All the calculations for the structures reported in this work have been done using density functional theory (DFT). The calculations have been carried out with Turbomole 7.4 56 using the TZVP 57 basis set. Geometry optimizations were performed using the Perdew, Burke, and Ernzerhof (PBE) functional. Dispersion corrections (D3) have been included in all the calculations. Solvent corrections have also been included using the COSMO model, with ε=8.93 and ε=10.90 employed to model dichloromethane, CH2Cl2, when the nucleophile is oxindole and dichloroethane, CH3CH2Cl2, when the nucleophile is the β-keto ester. Therefore, the level of theory employed is PBE-D3/TZVP+COSMO(CH2Cl2) and PBE-D3/TZVP+COSMO(CH3CH2Cl2) respectively. Furthermore, in order to underscore the reliability of the enantiomeric calculations, all the enantioselective transition states have also been further optimized at the M06-2X/TZVP+COSMO(CH2Cl2) level of theory for the case when the nucleophile is oxindole. The values calculated at the M06-2X/TZVP+COSMO(CH2Cl2) level of theory are provided in the Tables . The results (∆∆G # values) show that the trends obtained with the PBE functional are replicated with the M06-2X functional. It is worth mentioning here that the basis set superposition error(BSSE) correction is not included in the current calculations.Rzepa and coworkers have shown that the error due to BSSE becomes significantly less (~0.2 kcal/mol) when they computationally investigated different stereochemical transition states for organocatalytic reactions at the TZVP level. Since the current calculations have been done at the TZVP basis set level, BSSE corrections were therefore unnecessary. The resolution of identity (RI) along with the multipole accelerated RI (marij) approximations have been employed for an accurate and efficient treatment of the electronic Coulomb term in the DFT calculations. Necessary care was taken to ensure that the obtained transition state structures possessed only one imaginary frequency corresponding to the correct normal mode, in order to obtain more reliable energy values for the investigated potential energy surface. In addition, intrinsic reaction coordinate (IRC) calculations were done with all the transition states in order to further confirm that they were the correct transition states, Here, Vmolec is the molecular volume, [X] is the concentration of molecules (mol/L) in solution and N0 is the Avogadro number. The translational entropy can be obtained after considering the free volume correction, and after inserting the value of Vfree in the Sackur-Tetrode equation. The total entropy is then calculated by adding the corrected translational entropy and the entropic contributions from the rotational and vibrational components. Multiwfn were employed for topology analysis. Structures with NCI plots were generated using VMD.