Toward a protecting-group-free halogen-metal exchange reaction: practical, chemoselective metalation of functionalized aromatic halides using dianion-type zincate, tBu4ZnLi2.
A versatile preparation method for aromatic zincate compounds through a halogen-zinc exchange reaction using dilithium tetra-tert-butylzincate (tBu4ZnLi2) has been developed. This reagent permits efficient preparation of highly functionalized aromatic zincates, particularly, those with electrophilic functional groups, such as ester, amide, alcohol, and phenol. Halogen-zinc exchange reactions followed by electrophilic trapping (with allyl bromide or benzaldehyde) proved to be a powerful tool for C-C bond formation on functionalized aromatic rings. The functionalized aromatic zincate intermediate was also found to undergo copper- and palladium-catalyzed C-C bond-forming reactions with good yields and high chemoselectivity.
Uchiyama
Masanobu
M
Graduate School of Pharmaceutical Sciencesce, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. uchiyama@mol.f.u-tokyo.ac.jp
Furuyama
Taniyuki
T
Kobayashi
Minoru
M
Matsumoto
Yotaro
Y
Tanaka
Kentaro
K
D000838:Anions / Q000737:chemistry; D001555:Benzene Derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D006219:Halogens / Q000737:chemistry*; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
D000838:Anions; D001555:Benzene Derivatives; D006219:Halogens; D006846:Hydrocarbons, Halogenated; D009942:Organometallic Compounds; D008094:Lithium; D015032:Zinc