抄録
The total synthesis of ibogamine (1b) epiibogamine (1d) and desethylibogamine (1c) was accomplished by applying a new synthetic method for bridged aziridines as well as isoquinuclidines. This new method consists of the oxidation of δ,ε-unsaturated primary amines such as 4 with lead tetraacetate giving the highly strained bridged aziridines 5 which upon treatment with an acylating agent were cleaved mainly to isoquinuclidine derivatives 8. 1-Azatricyclo[3,2,1,0^<2,7>octane 5a obtained by this new method was cleaved readily with indole acetic anhydride in acetone to give the amorphous 13 which upon hydrolysis with aqueous potassium carbonate in methanol afforded the hydroxy derivative 14. The oppenauer oxidation followed by cyclization with 1,2-equiv. p-toluenesulfonic acid in benzene yielded the tosylate 16 which was then treated with sodium methoxide in boiling methanol to give the methoxy lactam 17. This compound on treatment with lithium aluminum hydride unexpectedly gave the enamine 18 which was hydrogenated on palladium to give the methoxy base 19. Finally, reductive elimination of the 18-methoxy group was accomplished smoothly with lithium aluminum hydride yielding desethylibogamine. Likewise, 21 and 22 were transformed to ibogamine (1b) and epiibogamine (1d) respectively.
