Double Thiol-Chiral Brønsted Base Catalysis: Asymmetric Cross Rauhut–Currier Reaction and Sequential [4 + 2] Annulation for Assembly of Different Activated Olefins
journal contributionposted on 26.08.2019, 11:33 authored by Zhi Zhou, Qing He, Ying Jiang, Qin Ouyang, Wei Du, Ying-Chun Chen
A double catalytic system combining 2-mercaptobenzoic acid and a chiral phase transfer substance was disclosed for the intermolecular cross Rauhut–Currier reaction of 2-cyclopentenone and isatin-based alkylidene malononitriles. The resulting chiral adducts were sequentially assembled with diverse electron-deficient olefins to furnish highly enantioenriched cyclohexane derivatives (up to 96:4 er, >19:1 dr). A similar catalytic system of 2-mercaptobenzoic acid and quinine was further developed for the reaction of 2-cyclopentenone and α-cyano chalcones (up to 96.5:3.5 er).