A Versatile and High‐Yield Route to Active and Well‐Defined Catalysts [Ru(bisphosphane)(H)(solvent) ₃ ](BF ₄ )

Abstract

Simple and efficient: Protonation of [Ru(1,2:5,6-η-cod)(η⁶ -cot)] (cod=1,5-cyclooctadiene, cot=1,3,5-cyclooctatriene) with HBF₄ ⋅Et₂ O and then reaction with chiral bisphosphane ligands ($_{\rm PP}^{\frown }$=Me-DuPHOS, BINAP, Tol-BINAP, JOSIPHOS) affords the corresponding [Ru($_{\rm PP}^{\frown }$)(H)(η⁶ -cot)]⁺ or [Ru($_{\rm PP}^{\frown }$)(1,2,3,4,5-η-C₈ H₁₁ ')]⁺ (C₈ H₁₁ '=2,4-cyclooctadienyl; see scheme). Exposure of these cations to H₂ in solvents (sol) such as acetone, methanol, and THF affords [Ru($_{\rm PP}^{\frown }$)(H)(sol)₃ ]⁺ , which are catalysts for (amongst other things) enantioselective hydrogenations of alkenes.