title: Catalytic enantioselective cross-couplings of secondary alkyl electrophiles with secondary alkylmetal nucleophiles: Negishi reactions of racemic benzylic bromides with achiral alkylzinc reagents.
abstract: We have developed a nickel-catalyzed method for the asymmetric cross-coupling of secondary electrophiles with secondary nucleophiles, specifically, stereoconvergent Negishi reactions of racemic benzylic bromides with achiral cycloalkylzinc reagents. In contrast to most previous studies of enantioselective Negishi cross-couplings, tridentate pybox ligands are ineffective in this process; however, a new, readily available bidentate isoquinoline-oxazoline ligand furnishes excellent ee's and good yields. The use of acyclic alkylzinc reagents as coupling partners led to the discovery of a highly unusual isomerization that generates a significant quantity of a branched cross-coupling product from an unbranched nucleophile.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Jörg T
authors.initials: JT
authors.lastname: Binder
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Cordier
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Fu
mesh_terms: D002384:Catalysis; D006842:Hydrocarbons, Brominated / Q000737:chemistry*; D007546:Isoquinolines / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010080:Oxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
chemical_list: D006842:Hydrocarbons, Brominated; D007546:Isoquinolines; D009942:Organometallic Compounds; D010080:Oxazoles; D009532:Nickel; D015032:Zinc; C039109:isoquinoline