Efficient Synthesis of Substituted 3-Amino-3,4-dihydropyran-2-ones Diastereo and Enantioselective Tandem Michael Addition and Lactonization between α,β-Unsaturated Ketones and Glycine-Derived Silyl Enolates Using a Chiral Quaternary Ammonium Phenoxide

Chiral quaternary ammonium phenoxides are readily prepared from commercially available cinchona alkaloids and are employed as useful new asymmetric organocatalysts.The cinchonidine-derived catalyst is highly effective on Michael addition and successive lactonization between glycine-derived silyl enolates and α,β-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.