Synthetic Studies on the Lycopodium Alkaloids. III. Synthesis of a Key Intermediate, Ethyl Octahydro-4aβ-hydroxy-7β-methyl-10-oxo-1H-5, 8α-propanoquinoline-1-carbamate, for the Lycopodium Alkaloids

Abstract

A tricyclic key intermediate (II) for the lycopodine and the lycodine type of alkaloids was synthesized from 9-oxobicyclo (3, 3, 1) nonene system (IV) by a series of reactions shown in Chart 2. Dehydration of II with strong acid resulted in the rearrangement of carbon skeleton into an enamino-ketone (III). The stereochemistry of stereoselective C₉-alkylation in IV with sulfonium ylid was also discussed.