Palladium-Catalyzed Suzuki-Miyaura Cross-Coupling of α-Halo-methyl Oxime Ethers and Site-Selective Cross-Coupling of Dihalo Derivatives

摘要

The cross-coupling reaction of chloro- and bromomethyl oxime ethers with a wide range of aryl-, heteroaryl- and vinylboronic acids in the presence of catalytic palladium complexes with different phosphines has been carried out with good yields (60-98%, 40 examples). Regioselective cross-coupling reactions differentiating between an alkyl or aryl position are achieved from dihalo oxime ethers containing Csp~2- and Csp~3-halogen bonds using mono- or dicoordinated palladium catalysts such as Pd(dba)2/P(o-tolyl)3 or Pd(PPh3)4. The selective or- thogonal functionalization of dihalo oxime ethers is also described. Site-selective transformations allow the introduction of the biaryl motif into dihalo oxime ethers preserving the highly activated alkyl halide moiety vicinal to the oxime group for further transformations. In this context, Z- and E-oxime ethers could be considered as synthetic equivalents of ketones in palladium-catalyzed Suzuki reactions.