Homo-and Heterocomplexes of Sodium and Lithium Amides-Structures in Solution

摘要

Addition of the chiral amine (S)-methyl(1-phenyl -2-pyrrolidinoethyl)-[~(15)N]amine (1) to a large excess of nBuNa resulted in the formation of a mixed sodium amideBuNa complex.This is the first observation of such a complex.Addition of nBuLi to the chiral sodium amide dimer 3 gave a new mixed lithium/sodium amide 5.The use of ~15N,~6Li coupling constants showed that the lithium in 5 occupied the tetracoordinated site.The use of chiral sodium amide 3 in the desymmetrization of cyclohexene oxide gave a modest enantiomeric excess (ee) of 37%.The corresponding lithium amide gave an ee of 70% of the same enantiomer.This is the first example of the comparison of asymmetric induction by sodium as cation with that of lithium.