towards nucleophilic attack by the amine. Subsequent theoretical studies have refined the mechanism suggesting that the gold actually binds η~2 to the diene prior to attack of the N-nucleophile on the coordinated double bond; protodeauration by proton transfer from the NH2 group to the unsaturated carbon atom regenerates the catalyst. For further advances to be made, a detailed understanding of the interaction of gold centers with 1,3-dienes would of course be beneficial. Since the submission of this manuscript, a related study of gold cation interactions with 1,3-dienes has been published.