NADH model reaction. Importance of hydroxy-groups in the asymmetric reduction of ethyl benzoylformate

Ethyl benzoylformate has been reduced with an NADH analogue, N-{(1S)-2-hydroxy-1-[(S)-α-hydroxybenzyl]ethyl}-1-propyl-1,4-dihydronicotinamide, to give (S)-mandelate in 2.9–28.5% e.e. The asymmetric yield was remarkably affected by the amount of magnesium perchlorate present and continuously changed throughout the reaction. The possible functions of hydroxy-groups in the model compound are discussed in the light of the resultant stereochemical outcome.