Asymmetric reduction of ethyl benzoylformate with chiral NADH model systems: Mechanistic and stereochemical consideration of the reactions based on the complexation properties of the model compounds

Asymmetric reductions of ethyl benzoylformate were conducted by use of NADH model compounds with C₁ or C₂ symmetry in the presence of magnesium perchlorate. It was found that NADH model compounds which form 2 : 1 chelation complexes with the magnesium ion showed the dependence of optical yield on the reaction conversion. The stereochemical behaviors of the model compounds were classified into three reaction types on the basis of the component ratio in the chelation complex between the reductants and the magnesium ion.