Cyclometalated Palladium NHC Complexes Bearing PEG Chains for Suzuki–Miyaura Cross-Coupling in Water

Abstract

We present the synthesis and characterization of four new polyethylene glycol (PEG) substituted palladium complexes bearing a cyclometalated 2-phenylimidazole ligand and an N-heterocyclic carbene (NHC) ligand. A solid-state structure reveals the chelating binding mode and the coiling of the PEG chain in the auxiliary ligand. The PEG substitution significantly increased the solubility of the complexes in several solvents, enabling the efficient Suzuki−Miyaura crosscoupling reaction of aryl chlorides in an aqueous medium. Under optimized reaction conditions, sterically demanding biphenyl compounds with up to three ortho substituents were accessible in good to excellent yields.

1-Butyl-3-methyl-2-(diphenylphosphino)imidazalolium hexafluorophosphate as an efficient ligand for recoverable palladium-catalyzed Suzuki-Miyaura reaction in neat water

“…In spite of abundant reports on performing the Suzuki-Miyaura coupling reactions, developments to improve it are currently done. For example, conducting the Suzuki-Miyaura coupling reaction in environmentally friendly solvents such as water have particular importance [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Water is a great alternative to organic solvents which disposal is a main problem in the industry.…”

Ligand Steric Effects of α-Diimine Nickel(II) and Palladium(II) Complexes in the Suzuki–Miyaura Cross-Coupling Reaction

“…The decrease in yields in the presence of excess base has been previously observed in both Ni and Pd catalytic systems. 50 , 84 The next seven experiments are dedicated to Ni A and target the variation in the concentration of boronic acid and the complex along with the influence of reaction time. Although the increased ratio of boronic acid did not increase the yield, an increased amount of Ni A having 0.3 mol % afforded a higher yield (entry 8, Table 3 ).…”

Yeni Morfolinoetil-Sübstitüyeli (NHC)PdBr2(3-Kloropiridin) Kompleksleri: Sentez, Karakterizasyon ve Suzuki-Miyaura Reaksiyonundaki Katalitik Aktivite

“…Fenil boronik asidin kullanıldığı katalitik deneylerde, ürün dönüşümleri % 81 ile % 98 arasında, 4tert butil fenil boronik asidin kullanıldığı katalitik deneylerde ise ürün dönüşümleri % 74 ile % 95 arasında gözlendi (Tablo 1-2 Bu çalışmada elde edilen sonuçlar, son zamanlarda çalışma grubumuz tarafından yayınlanan benzer bir çalışma ile karşılaştırıldığında katalizörlerin aktif oldukları gözlendi [19]. Başka bir çalışmada PEG zincirlerine bağlanan Pd(II)NHC komplekslerinin su / etilalkol çözücü karışımı içerisinde 24 saatteki katalitik aktivitesi ile karşılaştırıldığında yaklaşık katalitik dönüşümlerin elde edildiği görüldü [29]. Ayrıca, benzer bir çalışmada katalizör olarak manyetik nanopartikül destekli Pd(II)NHC kompleksleri, su / etilalkol çözücü ortamında daha kolay çapraz-eşleşme reaksiyonu veren aril bromürlerin biaril ürünlerine dönüşümleri 1 saat süre ile denenmiş ve yaklaşık sonuçlar elde edilmiştir [30].…”