A simple and efficient protocol for a palladium-catalyzed ligand-free Suzuki reaction at room temperature in aqueous DMF

Abstract

A convenient, effective and mild protocol has been developed for the palladium-catalyzed ligand-free Suzuki reaction of aryl bromides with arylboronic acids in aqueous N,N-dimethylformamide (DMF) in the presence of K 2 CO 3 and a catalytic amount of PdCl 2 in air at room temperature. It is noteworthy that the volume ratio of water-DMF and base play important roles in the reaction, and various functional groups are tolerated under the optimized conditions. Furthermore, this protocol could be extended to the cross-couplings of nitrogen-based heteroaryl halides with arylboronic acids in moderate to excellent yields.

Synthesis of 4-Methoxybiphenyl Using Pd-Containing Catalysts Based on Polymeric Matrix of Functionalized Hypercrosslinked Polystyrene

“…Water is an environmentally friendly solvent; besides, polar solvents are preferable due to the possibility of enhancing of the catalyst stability [13]. However the rate of cross-coupling in pure water is extremely low in comparison with organic solvent-water mixtures [26,27]. This fact can be explained by insufficient solubility of substrates in water and also by the difficulty of Pd(II) reduction that is an essential step of the Suzuki reaction mechanism.…”

“…In order to achieve high activity in the case of pure solvents (water or organic solvents), the addition of phase transfer agents is necessary [16,20]. Promising results were obtained in the case of organic solvent-water mixtures, but it is noteworthy that the choice of an optimal water content is important [26].…”

“…In general, a large variety of solvents is used, such as THF, dioxane, dimethyl ether, acetonitrile, N,N-dimethylformamide, low-molecular weight alcohols (methanol, EtOH, PrOH, butanol, etc. ), water, and also mixtures of solvents [10,11,13,25,26]. Water is an environmentally friendly solvent; besides, polar solvents are preferable due to the possibility of enhancing of the catalyst stability [13].…”

Palladium-Catalyzed Suzuki Reactions in Water with No Added Ligand: Effects of Reaction Scale, Temperature, pH of Aqueous Phase, and Substrate Structure

“…However, the limited solubility of the halogenated substrates and ligands in water often leads to slow rate and low yields. To overcome this limitation, alternative methodologies using water-soluble ligands, [52][53][54][55][56] organic co-solvents, [25][26][27][28][29][30][31][32] phase-transfer catalysts 33,[48][49][50][51] and inorganic salt promoters, 34,35 and heating with microwave or ultrasound were reported. [36][37][38][39][40] In 1989, Bumagin et al 57 were the first to report a Pd(OAc) 2 catalyzed Suzuki reaction of phenylboronic acid with aryl iodides containing a -OH or -COOH substituents; Na 2 CO 3 was employed as the base in neat water under an argon atmosphere.…”

Facile synthesis of mono-, bis- and tris-aryl-substituted aniline derivatives in aqueous DMF

“…This was consistent with our reported results. [37][38][39] Hence, Pd(OAc) 2 is the best choice. Table 2, it is clear that the higher the temperature was, the better the result was obtained.…”