Schiff base Cu(I) catalyst for aerobic oxidation of primary alcohols

We report here new copper(I)-Schiff base complexes for the selective oxidation of primary alcohols to aldehydes under ambient conditions (with 2,2,6,6-tetramethylpiperdine-N-oxyl (TEMPO), N-methylimidazole (NMI), ambient air, acetonitril and RT). Particularly, the copper(I) complex bearing N-(4-fluorophenyl)-1-(furan-2-yl)methanimine (L2) showed high activity in the series and gave near- quantitative yields in the oxidations of benzyl alcohol (99% yield in 1 h) and 1-octanol (96% yield in 24 h). Based on the X-ray structure determination, the complex has a square pyramidal coordination accomplished by two L2 ligands and bromide as a counter anion. The oxidation reactions were monitored with UV vis and in situ ATR-IR spectroscopy to study the changes in the catalytic structure and to elucidate the catalytic properties and the mechanistic details. Accordingly, detachment of one of the L2 ligands from the complexes is related to the oxidation activity.