β-Amino alcohols derived from L-valine were used as chiral ligands in oxazaborolidine reductions of ketones. Structural modifications, such as the introduction of alkyl groups on the carbinol carbon and the nitrogen atoms, were shown to influence unfavourably the enantioselectivity. In contrast, the addition of diethyl zinc to aldehydes occurs with enhanced ee's using these modified inductors, which permit to reach useful enantioselectivities with ...
[Imai, Toshiro; Tamura, Tadashi; Yamamuro, Akira; Sato, Tsuneo; Wollmann, Theodor A.; et al. Journal of the American Chemical Society, 1986 , vol. 108, # 23 p. 7402 - 7404]