An Evolving Insight into Chiral H-Bond Catalyzed Aza-Henry Reactions: A Cooperative Role for Noncovalent Attractive Interactions Unveiled by Density Functional Theory.

The role of cooperative effects arising from noncovalent attractive interactions as a vital factor governing stereoinduction in chiral H-bond catalyzed aza-Henry reactions is reported. Supporting this finding were density functional theory (DFT) calculations which revealed a shape and size dependency existed between the catalyst and substrates that when matched lead to high enantioselectivity, as reflected by favorable activation parameters. Associated with optimal catalyst and substrate pairing were a closed catalytic binding pocket and a synclinal orientation of the substrates that reinforced favorable stereoelectronic effects and dispersive type forces. Meanwhile, unfavorable steric interactions were found to be a dominant effect controlling diastereoselection.