SYNTHETIC MODULATION OF THE PERIPHERAL 2-OXYGENATION, 3-OXYGENATION, 9-OXYGENATION AND 12-OXYGENATION PATTERN OF ROTENOIDS

Synthetic modulations of the rotenoid munduserone, in terms of the peripheral oxygenation pattern, have been carried out for structure-activity purposes. Synthesis by propargyl Claisen rearrangement was successful in cases having 2,3-dimethoxylation in ring A (as in natural Leguminous rotenoids), but failed when this electron release was not present. Attempts to catalyse an unsuccessful case led instead to an alkylidenedihydrobenzofuranone. The rotenoid lacking 2,3-dimethoxylation was made by chromanone beta-ester synthesis, as was the parent rotenoid of the Boerhaavia (monocotyledonous) group. The rotenoid 12-carbonyl can be removed by reduction and dehydration, and the resulting stilbene, when catalytically hydrogenated, gives the cis-B/C-12-deoxy compound. When the reduction is effected by dissolving magnesium in methanol a separable mixture of cis- and trans-12-deoxyrotenoids is obtained.