This paper describes our work developing a strategy for the construction of
the typical core structure of the Stemona alkaloids. The approach is to co
ntrol the relative stereochemistry of the groups on the core 1-azabicyclo[5
.3.0]decane ring system by a [3,3] sigmatropic rearrangement of an acylimmo
nium. ion followed by selective reduction. After optimization, this reactio
n sequence afforded the desired diastereomer in 62% yield. Further efforts
were directed toward elaboration of the characteristic butyrolactone substi
tuent.