Robust and reusable supported palladium catalysts for cross-coupling reactions in flow

Chemical reaction engineering, process design and scale-up issues at the frontier of synthesis: Flow chemistry

“…The role of Pd in coupling reactions has been taken into account by critically assessing the role of the "heterogeneous" vs. "homogeneous" species playing a role in the reaction [79]. The life of heterogeneous Pd catalysts has been also considered by Reynolds et al [80] demonstrating negligible leaching. The opposite trend was proposed by Richardson et al [81], who focused on the role of leached Pd in the catalysis for coupling reactions.…”

Wool-anchored Pd(OAc)2 complex: a highly active and reusable catalyst for desulfurative coupling reactions

“…Different solvents were used in the reactions (entry 3,8,9), and among them, dioxane was the best one. Compared with the acetic acid and other aliphatic acids, 45 acrylic acids performed equally well with yields no less than the former examples (Scheme 3). In order to estimate the superiority 40 of wool-Pd(OAc) 2 complex compared to other palladium catalysts, palladium compounds as Pd(OAc) 2 (entry 13, 14), Pd(acac) 2 (entry 15), Pd 2 (dba) 3 (entry 16) and PdCl 2 (PPh 3 ) 2 (entry 17) was tested for their catalytic capacities in this reaction.…”

“…All NMR spectra are recorded on MERCURY (400 MHz for 1 H NMR, 100 MHz for 13 C NMR) spectrometers; chemical shifts are expressed in ppm (δ units) relative to TMS signal as internal reference in CDCl 3 . FTIR spectroscopy 45 patterns were obtained on an FT/IR-660 Plus system (Jasco, Tokyo, Japan). ICP-AES were measured on IRIS Advantage.…”

“…35 However, it is beyond doubt the high price restricts the catalytic utility for wider applications of this luxury. 19 In 2007, Liebeskind and co-workers reported the cross coupling of thiol 45 esters with boronic acids catalyzed by CuI-3-methylsalicylate (CuMeSal) instead of palladium, 12 and further techniques were continuously developed. Many transitionmetals have been tested for the desulfurative cross-coupling 40 reactions and performed diversely.…”

“…It is also a new and nevertheless robust 55 method of the transition-metal catalyzed synthesis in heterogeneous systems. [39][40][41][42][43][44][45][46] Studies 60 upon transition-metal complexes achieved tremendous progress, [47][48][49][50] and also inspired our explorations. and hybrid organic-inorganic (mainly grafted silica) supported transition-metal materials have been used in practice.…”