Chiral Quaternary Ammonium Salt-Catalyzed Enantioselective Addition Reactions of Hydantoins

We herein report a protocol for the asymmetric 1,4-addition of hydantoins to various Michael acceptors by utilizing Cinchona alkaloid-based chiral quaternary ammonium salt catalysts. Various products were obtained with moderate to good enantioselectivities and accompanying computational investigations helped to identify key interactions responsible for the observed selectivity. DFT calculations along with non-covalent interaction plots reveal the presence of numerous stabilizing non-classical hydrogen bonding interactions along with other non-covalent interactions between the chiral quaternary ammonium salt and hydantoin molecule in the C−C bond forming transition states leading to the formation of the products. In addition, a first proof-of-concept for an analogous a-sulfanylation reaction, albeit with poor selectivity, is reported as well.