An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode

Abstract

<jats:p>In this article we describe an enantioselective hydroxylation of benzylic C-H bonds with a unique activation mechanism. A chiral aryl iodide catalyst initially acts as precursor for a brominating reagent which subsequently brominates the benzylic C-H bond in a non-stereoselective fashion through a radical bromination. In the second step of this transofrmation, the same catalyst acts as a chiral ligand in a Cu-catalyzed enantioconvergent substitution. We present a broad substrate scope and an intial mechanistic proposal based on a plethora of control experiments.&lt;br&gt;</jats:p>

Ensemble Effects of Explicit Solvation on Allylic Oxidation

“…15 By allowing a Cu(II)-superoxide complex to react with acyl chloride substrates, Pirovano and co-workers have found the resultant complex to be a reactive nucleophile, which could be subsequently be employed for the Baeyer-Villiger oxidations of aldehydes. 16 More recently, C-H bond activation of methylene groups has been achieved using a triazole based ligand and mCPBA, 17 and a bioinspired Cu(II) complex was used in the hydroxylation of benzene under mild conditions. 18 With the aim of developing new, economically advantageous catalysts having increased sustainability for allylic oxidations, Wu and co-workers 19 developed a Cu(II) 2-quinoxalinol salen complex which affected the oxidation of allylic species without the common additional requirements of high heat or long reaction times.…”