Search

The stereoselective reaction of α‐amido‐substituted malonic acid half oxyesters (α‐amido‐MAHOs) with isatins was developed. A cinchona alkaloid thiourea catalyst gave products bearing a tetrasubstituted stereogenic centre in high yields with high diastereo‐ and enantioselectivities (75–99% yield, 83:17–97:3 dr, 92:8–99:1 er). The obtained products can be converted into some chiral compounds without loss of enantiopurity. Density functional theory (DFT) calculations were conducted to clarify the origin of stereoselectivities, and suggested that the first stereogenic centre is set in the decarboxylation, the second in the protonation. [ABSTRACT FROM AUTHOR]

We report the enantiodivergent reaction of ketimines derived from α‐ketoesters with malononitriles using a single chiral source. The reactions using an 8‐quinolinesulfonyl cinchona alkaloid catalyst in the presence and absence of Et2Zn gave both enantiomers in high yields with high enantioselectivities (53∼99% yield, 99:1∼3:97 er). The obtained malononitrile‐derived α‐amino acids were converted into various optically active compounds. A reaction mechanism is proposed to explain the observed enantiodivergency. [ABSTRACT FROM AUTHOR]

The enantioselective synthesis of chiral N,N‐acetals derived from α‐dicarbonyl compounds has been achieved. Good yields and enantioselectivities were observed for the reaction with various α‐dicarbonyl compounds with 2‐aminobenzamides using chiral bis(imidazoline)‐phosphoric acid catalysts. Based on these experimental investigations, a possible transition state is proposed to explain the origin of the asymmetric induction. [ABSTRACT FROM AUTHOR]

We disclose herein an efficient enantioselective conjugate addition reaction between coumarin-3-carboxylic acids and malonic acid half thioesters (MAHTs). The reaction was catalyzed by N-heteroarenesulfonyl Cinchona alkaloid amides to afford double-decarboxylative conjugate addition products in good yield with high enantioselectivity. The reaction of various coumarin-3-carboxylic acids with MAHTs gave products in high yield with high enantioselectivity. [ABSTRACT FROM AUTHOR]