title: Enantioselective Pd(II)-catalyzed aerobic oxidative amidation of alkenes and insights into the role of electronic asymmetry in pyridine-oxazoline ligands.
abstract: Enantioselective intramolecular oxidative amidation of alkenes has been achieved using a (pyrox)Pd(II)(TFA)(2) catalyst (pyrox = pyridine-oxazoline, TFA = trifluoroacetate) and O(2) as the sole stoichiometric oxidant. The reactions proceed at room temperature in good-to-excellent yields (58-98%) and with high enantioselectivity (ee = 92-98%). Catalyst-controlled stereoselective cyclization reactions are demonstrated for a number of chiral substrates. DFT calculations suggest that the electronic asymmetry of the pyrox ligand synergizes with steric asymmetry to control the stereochemical outcome of the key amidopalladation step.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
authors.forename: Richard I
authors.initials: RI
authors.lastname: McDonald
authors.forename: Paul B
authors.initials: PB
authors.lastname: White
authors.forename: Adam B
authors.initials: AB
authors.lastname: Weinstein
authors.forename: Chun Pong
authors.initials: CP
authors.lastname: Tam
authors.forename: Shannon S
authors.initials: SS
authors.lastname: Stahl
mesh_terms: D000475:Alkenes / Q000737:chemistry; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D003500:Cyclization; D008024:Ligands; D015394:Molecular Structure; D010080:Oxazoles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D008024:Ligands; D010080:Oxazoles; D011725:Pyridines; D010165:Palladium