Versuche zur Synthese von Strychnopivotin und eine einfache Synthese des Isochinuclidin‐Gerüsts

Experiments Directed to the Synthesis of Strychnopivotine and a New Synthesis of the Isoquinuclidine Framework The 2‐azabicyclo[3.3.1]nonane (keto‐morphane) 2 can be transformed via the enamine 4 into the dithio‐dioxolane derivative 6 of the corresponding 6,7‐diketone. After hydrolysis of the dithio group and formation of the monoprotected diketone 3 Fischer cyclisation yields the isodasycarpidone derivative 7, an intermediate to a synthesis of strychnopivotine (1a). — In view of the likewise desired tricyclus 8 for a synthesis of strychnopivotine, a cyclisation of ketoamide 9 was tried under standard conditions. By aldol‐ring closure, however, not the expected 2‐azabicyclo[3.3.1]nonane 14 was formed, but instead the 2‐azabicyclo[2.2.2]octane derivative (isoquinuclidine) 15. The preparation of 9 via the intermediates 10–13 is described.