SEARCH Articles Figures Tables Cinchona Cinchona Alkaloid Derivatives with a Sulfonamide, Urea, Thiourea, Squaramide, or Guanidine Function Cinchona Alkaloids as Chiral Ligands in Asymmetric Oxidations Cinchona Alkaloids as Chiral Solvating (Shift) Agents in NMR Spectroscopy