Chemistry Letters, Vol.35, No.8, 916-917, 2006
Diastereo- and enantioselective tandem Michael addition and lactonization catalyzed by chiral quaternary ammonium phenoxide: Stereoselective synthesis of the two enantiomers by using a single chiral source
Diastereo- and enantio-selective synthesis of 3,4-dihydropyran-2-ones from various silyl enolates and alpha,beta-unsaturated ketones were successfully carried out by using cinchonidine-derived quaternary ammonium phenoxide. In this reaction, a synthesis of the two enantiomers was achieved by an appropriate choice of a substituent on the bridgehead nitrogen of cinchonidine.