An Iron-Based Dehydration Catalyst for Selective Formation of Styrene

Abstract

We report the synthesis and crystal structure of [Fe(OTf)2(FOX)] (A). This robust iron(II) complex was successfully applied as a homogeneous catalyst for the dehydration of 1-phenylethanol to styrene. Even at low catalyst loadings and moderate reaction temperatures,A showed a high catalytic efficiency. It was found to selectively activate the benzylic alcohol group of 1-phenylethanol. This is challenging since the vinyl system of styrene is highly reactive. In contrast to most of the other dehydration processes, the use of a Brønsted acid was not necessary. Furthermore, mechanistic insights into this E1-type transformation and its competing SN1-type side reactions are reported. [Fe(cHexOH)(OTf)(FOX)][OTf] (B), an alcohol adduct ofA, [Fe(H2O)2(FOX)][OTf]2(C), the completely hydrated derivative ofA, and [μ-O{Fe(OTf)(FOX)}2][OTf]2(D), a dinuclear oxidation product ofA, were also characterized and are discussed.