1985 年 33 巻 10 号 p. 4202-4211
A new elaboration method for the 2-azabicyclo [2.2.2] octane ring via an intramolecular Michael reaction has been developed and applied to the total synthesis of (±)-ibogamine (1) and (±)-epiibogamine (2). The unsaturated ester (9) derived from ethyl 1, 6-dihydro-3 (2H)-pyridinone-1-carboxylate (3a) was reacted with potassium carbonate or sodium hydride to provide two 2-azabicyclo [2.2.2] octanone derivatives (19 and 20), the stereochemistry of which was confirmed by chemical evidence. By a three-step sequence, the esters (19 and 20) were converted into 27 and 36, which were then transformed into the corresponding amides (31 and 40). Cyclization of 31 and 40 followed by reduction with a complex of lithium aluminum hydride-aluminum chloride furnished (±)-epiibogamine (2) and (±)-ibogamine (1), respectively, in good yields.
