Computational and experimental evidence for Sb(v) metal mediated C-H activation and oxidative functionalization of
Anjaneyulu Koppaka1, Shu-Sen Chen1, Dongdong Yang1
1Department of Chemistry and Biochemistry, Brigham Young University Provo Utah 84604 USA Anjaneyulu.Koppaka@byu.edu dhe@byu.edu.
Abstract:
Inorganic SbV complexes are one of the most well-known Lewis acids that typically indirectly activate nonpolar hydrocarbon bonds by acting as Brønsted superacids. Here we have used a combination of quantum-chemical calculations and experiments to demonstrate that inorganic SbV complexes can directly activate aromatic sp2 C-H bonds and induce oxidative functionalization to form aryl esters. C-H activation was first demonstrated by reaction of SbV(TFA)5 (TFA = trifluoroacetate) with toluene at moderate temperatures that resulted in SbV-C bond intermediates (TFA)4SbV(para-tolyl) and (TFA)3SbV(para-tolyl)2. Calculations predicted and then experiments confirmed that at a higher temperature reductive functionalization occurs to generate oxidized aryl ester products. Theory and experiment indicate that due to a Curtin-Hammet type equilibrium the initial para C-H activation regioselectivity changes to mainly ortho and meta selectivity for reductive oxy-functionalization.
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