Synthesis of Hydrophilic Phosphorus Ligands and Their Application in Aqueous‐Phase Metal‐Catalyzed Reactions

Abstract

Transition metal‐catalyzed reactions in aqueous media are experiencing a constant increase in interest. In homogenous catalysis the use of water as a solvent offers advantages in cost, safety, the possibility of two‐phase catalysis and simplified separation strategies. In the life sciences, transition metal catalysis in aqueous systems enables the ligation or modification of biopolymers in buffer systems or even in their cellular environment. In biocatalysis, aqueous systems allow the simultaneous use of enzymes and transition metal catalysts in cascade reactions. The use of water‐soluble phosphine ligands still represents the most reliable and popular strategy for transferring metal catalysts into the aqueous phase. This review summarizes the recent advancements in this field since 2009 and describes current synthetic strategies for the preparation of hydrophilic phosphines and phosphites. In addition, recent applications of transition metal catalysis in aqueous solvents using these hydrophilic ligands are presented.

Frustrated and Realized Hydrogen Bonding in 4-Hydroxy-3,5-ditertbutylphenylphosphine Derivatives

“…5 An important theme over the past decades has been on triarylphosphines with substituents that can support even aqueous solubility of neutral metal complexes of such phosphines and facilitating catalysis in water. 6 Phenolic phosphines such as Ph 2 PC 6 H 4 OH have been used either natively or with chain extenders such as triethylene glycol to enhance solubility for a ruthenium complex for catalysis in water. 7 The confinement of triarylphosphines in microenvironments leading to enhanced performance of catalytic processes 8 as well as a number of studies aimed at enhanced anticancer activity also of ruthenium complexes 9−13 have been reported.…”

Hyperbranched polymer immobilized palladium nanoparticles as an efficient and reusable catalyst for cyanation of aryl halides and reduction of nitroarenes

“…Column chromatography was carried out on silica gel 60 Merck (230-240 mesh) in a 2 cm diameter column. 1 H NMR and 13 C NMR spectra were recorded at 400 MHz and 100 MHz, respectively on Bruker Avance HD. Chemical shifts are given on the δ-scale in ppm, and residual solvent peaks were used as internal standards.…”

“…Different ligands and functional groups especially phosphorus and nitrogenous ligands were used for preparation of the various heterogeneous catalysts. However, compared to phosphorus ligands which are usually toxic, expensive and thermally unstable, less toxic, cheap and easily synthesis nitrogenous ligands are more attractive [1][2][3].…”

Sterically Crowded Tris(2‐(trimethylsilyl)phenyl)phosphine – Is it Still a Ligand?

“…[11] On smaller scale syntheses a wide range of tailored phosphines is used as ligands in a variety of reactions ranging from asymmetric hydrogenation to cross coupling reactions. [12][13][14][15] The activity, selectivity and stability of the catalyst complexes is dictated by both the electronic structure of the phosphine as well as the steric demand and repulsion exerted onto the substrate. [16][17][18][19][20] PCy 3 for example is an excellent ligand in Sonogashira coupling reactions as the high steric demand of the cyclohexyl groups favours the formation of Pd 0 species with low coordination numbers facilitating oxidative addition.…”

“…Besides their use in hydroformylation [9,10] a range of multi‐ton processes incorporates phosphines to stabilise transition metals [11] . On smaller scale syntheses a wide range of tailored phosphines is used as ligands in a variety of reactions ranging from asymmetric hydrogenation to cross coupling reactions [12–15] . The activity, selectivity and stability of the catalyst complexes is dictated by both the electronic structure of the phosphine as well as the steric demand and repulsion exerted onto the substrate [16–20] …”