The Hydrated Structure Factor in Additive Effect on Enantioselective Organocatalytic Transfer Hydrogenation Reactions with Hantzsch Esters

Acid additives were frequently used in amine-catalyzed asymmetric catalysis as a practical strategy for the promotion of reaction activity/selectivity with a reduced amount of chiral catalyst. A fact is that the acid additives were discovered mostly by chance rather than by a logic prediction. Two bioinspired hydrated mechanisms for the organocatalytic transfer hydrogenation reactions were proposed in this work. And the proposed different acid-water-imine hydrated structures involved mechanism could well explain the additive effect supported by the reported experimental data. The new insight shows promise for assisting a logic acid additive screening in cationic imine-mediated asymmetric catalysis.