Ligand mediated iron catalyzed dimerization of terminal aryl alkynes: scope and limitations

Regioselective dimerization of terminal aryl alkynes to produce conjugated enynes has been achieved using FeCl3 and KOtBu in the presence of either DMEDA or dppe

Ganesh Chandra Midya; Bibudha Parasar; Kalyan Dhara; Jyotirmayee Dash

2014

Key concepts

Scholarcy highlights

  • Regioselective dimerization of terminal aryl alkynes to produce conjugated enynes has been achieved using FeCl3 and KOtBu in the presence of either DMEDA or dppe
  • The reaction proceeds smoothly in toluene at 145 °C for 2 h to give the corresponding head-to-head dimers in good to excellent yields with high E-selectivity. Both strongly electron-donating and electron-withdrawing groups are compatible with this procedure
  • The aliphatic acetylene fails to react under this catalytic system which suggests that potassium tertiary butoxide activates the conjugated system of aryl acetylene through cation–pi interaction and pi–pi interaction
  • Mechanistic pathways for both FeCl3 catalyzed dimerization of aryl alkynes and FeCl2 catalyzed dimerization of phenyl acetylene have been proposed

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