Copper-Catalyzed Oxidative Amination of Benzoxazoles via C−H and C−N Bond Activation: A New Strategy for Using Tertiary Amines as Nitrogen Group Sources
method for oxidative amination of azoles with tertiary aminesviacopper-catalyzed C−H and C−Nbond activation has been developed. This protocol can be performed in the absence of external base and only requires atmospheric oxygen as oxidant. The catalyst system is very simple and efficient, which opens a new way for using tertiary amines as nitrogen group sources for C−Nbondformation reactions.
The C–H amination of electron-deficientarenes such as polyfluoroarenes and azole compounds with O-acylated hydroxylamines effectively proceeds in the presence of a copper catalyst even at room temperature to provide the corresponding anilines and aminoazoles in good yields.
A copper-catalyzed electrophilic, umpolung amination strategy for the direct C-H amination of polyfluoroarenes and 1,3-azoles has been developed. The copper-based amination reaction is robust and can be easily scaled up on a gram scale. Its application to an annulative electrophilic amination of o-alkynylphenols and -anilines for the synthesis of 3-aminobenzofurans and -indoles is also described.