Mechanism of the Chirality Transfer

All four chiral auxiliaries are available derivatives of ephedrine. Structurally, they are vicinal amino-alcohols, which are able to act as l,4-N,0-bidentate ligands for many metal cations. The stability of such complexes generally enhances with the hardness of the central metal ion [17]. 

This result indicated that the lithium aggregates equilibrated at 0°C to form an effective complex in the transfer of chirality. The experiments also revealed a nonlinear effect (NLE), suggesting that more than 1 mol of chiral auxiliary was involved in the chirality transfer (more detailed discussion about the origin of non-linearity in chirality transfer is given in Chap. 11). 

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