Effect of Protonation on the Conformation of Cinchonidine

摘要

Cinchona alkaloids,compounds found naturally in the bark of the Cinchona tree,have found a number of applications as Pharmaceuticals for the treatment of malaria and cardiac arrhythmias,as additives for soft drinks,as starting materials for organic synthesis,as chiral resolving agents in fractional crystallization and chromatographic techniques,and as agents for promoting enantioselective transformations in both homogeneous and heterogeneous catalysis.These cinchona,represented here by cinchonidine (Figure 1),are characterized by an aromatic quinoline ring connected to a quinuclidine tertiary amine through a chiral alcoholic carbon.Most of the desirable properties of the cinchona have been traced back to the environment around the chiral linker and appear to involve the participation of the nitrogen in the aliphatic amine.In fact,it has been shown that protonation of that amine severely influences the chemistry of the cinchona,presumably by inducing a change in molecular conformation.