title: New Enantiomerically Pure Alkylimido Mo-Based Complexes. Synthesis, Characterization, and Activity as Chiral Olefin Metathesis Catalysts.
abstract: Molybdenum olefin metathesis catalysts that contain aliphatic 1-phenylcyclohexylimido (NPhCy) and 2-phenyl-2-adamantylimido (NPhAd) groups and (S)-Biphen or (R)-Trip)(THF) ligands (Biphen = 3,3'-di-tert-butyl-5,5',6,6'-tetramethyl-1,1'-biphenyl-2,2'-diolate; Trip = 3,3'-bis(2,4,6-triisopropylphenyl)-2,2'-binaphtholate) have been prepared. Their catalytic activity and enantioselectivity in desymmetrization reactions such as ring-closing metathesis of amines and lactams and ring-opening/cross-metathesis of substituted norborneols with styrene were compared to the results obtained with the only known alkylimido catalyst Mo(NAd)(CHCMe(2)Ph)[(S)-Biphen]. The activities and enantioselectivities provided by these new chiral complexes vary significantly, but in virtually all instances explored were not superior to the adamantylimido analogs.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
authors.forename: Tatiana S
authors.initials: TS
authors.lastname: Pilyugina
authors.forename: Richard R
authors.initials: RR
authors.lastname: Schrock
authors.forename: Peter
authors.initials: P
authors.lastname: Müller
authors.forename: Amir H
authors.initials: AH
authors.lastname: Hoveyda