0000000000563566
AUTHOR
Csaba Szántay
Synthesis of vinca alkaloids and related compounds LX. A simple transformation of apovincamine into vincamine
Abstract The 15α-chloro-vincamine derivative 2 was prepared and proved to be key intermediate of a two-step transformation of apovincamine into vincamine. The structure of 2 was established via detailed NMR and X-ray investigations.
Dimerization of (+)-Lysergic Acid Esters
Dimer isomer mixtures, characterized by a bridgehead C8-C8' bond, (6a-7a; 6b-7b) were obtained from (+)-lysergic acid methyl or ethyl ester (1b; 1c) in a solution of methanol or ethanol. The isomers were separated, and their structures were determined by detailed NMR measurements and X-ray analysis. Density functional theory was applied to provide insight into the reaction mechanism. Based on an extended examination and the theoretical calculations, a plausible reaction sequence leading to dimers is also presented. The proposed mechanism has been verified by detecting the formation of the superoxide radical anion (O 2 * -).