Ring-opening aminolysis of sesquiterpene lactones: An easy entry to bioactive sesquiterpene derivatives. Synthesis of (+)-β-cyperone and (-)-eudesma-3,5-diene from Santonin

Article abstract of DOI:10.1016/0040-4020(96)00571-6

Santonin (1) and other sesquiterpene lactones (2-3) react with pyrrolidine and other cyclic secondary amines to afford γ-hydroxyamides, which by elimination with mesyl chloride in pyridine-benzene at 80°C give unsaturated amides 4a-4c, 5a-5c and 6. Starting from amides 5a-5c a series of bioactive compounds against Locusta migratoria have been prepared, differing in the oxidation states of the C-3 and C-12 carbon atoms. Starting from amides 5a and 6 two conjugated diene eudesmanes (+)-β-cyperone (15) and (-)eudesma-3,5-diene (19) have been prepared involving an elaboration of the amide group of the side chain of the eudesmane skeleton.