One-Step Synthesis of Biphenylacetic Acids via Pd/C-Catalyzed Arylation

Synthesis and characterization of a supported Pd complex on volcanic pumice laminates textured by cellulose for facilitating Suzuki-Miyaura cross-coupling reactions

Herein, a novel high-performance heterogeneous catalytic system made of volcanic pumice magnetic particles (VPMP), cellulose (CLS) natural polymeric texture, and palladium nanoparticles (Pd NPs) is presented. The introduced VPMP@CLS-Pd composite has been designed based on the principles of green chemistry, and suitably applied in the Suzuki-Miyaura cross-coupling reactions, as an efficient heterogeneous catalytic system. Concisely, the inherent magnetic property of VPMP (30 emu g-1) provides a great possibility for separation of the catalyst particles from the reaction mixture with great ease. In addition, high heterogeneity and high structural stability are obtained by this composition resulting in remarkable recyclability (ten times successive use). As the main catalytic sites, palladium nanoparticles (Pd NPs) are finely distributed onto the VPMP@CLS structure. To catalyze the Suzuki-Miyaura cross-coupling reactions producing biphenyl pharmaceutical derivatives, the present Pd NPs were reduced from chemical state Pd2+ to Pd0. In this regard, a plausible mechanism is submitted in the context as well. As the main result of the performed analytical methods (including FT-IR, EDX, VSM, TGA, FESEM, TEM, BTE, and XPS), it is shown that the spherical-shaped nanoscale Pd particles have been well distributed onto the surfaces of the porous laminate-shaped VPMP. However, the novel designed VPMP@CLS-Pd catalyst is used for facilitating the synthetic reactions of biphenyls, and high reaction yields (∼98%) are obtained in a short reaction time (10 min) by using a small amount of catalytic system (0.01 g), under mild conditions (room temperature).

Ultrasound Assisted Synthesis of 3-(het)aryl Isocoumarin Derivatives and their in vitro Pharmacological Evaluation

BACKGROUND

In view of numerous biological activities of 3-substituted isocoumarins a number of analogues based on this scaffold were synthesized for their in vitro pharmacological evaluation.

METHODS

The syntheses of 3-substituted isocoumarins were carried out via a Pd/C-catalyzed Suzuki- Miyaura coupling of 3-chloroisochromen-1-one with a range of boronic acid derivatives. This C-C bond forming reaction was facilitated by ultrasound irradiation to afford the desired products in good yields. A number of 3-(het)aryl isocoumarin derivatives were prepared by using this methodology and subsequently tested for their TNF-α inhibitory properties in vitro followed by cytotoxicities via the MTT assay.

RESULTS

Several compounds showed inhibition of TNF-α with one compound showing an IC50 value of 9.01±1.25 µM. Three compounds also showed promising cytotoxic properties against two cancer cell lines with IC50 ~ 0.9-2.7 µM.

CONCLUSION

The isocoumarin framework could be an effective template for the design and discovery of new inhibitor of TNF-α for the potential treatment of related diseases.

Continuous-Flow Suzuki-Miyaura and Mizoroki-Heck Reactions under Microwave Heating Conditions

Microwave-assisted continuous-flow reactions have attracted significant interest from synthetic organic chemists, especially process chemists from practical points of view, due to a less complicated shift to large-scale synthesis based on simple and continuous access to products with low energy requirements. In this personal account, we focused on the Suzuki-Miyaura and Mizoroki-Heck reactions, both of which are significantly important cross-coupling reactions for the synthesis of various functional materials. Microwave power is effective for heating. Typical homogeneous palladium catalysts, such as PdCl₂ (PPh₃ )₂ , Pd(PPh₃ )₄ , and Pd(OAc)₂ , as well as heterogeneous palladium catalysts, such as Pd-film, Pd/Al₂ O₃ , Pd/SiO₂ , and Pd supported on polymers, can be used for these reactions.

One-pot two-step synthesis of 3-iodo-4-aryloxy coumarins and their Pd/C-catalyzed annulation to coumestans

An efficient protocol for the synthesis of various coumestans from the intramolecular annulation of 3-iodo-4-aryloxy coumarins through C–H activation has been developed.

