Synthesis and Characterization of Triphenylphosphine Adducts of Ferrocene-Based Palladacycles and Their Performance in the Suzuki and Sonogashira Reactions with Bromo- and Chloroarenes

Abstract

Abstract:A new triphenylphosphine adduct of cyclopalladated ferrocenylpyridazine containing a chloride anion, 2a, has been synthesized from the reaction of the chloride-bridged palladacyclic dimer 1a with triphenylphosphine. The corresponding adducts 3a,b containing iodide anion have been readily prepared through anion exchange reactions of 2a,b with NaI in acetone. These complexes were characterized by elemental analysis, IR and 1 H-NMR. Additionally, their crystal structures have been determined by X-ray diffraction and intermolecular C-H···X (Cl, Br, I) bonds were found in the crystals. The use of these palladacycles as catalysts for the Suzuki and Sonogashira reactions was examined. The complexes 2a,b exhibited higher catalytic activity than the corresponding 3a,b in the Suzuki reaction. However, the order of activity of adducts with varying halogen anions is 3a~3b > 2a~2b in the Sonogashira reaction.

Magnetic nanoparticle‐tethered Schiff base–palladium(II): Highly active and reusable heterogeneous catalyst for Suzuki–Miyaura cross‐coupling and reduction of nitroarenes in aqueous medium at room temperature

“…Table presents a comparison of results for the SB‐Pd@MNPs nanomagnetic catalyst with those for other catalysts for the Suzuki–Miyaura cross‐coupling reaction. Comparison of the results demonstrates a better catalytic activity of SB‐Pd@MNPs nanomagnetic catalyst at room temperature in aqueous medium (EtOH–H 2 O (1:1)) for Suzuki–Miyaura cross‐coupling reactions . Some of the main benefits of the SB‐Pd@MNPs nanomagnetic catalyst are: (i) use of green solvents, (ii) short reaction times, (iii) mild reaction conditions, (iv) excellent selectivity, (v) ability to easily remove the catalyst from reaction mixture and (vi) reusability for subsequent reactions.…”

Chemicals from Alkynes with Palladium Catalysts

“…Palladacycles are palladium compounds that usually show high catalytic activity and high stability, being precursors of active PdNPs, which can act as catalysts in the copper-free Sonogashira reaction . Recent examples of their use in the copper-free Sonogashira alkynylation aryl halides are the cyclopalladated ferrocenylpyridazine palladium complex 201 , which has been used as catalyst (0.1–2 mol %) in the reaction of terminal alkynes with aryl bromides, using cesium acetate as base, in N , N -dimethylacetamide (DMA) as solvent at 120 °C . An example of the use of this methodology is the preparation of alkyne 203 from the reaction of o -bromotoluene and phenylacetylene (Scheme ).…”

“…226b Recent examples of their use in the copper-free Sonogashira alkynylation aryl halides are the cyclopalladated ferrocenylpyridazine palladium complex 201, which has been used as catalyst (0.1−2 mol %) in the reaction of terminal alkynes with aryl bromides, using cesium acetate as base, in N,N-dimethylacetamide (DMA) as solvent at 120 °C. 257 An example of the use of this methodology is the preparation of alkyne 203 from the reaction of o-bromotoluene and phenylacetylene (Scheme 80). Aryl bromides afforded high yields, although aryl chlorides gave rise to moderate yields only when bearing electron-withdrawing groups.…”