EFFICIENT SYNTHESIS OF SUBSTITUTED 3-AMINO-3,4-DIHYDROPYRAN-2-ONES DIASTEREO AND ENANTIOSELECTIVE TANDEM MICHAEL ADDITION AND LACTONIZATION BETWEEN alpha,beta-UNSATURATED KETONES AND GLYCINE-DERIVED SILYL ENOLATES USING A CHIRAL QUATERNARY AMMONIUM P

摘要

Chiral quaternary ammonium phenoxides are readily prepared from commercially available cinchona alkaloids and are employed as useful new asymmetric organoeatalysts.The cinchonidine-derived catalyst is highly effective on Michael addition and successive lactonization between glycine-derived silyl enolates and alpha,beta-unsaturated ketones.According to this asymmetric reaction,the corresponding 3-amino-3,4-dihydropyran-2-ones are formed in high yields with complete diastereoselectivities and excellent enantioselectivities.