Structural biochemistry. Part VIII. 9-Amino-(9-deoxy)-cinchona alkaloids

Lithium aluminum hydride reduction of the oximes derived from quinidinone (IIIa) and cinchonidinone has been used to obtain 9-amino-(9-deoxy)quinidine (IIb) and the corresponding 9-amine in the cinchonine series. Based on optical rotatory dispersion measurements, tentative stereochemical assignments for the amines have been proposed. A major objective of the present study, synthesis of 9-(benzyloxycarbonylthreonylseryl)amino-(9-deoxy)quinidine (IId) was achieved by condensing amine (IIb) with benzyloxycarbonylthreonylserine azide. In connection with the preparation of quinidinone and cinchonidinone, reaction between, e.g., quinine and acetic anhydride-dimethyl sulphoxide gave exclusively the corresponding 9-acetoxy-derivative.