Copper Promoted Aromatic Acyloxylation: The Formation of Aryl Esters through the Cross Coupling of Aryl Halides Via Comproportionation of Copper II Reactants

Abstract

Previous research in Prof. Barrios-Landeros lab has shown that Cu (I) acetate complexes can successfully promote the cross coupling of aryl halides with carboxylates to make aryl esters. The reaction proceeds by a sequence of steps that can be accessed at different points using different reagents. One of this entry points was the focus of this thesis work, specifically, to explore the ability of Cu (II) to comproportionate, as Cu (II) complexes are often cheaper and more stable. It was shown that Cu (II) acetate does, in fact, drive the copper- promoted acetoxylation of phenyl iodide in DMF. Product formation, as measured by gas chromatography (GC), showed yields of up to 90%. Furthermore, the change in color of the copper as it transitions between the various oxidation states during the reaction allowed for an in- depth analysis of the rate of reaction, via flow cell spectroscopy. Additionally, Cu (II) sulfate, an even cheaper alternative, was able to drive the reaction in the presence of acetate salts, though with lower yields. Phase transfer agents, such as tetrabutylammonium tetraflouroborate and hexaflourophosphate, increased the yield of the Cu (II) sulfate reactions. Ultimately, it was shown that the comproportionation of Cu (II) is a viable option for adding Cu (I) complexes into cross coupling reactions.