Abstract
Copper(II) acetate is a frequent empirical choice of the copper source in copper(II)‐mediated redox reactions. The effect of the acetate counterion appears crucial but has not been adequately investigated. Herein, we report that copper(II) acetate catalyzes the aerobic dehydrogenation of chelating aromatic secondary amines. The chemoselectivity of acetate and chelating amines in this reaction provides a unique opportunity for a mechanistic study. The progression of this homogeneous reaction is monitored by using electron paramagnetic resonance spectroscopy, UV/Vis absorption spectroscopy, and manometry. The kinetic dependence on the amine substrate, copper(II), and acetate counterion, together with the results of kinetic isotope and substituent effect experiments, suggests that acetate acts both as a bridging ligand of a dinuclear catalytic center for mediating two‐electron transfer steps and as a base in the turnover‐limiting C–H bond‐cleavage step. Upon including 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as a surrogate base, DBU and acetate act in a complementary manner to enable a rapid, catalytic dehydrogenation reaction of a chelating secondary amine substrate. Finally, the contrasting reactivities between copper(II) acetate (promoting two‐electron transfer) and copper(II) perchlorate (promoting single‐electron transfer) underscores how a counterion could completely alter the mechanistic pathway of a copper‐mediated oxidation reaction.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
