Theoretical study of the catalytic effect of a new L-proline derived organocatalyst designed for asymmetric nitoaldol reaction

L-Proline as an efficient chiral organocatalyst has two functional groups that act both as acid and base and can also facilitate some chemical reaction such as aldol and nitroaldol reactions [1-2]. A proline amide containing two hydrogen bond donor groups show more organocatalytic effect in nitroaldol reaction. Our main aim is designing a new hydrogen bond-donating bifunctional aminocatalyst that is derived from L-proline to increasing the rate and steroselectivity of asymmetric nitroaldol reaction [3-5]. We proposed a completely different mechanism for nitroaldol reaction based on non-covalent interactions by 1 as the organocatalyst. Then the stereoselectivity of the reaction was evaluated by comparison of the activation energies of the two concurrent reaction paths. The pathways was computationally investigated in DMSO as solvent at room temperature by DFT method at the B3LYP/6-31G**/PCM level of theory. The work introduces a more suitable and reasonable pathway to explain the distribution and stereoselectivity of the reaction product.