Diastereo- and Enantioselective Synthesis of 3-Amino-3,4-dihydropyran-2-ones by Tandem Michael Addition and Lactonization Using a Chiral Quaternary Ammonium Phenoxide

The first efficient synthesis of 3-amino-3,4-dihydropyran-2-ones from glycine-derived silyl enolates and α,β-unsaturated ketones was successfully performed by using quaternary ammonium phenoxide prepared from cinchonidine. In this asymmetric reaction, the corresponding 3-amino-3,4-dihydropyran-2-ones were obtained in high yields with complete diastereoselectivities and good to excellent enantioselectivities.