Theoretical investigation on the mechanism of FeCl₃-catalysed cross-coupling reaction of alcohols with alkenes

Abstract

The mechanism of the FeCl₃-catalysed cross-coupling reaction of alcohols with alkenes has been investigated using the density functional theory. All calculations were performed in liquid phase. The structures of intermediates and transition states are computed and analysed in detail. The calculations show that the entire catalytic cycle consists in three steps: (1) H-abstraction, (2) free-radical addition, and (3) hydrogen transfer. The rate-limiting step in the whole catalytic cycle is the hydrogen-abstraction step. Only the quartet potential surface is likely to play an essential role in this cross-coupling reaction. The alpha-C(sp³)–H bond of the phenylpropanol is cleaved in a homolytic fashion. Moreover, we justify the change of the oxidation state of iron along the overall reaction pathway on the basis of the computed natural population atomic charges and spin densities. Our calculated results are consistent with and provide a reliable interpretation for the experimental observations that suggest the cross-coupling reaction occurs through a radical mechanism.

Keywords:

• DFT
• mechanism
• iron catalysis
• C–H activation
• cross-coupling

Additional information

Funding

This work is supported by the National Basic Research Program of China (973 Program) [grant number 2012CB932800f]; the National Natural Science Foundation of China [grant number 21073075], [grant number 21303067].