Generation of Enantiomerically Enriched Lithium Indenides by Means of (–)‐Sparteine: Structure, Stereoselective Substitution, and Solvent Effects

Abstract

The thermodynamically controlled equilibration of the configurationally labile diastereomeric lithium 1-alkylindenide/(–)-sparteine complexes in diethyl ether/hexane combined with the crystallization of the diastereomer shown (1; R = Me, nBu) results in a stereoselective addition of these complexes to carbonyl compounds with enantiofacial differentiation at the indenide moiety. In THF/hexane, however, the solvent displaces the chiral ligand and leads to complete racemization of the products.