Stereoselective synthesis of trans-dihydronarciclasine derivatives containing a 1,4-benzodioxane moiety

摘要

Some new trans-dihydronarciclasine derivatives containing a 1,4-benzodioxane moiety were stereoselectively synthesised using our feasible and efficient method developed recently. These new phenanthridone alkaloid analogues were obtained in both racemic and optically active forms. High enantioselectivities (up to 99% ee) were achieved by applying (8S,9S)-9-amino(9-deoxy)epiquinine as an organocatalyst. Due to a side reaction, various methoxyphenanthridine regioisomers were also prepared which afforded further synthetic trans-dihydronarciclasine analogues modified in the ring A of the phenanthridone scaffold.