The Asymmetric Synthesis of the [D8]‐Labeled (−)‐(S)‐Dihydroxyverbacine,the Terminal Precursor in the Biogenesis of the Macrobicyclic Spermine Alkaloids Aphelandrine and Orantine

The asymmetric synthesis of the unlabeled and [D₈]‐labeled terminal precursors, 4 ((−)‐(S)‐dihydroxyverbacine) and 19 , respectively, in the biogenesis of the spermine alkaloids aphelandrine ( 5 ) and orantine ( 6 ), respectively, is described. A partial synthesis of the alkaloid (−)‐(S)‐[(E)‐4‐methoxycinnamoyl]buchnerine ( 10 ) is also presented.