Isolation of <i>trans-</i>2,5-Bis(methoxycarbonyl)ruthenacyclopentane by Oxidative Coupling of Methyl Acrylate on Ruthenium(0) as an Active Intermediate for Tail-to-Tail Selective Catalytic Dimerization

The <i>trans</i>-bis(methoxycarbonyl)ruthenacyclopentane complex [<i>trans</i>-Ru{C<sup>2</sup>H{C(O<sup>1</sup>)OMe}C<sup>3</sup>H<sub>2</sub>C<sup>4</sup>H<sub>2</sub>C<sup>5</sup>H{C(O<sup>2</sup>)OMe}-κ<sup>1</sup><i>C</i><sup>2</sup>,κ<sup>1</sup><i>O</i><sup>1</sup>,κ<sup>1</sup><i>C</i><sup>5</sup>,μ-κ<sup>1</sup><i>O</i><sup>2</sup>}(η<sup>4</sup>-1,5-COD)]<sub>2</sub> (<b>2</b>) and the acetonitrile adduct Ru[C<sup>2</sup>H(CO<sub>2</sub>Me)CH<sub>2</sub>CH<sub>2</sub>C<sup>5</sup>H(CO<sub>2</sub>Me)-κ<sup>1</sup><i>C</i><sup>2</sup>,κ<sup>1</sup><i>C</i><sup>5</sup>](η<sup>4</sup>-1,5-COD)(NCMe)<sub>2</sub> (<b>3</b>) have been obtained from the reaction of Ru(η<sup>6</sup>-naphthalene)(η<sup>4</sup>-1,5-COD) (<b>1</b>) with methyl acrylate and are active for the Ru(0)-catalyzed dimerization of methyl acrylate. Thus, complex <b>3</b> catalyzes the tail-to-tail dimerization of methyl acrylate in 52% yield at 140 °C in THF, suggesting that this dimerization proceeds by the oxidative coupling mechanism.