Organic & biomolecular chemistry

Total synthesis of two novel 5, 6, 7, 8-tetrahydroindolizine alkaloids, polygonatines A and B

A Dinsmore, K Mandy, JP Michael

Index: Dinsmore, Andrew; Mandy, Karen; Michael, Joseph P. Organic and Biomolecular Chemistry, 2006 , vol. 4, # 6 p. 1032 - 1037

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Citation Number: 25

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 10, formylation of which at C-3 followed by reduction afforded polygonatine A 7. Acetylation of this alkaloid followed by displacement of the acetate with ethanol yielded polygonatine B 5, possibly via an azafulvenium cation.