title: Mechanistic Studies on Rhodium-Catalyzed Enantioselective Silylation of Aryl C-H Bonds.
abstract: Several classes of enantioselective silylations of C-H bonds have been reported recently, but little mechanistic data on these processes are available. We report mechanistic studies on the rhodium-catalyzed, enantioselective silylation of aryl C-H bonds. A rhodium silyl dihydride and a rhodium norbornyl complex were prepared and determined to be interconverting catalyst resting states. Kinetic isotope effects indicated that the C-H bond cleavage step is not rate-determining, but the C-H bond cleavage and C-Si bond-forming steps together influence the enantioselectivity. DFT calculations indicate that the enantioselectivity originates from unfavorable steric interactions between the substrate and the ligand in the transition state leading to the formation of the minor enantiomer.
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: Taegyo
authors.initials: T
authors.lastname: Lee
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: John F
authors.identifier: 0000-0002-4157-468X
authors.initials: JF
authors.lastname: Hartwig
mesh_terms: D002384:Catalysis; D007700:Kinetics; D015394:Molecular Structure; D017646:Organosilicon Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D017646:Organosilicon Compounds; D012238:Rhodium