Asymmetric catalysis by chiral hydrogen-bond donors

Electrostatic repulsion as an additional selectivity factor in asymmetric proline catalysis

The metal free, single amino acid-catalyzed asymmetric desymmetrization (ADS) of meso-compounds with nitrosobenzene has been investigated using DFT. In this communication, we describe the role of electrostatic and dipole-dipole interactions in amino acid-catalyzed reactions, which has not previously been invoked in discussions of these important reactions.

Hydrophobic amplification of noncovalent organocatalysis

The effects of hydrogen-bonding organocatalysts and water for the acceleration of epoxide openings with a variety of nucleophiles are additive and lead to excellent yields of the catalyzed reactions in water.

Parallel sheet structure in cyclopropane γ-peptides stabilized by C–H⋯O hydrogen bonds

A three-residue trans-cyclopropane gamma-peptide adopts an infinite parallel sheet structure in the solid state stabilized by intermolecular C-H...O hydrogen bonds, as demonstrated by single crystal X-ray diffraction.

Structural optimization of thiourea-based bifunctional organocatalysts for the highly enantioselective dynamic kinetic resolution of azlactones

This article describes the synthesis of a library of structurally diverse bifunctional organocatalysts bearing both a quasi-Lewis acidic (thio)urea moiety and a Brønsted basic tertiary amine group. Sequential modification of the modular catalyst structure and subsequent screening of the compounds in the alcoholytic dynamic kinetic resolution (DKR) of azlactones revealed valuable structure-activity relationships. In particular, a "hit-structure" was identified which provides e.g.N-benzoyl-tert-leucine allyl ester in an excellent enantiomeric excess of 95%.