Total synthesis of two novel 5,6,7,8-tetrahydroindolizine alkaloids, polygonatines A and B
Andrew Dinsmore1, Karen Mandy, Joseph P Michael
1Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, P.O. Wits 2050, South Africa.
Organic & Biomolecular Chemistry
|March 10, 2006
Abstract:
The structures of polygonatines A and B, two simple but structurally novel alkaloids, have been substantiated by synthesis. Cyclisation of 4-(1H-pyrrol-1-yl)butanoic acid or its ethyl ester produced 6,7-dihydroindolizin-8(5H)-one , formylation of which at C-3 followed by reduction afforded polygonatine A . Acetylation of this alkaloid followed by displacement of the acetate with ethanol yielded polygonatine B , possibly via an azafulvenium cation.
