Total synthesis of two novel 5,6,7,8-tetrahydroindolizine alkaloids, polygonatines A and B.
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.
Dinsmore
Andrew
A
Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, P.O. Wits 2050, South Africa.
Mandy
Karen
K
Michael
Joseph P
JP
D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D007202:Indicators and Reagents; D007212:Indolizines / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008968:Molecular Conformation; D011758:Pyrroles / Q000138:chemical synthesis / Q000737:chemistry
D000470:Alkaloids; D007202:Indicators and Reagents; D007212:Indolizines; D011758:Pyrroles