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Toward a Protecting-Group-Free Halogen−Metal Exchange Reaction: Practical, Chemoselective Metalation of Functionalized Aromatic Halides Using Dianion-type Zincate, t Bu 4 ZnLi 2

2006; American Chemical Society; Volume: 128; Issue: 26 Linguagem: Inglês

10.1021/ja058246x

1943-2984

Masanobu Uchiyama, Taniyuki Furuyama, Minoru Kobayashi, Yotaro Matsumoto, Kentaro Tanaka,

Catalytic Cross-Coupling Reactions

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.