Quinolizidines. XI. Structure determination of the Alangium alkaloid desmethylpsychotrine through synthetic incorporation of ethyl cincholoiponate into (+)-9-demethylpsychotrine

With a view to establishing the structure of the Alangium alkaloid desmethylpsychotrine, (+)-9-demethylpsychotrine [(+)-1] has been synthesized from ethyl cincholoiponate [(+)-6] and 3-benzyloxy-4-methoxyphenacyl bromide by the "cincholoipon-incorporating method" through the intermediates (+)-7,8,10-(+)-14,and (+)-17-(+)-22. The identity of synthetic (+)-1 with natural desmethylpsychotrine unequivocally established the structure of this alkaloid