Hypervalent Iodine(III)-Mediated Oxidative C-H Amination of Phenols and Anilines with Azoles
Koji Morimoto1,2, Kana Yanase1, Toshifumi Dohi1,2
1College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan.
Abstract:
We report a hypervalent iodine-mediated C-N cross-coupling between phenols or anilines and azoles. A catalytic variant based on in situ oxidation of an aryl iodide was also developed. The reaction proceeds at room temperature in an HFIP/CH3NO2 solvent system and avoids the use of prefunctionalized aryl halides as coupling partners. Under optimized conditions, triazoles, pyrazoles, and other azoles couple in up to 90% isolated yield with broad functional-group tolerance. The HFIP/CH3NO2 mixture (3:1) suppresses competitive O-N coupling and promotes selective C-N bond formation. A catalytic variant using an aryl iodide (10 mol %) with mCPBA and CF3COOH as the terminal oxidant-acid pair delivers comparable efficiency. This operationally simple protocol complements palladium- or copper-catalyzed methods by eliminating aryl-halide preactivation and transition metals.
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