Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands
AbstractTriethylammonium salts of phosphinoferrocene amidosulfonates with electron-rich dialkyphosphino substituents, R2PfcCONHCH2SO3(HNEt3) (4a–c), where fc = ferrocene-1,1′-diyl, and R = i-Pr (a), cyclohexyl (Cy; b), and t-butyl (c), were synthesized from the corresponding phosphinocarboxylic acids-borane adducts, R2PfcCO2H·BH3 (1a–c), via esters R2PfcCO2C6F5·BH3 (2a–c) and adducts R2PfcCONHCH2SO3(HNEt3)·BH3 (3a–c). Compound 4b was shown to react with [Pd(μ-Cl)(η-C3H5)]2 and AgClO4 to afford the zwitterionic complex [Pd(η3-C3H5)(Cy2PfcCONHCH2SO3-κ2O,P)] (5b), in which the amidosulfonate ligand coordinates as a chelating donor making use of its phosphine moiety and amide oxygen. The structures of 3b·CH2Cl2, 4b and 5b·CH2Cl2 were determined by single-crystal X-ray diffraction analysis. Compounds 4a–c and their known diphenylphosphino analogue, Ph2PfcCONHCH2SO3(HNEt3) (4d), were studied as supporting ligands in Pd-catalyzed cyanation of aryl bromides with K4[Fe(CN)6] and in Suzuki–Miyaura biaryl cross-coupling performed in aqueous reaction media under mild reaction conditions. In the former reaction, the best results were achieved with a catalyst generated from [PdCl2(cod)] (cod = η2:η2-cycloocta-1,5-diene) and 2 equiv. of the least electron-rich ligand 4d in dioxane–water as a solvent. In contrast, the biaryl coupling was advantageously performed with a catalyst resulting from palladium(II) acetate and ligand 4a (1 equiv.) in the same solvent. View Full-Text
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Schulz, J.; Horký, F.; Císařová, I.; Štěpnička, P. Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands. Catalysts 2017, 7, 167.
Schulz J, Horký F, Císařová I, Štěpnička P. Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands. Catalysts. 2017; 7(6):167.Chicago/Turabian Style
Schulz, Jiří; Horký, Filip; Císařová, Ivana; Štěpnička, Petr. 2017. "Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands." Catalysts 7, no. 6: 167.
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