The mechanistic studies for linear cross-dimerization between 2,3-dimethylbuta-1,3-diene and styrene by a Ru(0) complex, Ru(η<sup>6</sup>-naphthalene)(η<sup>4</sup>-1,5-COD) (1), are performed both by kinetic and computational studies. This reaction is basically zero-order to both of the diene and styrene concentrations and first-order to the catalyst concentration. The Hammett plot using p-substituted styrenes gives a linear relationship with a positive slope (ρ = +0.482). The deuterium isotope experiment clearly shows the present reaction being a formal 1,4-addition of a C-H bond in styrene to cisoid-1,3-diene. These kinetic studies show the reaction proceeding via oxidative coupling mechanism that is also supported by the DFT calculations.
Hirano, M., Ueda, T., Komine, N., Komiya, S., Nakamura, S., Deguchi, H., & Kawauchi, S. (2015). Mechanistic insights into catalytic linear cross-dimerization between conjugated dienes and styrenes by a ruthenium(0) complex. Journal of Organometallic Chemistry, 797, 174–184. https://doi.org/10.1016/j.jorganchem.2015.08.022