Iron-Catalyzed Cross-Coupling of <i>Bis</i>-(aryl)manganese Nucleophiles with Alkenyl Halides: Optimization and Mechanistic Investigations

Abstract

Various substituted bis-(aryl)manganese species were prepared from aryl bromides by one-pot insertion of magnesium turnings in the presence of LiCl and in situ trans-metalation with MnCl2 in THF at −5 °C within 2 h. These bis-(aryl)manganese reagents undergo smooth iron-catalyzed cross-couplings using 10 mol% Fe(acac)3 with various functionalized alkenyl iodides and bromides in 1 h at 25 °C. The aryl-alkenyl cross-coupling reaction mechanism was thoroughly investigated through paramagnetic 1H-NMR, which identified the key role of tris-coordinated ate-iron(II) species in the catalytic process.

Keywords

• iron catalysis
• cross-coupling
• <i>bis</i>-(aryl)manganese
• alkenyl halides
• <i>ate</i> iron(ii) complex