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.