Synthetic transformations of higher terpenoids: XIV. Heterocyclization reactions of 15,16,18-ricarboxylabdadiene. New nitrogen-containing diterpenoids

The oxidation of methyl lambertianate with Jones’ reagent formed the corresponding anhydride which reacted with amines to form N-substituted terpenoid maleimides. New maleimides demonstrated high activity and stereoselectivity in the Diels-Alder reaction with cyclopentadiene. The condensation of the diterpenoid anhydride with hydrazines led to the formation of derivatives of 3,6-dioxo-1,2,3,6-tetrahydropyridazines of labdane type.