Theoretical study of stereoselectivity for syn-selective cross-aldol reactions of aldehydes catalyzed by chiral diamine organocatalysts

摘要

Quantum mechanical calculations have been performed to study the stereoselectivities in the direct cross-aldol reactions of aldehydes catalyzed by simple chiral diamines.The detailed computational studies on the stereochemistry-controlling step of the subject reactions have been presented by DFT calculations at the B3LYP/6-31G* level.The poor agreement between the calculated and the observed diastereomeric ratio and enantiomeric excess values is obtained for all diamines catalysts.Further M06-2X calculations can provide a reasonable explanation for the observed syn-selectivities of the asymmetric cross-aldol reaction between propionaldehyde and 4-nitrobenzaldehyde.