Using the knowledge previously gained from the mechanistic understanding of how copper (I) and O2 oxidize gamma sp3 C-H bonds of steroidal substrates, efforts are being made in understanding systems that have a more challenging C-H bond to functionalize, β sp2 C-H bonds. With our synthetic strategy three specific features of our system are able to change which allow us to control the stereoselective properties of the Cu/O2 cores which enables us to better understand the reactivity of our systems (ketone, amine, and oxidant). By changing the substrate’s structure in our method, it aids in understanding not only this synthetic system, but also the metalloenzymes that use copper to carry out C-H bond hydroxylation (e.g. PHM and DβH) and for applying these methodologies for more synthetic and industrial purposes. Current developments for sp2 C-H bond hydroxylation include using a palladium center for ortho-CH bond oxygenation of aromatic systems, as well as catalysts using rhodium and ruthenium have shown to be effective site-selective hydroxylation transition metal catalysts, while copper has been a lesser explored transition metal in this area. However, one noticeable development that uses copper is the direct hydroxylation can occur via deprotonative cupration with high yields and with an array of substrates, but the directing group is unable to detach from the original substrate. In this research presentation, we describe our recent findings on the intramolecular hydroxylation of various substrate-ligands containing sp2 and sp3 C-H bonds, as well as a mechanistic understanding for a proposed reaction pathway for the sp2 systems. By isolating steps in the reaction, we have been able to characterize and propose an LCu(II)-OOH species responsible for the β-hydroxylation of our sp2 systems.

Cu - directed hydroxylation of sp2 C-H bonds

256th National Meeting (2018)

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