title: Enantioconvergent cross-couplings of racemic alkylmetal reagents with unactivated secondary alkyl electrophiles: catalytic asymmetric Negishi α-alkylations of N-Boc-pyrrolidine.
abstract: Although enantioconvergent alkyl-alkyl couplings of racemic electrophiles have been developed, there have been no reports of the corresponding reactions of racemic nucleophiles. Herein we describe Negishi cross-couplings of racemic α-zincated N-Boc-pyrrolidine with unactivated secondary halides, thus providing a one-pot, catalytic asymmetric method for the synthesis of a range of 2-alkylpyrrolidines (an important family of target molecules) from N-Boc-pyrrolidine, a commercially available precursor. Preliminary mechanistic studies indicated that two of the most straightforward mechanisms for enantioconvergence (dynamic kinetic resolution of the organometallic coupling partner and a simple β-hydride elimination/β-migratory insertion pathway) are unlikely to be operative.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Cordier
authors.forename: Rylan J
authors.initials: RJ
authors.lastname: Lundgren
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Fu
mesh_terms: D000478:Alkylation; D002384:Catalysis; D007202:Indicators and Reagents / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D007202:Indicators and Reagents; D009942:Organometallic Compounds; D011759:Pyrrolidines; C032519:pyrrolidine