title: Direct asymmetric aldol reactions inspired by two types of natural aldolases: water-compatible organocatalysts and Zn(II) complexes.
abstract: In this article the utility of water-compatible amino-acid-based catalysts was explored in the development of diastereo- and enantioselective direct aldol reactions of a broad range of substrates. Chiral C(2)-symmetrical proline- and valine-based amides and their Zn(II) complexes were designed for use as efficient and flexible chiral catalysts for enantioselective aldol reactions in water, on water, and in the presence of water. The presence of 5 mol % of the prolinamide-based catalyst affords asymmetric intermolecular aldol reactions between unmodified ketones and various aldehydes to give anti products with excellent enantioselectivities. We also demonstrate aldol reactions of more demanding substrates with high affinity to water (i.e., acetone and formaldehyde). Newly designed serine-based organocatalyst promoted aldol reaction of hydroxyacetone leading to syn-diols. For presented catalytic systems organic solvent-free conditions are also acceptable, making the elaborated methodology interesting from a green chemistry perspectives.
authors.affiliation: Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Paradowska
authors.forename: Monika
authors.initials: M
authors.lastname: Pasternak
authors.forename: Bartosz
authors.initials: B
authors.lastname: Gut
authors.forename: Beata
authors.initials: B
authors.lastname: Gryzło
authors.forename: Jacek
authors.initials: J
authors.lastname: Mlynarski
mesh_terms: D000446:Aldehyde-Lyases / Q000737:chemistry*; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D014867:Water / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D014867:Water; D000446:Aldehyde-Lyases; D015032:Zinc