Diastereoselective synthesis of a “chiral-at-Ru” secondary phosphine complex

Synthesis of the half-sandwich ruthenium complex [RuCl(η5-indenyl){P(But)(Ph)H}(PPh3)], 2, containing an unsymmetrically-substituted secondary phosphine, is described. A 60:40 kinetic distribution of the resulting diastereomers 2a and 2b shifts in solution at room temperature to give predominantly 2a. The relative stereochemistries at ruthenium and the secondary phosphine in each diastereomer have been assigned based on 1H NOESY NMR and crystallographic data.

Diastereomers of the chiral, half-sandwich ruthenium complex of a secondary phosphine exhibit epimerization in solution.Figure optionsDownload as PowerPoint slideResearch highlights
► Chiral, half-sandwich ruthenium complex of a secondary phosphine made in diastereomeric excess.
► Diastereomer epimerization in solution observed by NMR.
► Relative stereochemistry at Ru and P assigned using NOESY NMR and crystallography.