Carboxymethylcellulose‐supported palladium nanoparticles generated in situ from palladium(II) carboxymethylcellulose as an efficient and reusable catalyst for ligand‐ and base‐free Heck–Matsuda and Suzuki–Miyaura couplings

Abstract

A novel palladium(II) carboxymethylcellulose (CMC-Pd II ) was prepared by direct metathesis from sodium carboxymethylcellulose and PdCl 2 in aqueous solution. Its catalytic activities were explored for Heck-Matsuda reactions of aryldiazonium tetrafluoroborate with olefins, and Suzuki-Miyaura couplings of aryldiazonium tetrafluoroborate with arylboronic acid. Both reactions proceeded at room temperature in water or aqueous ethanol media without the presence of any ligand or base, to provide the corresponding cross-coupling products in good to excellent yields under atmospheric conditions. The CMC-Pd II and carboxymethylcellulose-supported palladium nanoparticles (CMC-Pd 0 ) formed in situ in the reactions were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, inductively coupled plasma atomic emission spectrometry, and scanning and transmission electron microscopies. The homogeneous nature of the CMC-Pd 0 catalyst was confirmed via Hg(0) and CS 2 poisoning tests. Moreover, the CMC-Pd 0 catalyst could be conveniently recovered by simple filtration and reused for at least ten cycles in Suzuki-Miyaura reactions without apparently losing its catalytic activity. The catalytic system not only overcomes the basic drawbacks of homogeneous catalyst recovery and reuse but also avoids the need to fabricate palladium nanoparticles in advance.

ChemInform Abstract: Heterogeneous Palladium Catalysts for Suzuki—Miyaura Coupling Reactions Involving Aryl Diazonium Salts

“…Recently,L ia nd co-workers described the preparation of carboxymethylcellulose-supported palladium nanoparticles (Pd/ CMC) as av ery efficient and reusable catalystf or cross-coupling reactions, [22] including the coupling of aryl diazonium salts. [23] Thea uthors prepared the pre-catalyst by mixing an aqueous solution of sodium carboxymethylcellulose (CMC-Na) with an aqueous solution of PdCl 2 ,p roviding Pd II /CMC as ab rown powder ( Figure 5). The Pd loading was determined to be 3.83 mmolg À1 of materialbyI CP-AES.…”

Cobalt Schiff Base Immobilized on a Graphene Nanosheet with N, O Linkage for Cross-Coupling Reaction

“…Suzuki–Miyaura cross-coupling reaction is an extensively known method for carbon–carbon bond formation in organic synthesis which includes from the manufacture, i.e., small complex intermediates to the industrially viable active pharmaceutical ingredients (APIs) . Of all of the various transition metals, palladium is predominantly used for this. − However, with palladium being a precious metal, high cost volatility prohibits its usage in huge quantities. Due to the search for alternative catalytic methodology, which employs a suitable transition metal first row element such as cobalt and iron transition metals which is an important approach due to its sustainability in its ecofriendly nature. − …”

Cerium(IV) carboxymethylcellulose (CMC −Ce I V ) as an efficient and reusable catalyst for the one-pot pseudo-four component synthesis of 2,4,6-triphenylpyridines

“…More recently, we have reported the employment of CMC as a support for stabilization of palladium nanoparticles and its applications in Suzuki-Miyaura and Heck-Mizoroki coupling reactions. 25,26 On the basis of ion-exchange property of CMC−Na, for the first time, we herein report the preparation of the CMC−Ce IV via metathesis of Ce 4+ with CMC−Na in aqueous solution (Scheme 1), and further report its application as an excellent recyclable novel catalyst in pseudo-four component reactions for the synthesis of Kröhnke pyridines under solvent-free condition in air (Scheme 2).…”