Organocatalytic Applications of Cinchona Alkaloids as a Potent Hydrogen-bond Donor and/or Acceptor to Asymmetric Transformations: A Review

With the requirements of green and high-selectivity synthesis, organocatalytic asymmetric transformations of achiral substrates into specific enantiomers or diasteroisomers have gained enormous significance from academic, industrial and environmental perspectives. These transformations are usually catalyzed by axially dissymmetric small chiral organic molecules or by organic compounds bearing chiral center(s). The stereochemical outcome of the enantiomerically or diastereomerically enriched product is normally governed by weak non-covalent hydrogen-bond interactions of the electrophilic/nucleophilic substrates with potent hydrogen bond-donor and/or acceptor functional groups present on the rigid chiral backbone of the organic catalyst. The current review intends to cover recent development in the design of chiral cinchona alkaloids bearing multiple functional groups and their role in organocatalytic asymmetric synthesis.