Highly enantioselective homogeneous catalysis of chiral rare earth phosphates in the hetero-Diels-Alder reaction

Two types of novel rare earth (RE) complexes were synthesized and used as a chiral Lewis acid catalyst for the hetero-Diels-Alder reaction of carbonyl compounds with the Danishefsky's diene under homogeneous conditions. The Y[(R)-H-8-BNP](3) (3-Y)-catalyzed reaction of aromatic aldehydes and the Yb[(R)-BNP](3) (1-Yb)-catalyzed reaction of phenylglyoxylates afforded the corresponding cycloadducts with excellent optical purities (up to 99% ee) in high yields at room temperature. The successful recycling uses of the scandium catalyst (3-Sc) are also described. (C) 2003 Elsevier Ltd. All rights reserved.