In 2000, List et al. reported an intermolecular asymmetric aldol reaction which uses proline as a catalyst.¹⁾ List’s report served as a trigger to stimulate research activities in the field of asymmetric organocatalysis.²⁾ The proline derivative 1, which was recently developed by Nakamura et al., shows high TON as an asymmetric catalyst for the asymmetric aldol reaction. Convolutamydine A is an alkaloid that was obtained with high enantioselectivity by using only 0.5 mol% of 1 owing to this high catalytic activity.³⁾ Nakamura shows the reaction mechanism to involve hydrogen bonding between the amide proton of the starting material and the 2-thienyl sulfur atom in 1.