DEVELOPMENT OF THE JULIA ASYMMETRIC EPOXIDATION REACTION .2. APPLICATION OF THE OXIDATION TO ALKYL ENONES, ENEDIONES AND UNSATURATED KETO ESTERS

Polyleucine-based systems have been used to catalyse the asymmetric ox idation of a variety of alkyl enones 1-4,9-14, an enynone 16 and a die none 17 to afford the corresponding epoxides 5-8, 18-26 in good to exc ellent yield and optical purity. A range of enediones 30-32, 34 and on e unsaturated keto ester 33 have also been epoxidised stereoselectivel y to afford optically active epoxides 35-39. The epoxidations were car ried out with basic peroxide as the oxidant; the polyleucine catalyst was prepared from leucine N-carboxyanhydride using 1,3-diaminopropane, water (employing a humidity cabinet) or a polystyrene immobilised ami ne as the initiator. Preliminary mass spectral data on material derive d from L-leucine and 1,3-diaminopropane (DAP-PLL) suggest that the cat alyst consists of material that contains 22 +/- 10 leucine residues.