General Catalyst Control of the Monoisomerization of 1‑Alkenes to <i>trans</i>-2-Alkenes

After searching for the proper catalyst, the dual challenges of controlling the position of the double bond, and <i>cis</i>/<i>trans</i>-selectivity in isomerization of terminal alkenes to their 2-isomers are finally met in a general sense by mixtures of (C₅Me₅)Ru complexes <b>1</b> and <b>3</b> featuring a bifunctional phosphine. Typically, catalyst loadings of 1 mol % of <b>1</b> and <b>3</b> can be employed for the production of (<i>E</i>)-2-alkenes at 40–70 °C. Catalyst comprising <b>1</b> and <b>3</b> avoids more than any other known example the thermodynamic equilibration of alkene isomers, as the <i>trans</i>-2-alkenes of both nonfunctionalized and functionalized alkenes are generated.