CuI/N4 ligand/TEMPO derivatives: A mild and highly efficient system for aerobic oxidation of primary alcohols

A new system consisting of a copper(I) complex generated in situ from a tetradentate nitrogen ligand and CuI in combination with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives was successfully developed. The system was suitable for efficient and selective aerobic oxidation of primary benzyl and allyl alcohols with a wide range of functional groups to the corresponding aldehydes at room temperature. The best result was obtained with N,N’-dimethyl-N,N’-bis(2-pyridylmethyl)ethane-1,2-diamine as the ligand and 4-OH-TEMPO as a cocatalyst in CH3CN. In addition, high-resolution mass spectrometry, ultraviolet-visible spectroscopy, and electrochemical experiments were used to provide evidence of intermediates.

Graphical AbstractA copper(I) complex generated in situ from N,N’-dimethyl-N,N’-bis(2-pyridylmethyl)ethane-1,2-diamine (a tetradentate nitrogen) ligand and CuI in combination with 4-OH-TEMPO catalyzed the aerobic oxidation of primary benzyl and allyl alcohols at room temperature.Figure optionsDownload full-size imageDownload as PowerPoint slide