Synthetic Studies on the Lycopodium Alkaloids. II. A Synthesis of a Key Intermediate, 2, 3, 5, 6, 7, 8-Hexahydro-7β-methyl-3-oxo-1H-5, 8a-propenoquinoline, for the Lycopodium Alkaloids

Abstract

The introduction of an amino function on the bridgehead position of the bicyclo (3, 3, 1) nonane ring system has been smoothly achieved by the modified Curtius reaction on some bridgehead carboxylic acids. This method has been applied on 3β-methyl-9-ox-obicyclo (3, 3, 1) non-6-ene-1-carboxylic acid (XIV) to afford the unsaturated aminoketone (XVI) as its hydrobromide via the carbamate. XVI was transformed into the tricyclic lactam (XVIII), via the pyruvamide (XVII) followed by cyclization. XVIII was then reduced via its lactim-ether followed by oxidation to afford 2, 3, 5, 6, 7, 8-hexahydro-7β-methyl-3-oxo-1H-5, 8α-propenoquinoline (XXI) in good yield, which would provide useful intermediate for syntheses of the lycopodium alkaloids.