Studies on proaporphine and aporphine alkaloids. Part VII. Stereochemistry of reduced proaporphines of Croton sparsiflorus and C. linearis

Abstract

Three new alkaloids, isocrotsparinine (19a), its N-methyl derivative (19b), and (±)-tetraidroglaziovine (12), have been isolated from Croton spariflorus Morong; the stereochemistry of crotsparinine and isocrotsparinine has been defined as (6aR,7aS) and (6aS,7aS), respectively, thus pointing out the stereospecificity of the reduction of the enantiomers of crotsparine (2) during the biogenetic process. Jacularine and base E, two alkaloids of C. linearis Jacq., were assigned the steric formulae (20) and (21), respectively.