Resolution and Diels-Alder catalysis with planar chiral arene-tethered ruthenium complexes

Planar chiral arene-tethered ruthenium complexes were applied to the Diels-Alder reaction of methacrolein and cyclopentadiene, with enantiomeric excesses up to 70%. The influence of a chiral phosphoramidite ligand on the catalytic selectivity was examined, along with counterion effects. The potential of asymmetric activation using the mixture of diastereomers formed from a racemic tethered complex and an enantiopure phosphine directly in the catalysis was investigated.