Using Rare-Earth Metals for Water-Tolerable Lewis Acid Catalysis

Significance

This example demonstrates the use of water-tolerable chiral rare-earth-metal complexes for asymmetric hydroxymethylation and aldol reactions. Many chiral Lewis acids decompose readily in aqueous media and therefore are not applicable unless the reagents are highly purified and dried. In this particular case formaldehyde is in an aqueous medium and therefore water compatibility of the catalyst becomes very important; this paper resolves this issue.