Asymmetric hetero-Diels–Alder reactions of glyoxylate esters and Danishefsky's diene catalyzed by various chiral bis (oxazoline)–lanthanide complexes afforded the corresponding aldol adducts, which upon treatment with trifluoroacetic acid, furnished the hetero-Diels–Alder product in up to 77% enantiomeric excess and 73% isolated yield.
