Designing proline-based kiral ligands and their asymmetric induction effects on aldol reactions: An experimental and theoretical approach

Studies concerning optically active compounds accopy very important places both in industry and academic fields. Asymmetric catalysis is considered as an ideal method for synthesing optically active compounds. Asymmetric induction in stereochemistry is described as the preferential formation of one enantiomer or diastereoisomer over the other in a chemical reaction as a result of the influence of a chiral feature present in the substrate, reagent, catalyst or environment, which is a key element in asymmetric synthesis, first introduced by Emil Fischer based on his work on carbohydrates. The field received three Nobel Chemistry prizes for its importance. Since the discovery of L-proline-catalysed reactions, this unique amino acid has been extensively studied as an organocatalyst. The study involves designing 4 new asymmetric organocatalysts with C2 symmetry based on proline and test their effects in asymmetric Aldol reactions. Molecular modelling approaches have also been applied to predict the reasons behind the enantiomeric desrimination of Aldol reactions induced by these organocatalysts. Amber9 was used to predict molecular dynamic features of organocatalysts while Gaussian03 was used to predict the energy levels of reactant, transition and product states of catalysed Aldol reacions in order to understand the enantiomeric descrimination induced by these organocatalyst. The qunatum mechanical calulation was performed at b3lyp/6-31+g(d) level.