PHOTODECONJUGAISON ENANTIOSELECTIVE D'ESTERS ET DE LACTONES CONJUGUEES EN PRESENCE D'EPHEDRINE

Article abstract of DOI:10.1016/S0040-4020(01)85129-2

α,β-unsaturated esters and α-alkylidene lactones bearing one γ-hydrogen on the unsaturated chain, were deconjugated by irradiation with UV light (λ=254 nm).When the reaction was carried out in the presence of (+) or (-) ephedrine, an enantioselective C-protonation of the photodienolic intermediate led to the deconjugated ester with an enantiomeric excess up to 30 percent.The scape of the reaction and the configuration of the new asymmetric center are discussed.