Asymmetric petasis reactions catalyzed by chiral biphenols.
Chiral biphenols catalyze the enantioselective Petasis reaction of alkenyl boronates, secondary amines, and ethyl glyoxylate. The reaction requires the use of 15 mol % of (S)-VAPOL as the catalyst, alkenyl boronates as nucleophiles, ethyl glyoxylate as the aldehyde component, and 3 A molecular sieves as an additive. The chiral alpha-amino ester products are obtained in good yields (71-92%) and high enantiomeric ratios (89:11-98:2). Mechanistic investigations indicate single ligand exchange of acyclic boronate with VAPOL and tetracoordinate boronate intermediates.
Lou
Sha
S
Department of Chemistry, Center for Chemical Methodology and Library Development, Boston University, 24 Cummington Street, Boston, Massachusetts 02215, USA.
Schaus
Scott E
SE
D000588:Amines / Q000737:chemistry*; D000596:Amino Acids / Q000138:chemical synthesis*; D001897:Boronic Acids / Q000737:chemistry*; D002384:Catalysis; D006038:Glyoxylates / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010616:Phenanthrenes / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism
D000588:Amines; D000596:Amino Acids; D001897:Boronic Acids; D006038:Glyoxylates; D010616:Phenanthrenes; D010636:Phenols; C510253:VAPOL ligand; C031150:glyoxylic acid