NMR studies on the structure of a lithium amide–chiral diether complex for an asymmetric reaction

The combination of a chiral diether ligand and a lithium benzyl(trimethylsilyl)amide is a powerful lithium amide reagent for asymmetric conjugate amination of enoate in a toluene solvent. The structure of the chiral diether–lithium amide complex in solution was analyzed by low-temperature NMR. 6Li NMR suggested the formation of a cyclic heterodimer. The stereochemical pathway is predictable based on the structure of the lithium amide–chiral diether complex.