STEREOSELECTIVITY QUESTIONS IN THE SYNTHESIS OF WIKSTROMOL

While the Davis oxaziridine reagent generally affords oxidation products based on simple steric considerations, this concept appears to have some limitations when used to design natural product synthetic strategies. Thus, an example has been found in which the observed stereoselectivity of an enolate oxidation is ''anomalous''. The system in question involves an enolate oxidation performed on a lignan butyrolactone having highly oxygenated aromatic rings. Besides establishing the course of this oxidation and confirming the proposed structure of wikstromol and related lignans, a single-crystal X-ray study on a wikstromol stereoisomer provides complementary data for comparison with the ''natural'' isomer.