The enantiomeric excess obsd. for the exo-adduct from the Lewis acid catalyzed Diels-Alder reaction between cyclopentadiene and methacrolein can be increased up to 21% by simple modification of the electronics of the arom. ring in a series of stilbene-derived diol ligands, suggesting that the proposed face-face π-π interaction between the catalyst and the dienophile can be modulated by altering the electron d. on the arom. ring.
- aromatic rings