title: A new class of substituted aryl bis(oxazoline) ligands for highly enantioselective copper-catalyzed asymmetric aldol addition of dienolsilane to pyruvate and glyoxylate esters.
abstract: [reaction: see text] A new class of bis(oxazoline) ligands are introduced that feature o-alkoxyaryl substituents and provide the highest enantioselectivities yet reported for the copper-catalyzed asymmetric dienosilane aldol addition to pyruvate and glyoxylate esters. Enantioselectivities up to 98% ee (before recrystallization) and isolated yields up to 91% were observed. Additionally, chloride counterions were found to be superior to triflate for this reaction.
authors.affiliation: The Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Julie Cong-Dung
authors.initials: JC
authors.lastname: Le
authors.forename: Brian L
authors.initials: BL
authors.lastname: Pagenkopf
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D002712:Chlorides / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D004952:Esters / Q000737:chemistry; D006038:Glyoxylates / Q000737:chemistry; D006841:Hydrocarbons, Aromatic / Q000737:chemistry; D008024:Ligands; D008698:Mesylates / Q000737:chemistry; D015394:Molecular Structure; D010080:Oxazoles / Q000138:chemical synthesis*; D011773:Pyruvates / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D002712:Chlorides; D004952:Esters; D006038:Glyoxylates; D006841:Hydrocarbons, Aromatic; D008024:Ligands; D008698:Mesylates; D010080:Oxazoles; D011773:Pyruvates; D012821:Silanes; D003300:Copper; C116609:3-hydroxybutanal; C012077:trifluoromethanesulfonic acid; C031150:glyoxylic acid