Neopentylglycolborylation of ortho-substituted aryl halides catalyzed by NiCl(2)-based mixed-ligand systems.
NiCl(2)-based mixed-ligand systems were shown to be very effective catalysts for the neopentylglycolborylation of aryl iodides, bromides, and chlorides bearing electron-rich and electron-deficient ortho-substituents. Although NiCl(2)-based single-ligand catalytic systems were able to mediate neopentylglycolborylation of selected substrates, they were not as effective for all substrates, highlighting the value of the mixed-ligand concept. Optimization of the Ni(II)-catalyzed neopentylglycolborylation of 2-iodoanisole and methyl 2-iodobenzoate demonstrated that, while the role of ligand and coligand in the conversion of Ni(II) precatalyst to Ni(0) active catalyst cannot be ignored, a mixed-ligand complex is likely present throughout the catalytic cycle. In addition, protodeborylation and hydrodehalogenation were demonstrated to be the predominant side reactions of Ni(II)-catalyzed borylation of ortho-substituted aryl halides containing the electron-deficient carboxylate substituents. Ni(II) complexes in the presence of H(2)O and Ni(0) are responsible for the catalysis of these side reactions.
Moldoveanu
Costel
C
Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
Wilson
Daniela A
DA
Wilson
Christopher J
CJ
Leowanawat
Pawaret
P
Resmerita
Ana-Maria
AM
Liu
Chi
C
Rosen
Brad M
BM
Percec
Virgil
V
D001897:Boronic Acids / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism
D001897:Boronic Acids; D006843:Hydrocarbons, Chlorinated; D008024:Ligands; D009942:Organometallic Compounds; C022838:nickel chloride; D009532:Nickel