Polymer anchored 3-benzoyl-1-(1-benzylpiperidin-4-yl)-2-thiopseudourea-Pd(II) complex: An efficient catalyst for the copper and solvent free Sonogashira cross-coupling reaction

An efficient copper and solvent free Sonogashira cross-coupling reaction catalyzed by polymer supported 3-benzoyl-1-(1-benzylpiperidin-4-yl)-2-thiopseudourea-Pd(II) complex 4 (PS-bpt-Pd) was reported. This inexpensive and simply synthesized heterogeneous catalyst 4 afforded excellent yields of the cross-coupling products under mild reaction conditions. We have achieved high yields for aryl iodide coupling reactions with terminal alkynes at room temperature under copper and solvent-free conditions. In addition, we also observed moderate to good yields for aryl bromides as coupling partner. This insoluble PS-bpt-Pd(II) catalyst 4 can be easily recovered by simple filtration and reused up to five times with stable catalytic activity. In addition to this, heterogeneous Pd (II) complex is even applicable on a gram scale for cross-coupling with high catalytic efficiency. (C) 2016 Elsevier B.V. All rights reserved.