Synthesis of water soluble Pd‐Piperidoimidazolin‐2‐ylidene complexes and their catalytic activities in neat water

Abstract

Through the strategy of water soluble N‐heterocyclic carbene (NHC) ligand, Pd‐catalyzed reactions were developed in aqueous media. Therefore, four new piperidoimidazolinium salts (1a‐d) consisting of sulfonate (a), esther (b, c) and carboxylic acid (d) functionalities and their water‐soluble Pd‐NHC complexes (2a‐d) were synthesized. The new compounds were characterized by elemental analysis, FTIR, TGA, UV–vis and NMR spectroscopy. The catalytic activities of water soluble Pd‐NHC complexes (2a‐d) were investigated using the Suzuki‐Miyaura (S‐M) reaction and the reduction of nitroarenes. We found that the water‐soluble polar or ionic groups on piperidoimidazolin‐2‐ylidine had an effect on the catalytic activity. The water‐soluble catalyst can be recycled efficiently and reused six times with only a very slight loss of catalytic activity.

C(acyl)–C(sp2) and C(sp2)–C(sp2) Suzuki–Miyaura cross-coupling reactions using nitrile-functionalized NHC palladium complexes

“…The TGA spectrum of the complex 3c showed a band around 210 °C which is attributed to the pyridine group. 27 This band did not appear in the TGA spectrum of the nanoparticle of 3c, indicating the absence of pyridine in the nanostructure (Fig. S60 and S61 † ).…”

Linkage Isomers of Triangular Pd Metallacycles and Catalysis in Aqueous Suzuki Coupling Reaction

“…1 It is the cheapest, most abundant, safest, and environmentally friendly solvent as a chemical reaction medium, and has gained tremendous interest for applications in the field of homogeneous catalysis. 2 In the past few decades, the palladium-catalyzed cross-coupling reaction has evolved as the most powerful tool for the synthesis of complex organic molecules. Thus, the manufacturing of fine chemicals, pharmaceuticals, and natural products using cross-coupling reactions in water can greatly contribute to the field of sustainable organic synthesis.…”

“…8 Although their catalytic activities were similar to the results obtained in conventional organic solvents, air sensitivity limited their recyclability and synthetic applications. 11,12 The other hydrophilic ligands, such as Nheterocyclic carbenes 2,8,10,13 and N-donor ligands, 6,7,14 have also been employed in palladium-catalyzed cross-coupling in aqueous-phase reactions. The most efficient approach to form water-soluble complexes was first demonstrated by the Fujita group, by generating charged complexes employing neutral ligands.…”

A New Bis‐(NHC)‐P(II) Complex Supported on Magnetic Mesoporous Silica: An Efficient Pd(II) Catalyst for the Selective Buchwald‐Hartwig Monoarylation of Ammonia

“…During the past decades, several reports have been published on using thermally and air‐stable Pd‐NHC catalysts. These complexes catalyze cross‐coupling reactions, including Suzuki‐Miaura, [31] Heck, [32] Sonogashira, [33] Hiyama, [34] reduction of nitroarenes, [35] and reductive carbonylation of nitroarenes [36] . Navarro et al [37] .…”