Cycloadducts from highly functionalized nitrones and oximes as ligands in the enantioselective addition of diethylzinc to benzaldehyde

Abstract

Highly diastereoselective intramolecular cycloaddition of nitrones 5–7 and 16, as well as oximes 11–13 that are easily accessible from diethyl (R,R)-tartrate, affords bicyclic compounds 8–10 and 17. The tetracyclic compound 14 is formed as the main product by an intramolecular domino reaction of dioxime 11. Some of the bicyclic compounds and the tetracyclic compound 14 are tested as chiral ligands in the enantioselective addition of diethylzinc to benzaldehyde. An ee of 93% was achieved in the presence of the best ligand.