Metal-supported carbon-based materials: opportunities and challenges in the synthesis of valuable products

We summarize relevant applications and limitations of metal-supported carbons and nanocarbons in the synthesis of valuable products and the recent advances in this field.

A study of the Willgerodt–Kindler reaction to obtain thioamides and α-ketothioamides under solvent-less conditions

In this paper, the results obtained in the synthesis of thioamides and α-ketothioamides by a modification of the Willgerodt–Kindler reaction, under solvent-free and noncatalyst conditions using IR energy as a source of activation, are presented. The use of IR energy in these reactions has been shown to lead to a mixture of thioamide and α-ketothioamide as the main products in most cases, with the latter predominating. The yields of α-ketothioamides from most of these reactions are better than those reported previously. To the best of our knowledge, this is the first time that IR energy has been applied to promote the Willgerodt–Kindler reaction.

CD22-antagonists with nanomolar potency: the synergistic effect of hydrophobic groups at C-2 and C-9 of sialic acid scaffold

In earlier studies, we identified the C-9 amido derivative 1 (9-(4'-hydroxy-4-biphenyl)acetamido-9-deoxy-Neu5Gcα2-6GalOMP) and the C-9 amino derivative 2 (9-(4'-hydroxy-4-biphenyl)methylamino-9-deoxy-Neu5Gcα2-6GalOMP) have the most promising affinity for mouse CD22 and human CD22, respectively. Replacing the subterminal galactose residue (2-6Gal-OMP) of 1 with benzyl (5) or biphenylmethyl (6) as aglycone led to even higher potency for mCD22. In this study, both compounds showed improved potency and selectivity for CD22 (IC(50) 70 nM) and 712-fold more selective for CD22 than for MAG. The corresponding derivatives of 2, compounds 8 and 9, showed comparable activity to 2 but lower potency and selectivity than 5 and 6. Although compounds 5-9 are simple and small molecular weight antagonists, they showed much high potency and selectivity than the corresponding compounds having α 2-6Gal linkage. Both biological and computational docking simulation studies suggest that the 2-6Gal-OMP residues of 1 and 2 are not critical for binding process and could be replaced with hydrophobic non-carbohydrate moieties. The data presented herein has significant implications for the design and discovery of next-generation CD22-antagonists.

Heterogeneous Pd/C-Catalyzed Ligand-Free, Room-Temperature Suzuki–Miyaura Coupling Reactions in Aqueous Media

A mild and efficient ligand-free Suzuki-Miyaura coupling reaction catalyzed by heterogeneous Pd/C was developed. Aryl bromides and triflates undergo the cross-coupling with aryl boronic acids in excellent yields without the presence of any additives in aqueous media at room temperature. Aryl vinyl boronic acids are also applicable to this coupling reaction and provide the trans-stilbene derivatives in high yields. The application of wet-type Pd/C to the coupling reaction was achieved without any loss of activity under aerobic conditions, and the reuse of Pd/C is feasible for a fifth run without significant loss of activity. Inductively coupled plasma (ICP) mass-spectrometric analysis of the filtrate from the reaction mixture of 4-bromonitrobenzene with phenylboronic acid demonstrated that the palladium metal hardly leached into the solution within the limits of the detector (<1 ppm), thus suggesting that the present Suzuki-Miyaura reaction proceeded by heterogeneous catalysis.

The identification, synthesis, protein crystal structure and in vitro biochemical evaluation of a new 3,4-diarylpyrazole class of Hsp90 inhibitors

High-throughput screening identified the 3,4-diarylpyrazole CCT018159 as a novel and potent (7.1 microM) inhibitor of Hsp90 ATPase activity. Here, we describe the synthesis of CCT018159 and a number of close analogues together with data on their biochemical properties. Some initial structure-activity relationships are discussed, as well as the crystal structure of CCT018159 bound to Hsp90.

Fast, easy, clean chemistry by using water as a solvent and microwave heating: the Suzuki coupling as an illustration

Water is an excellent solvent for organic chemistry and microwave heating offers a very efficient way of heating reaction mixtures. In this article, by focusing on the Suzuki reaction, it is shown how these two methods, used alone or together, can impact modern synthetic chemistry, making reactions faster, easier and cleaner.

Suzuki Coupling of Aryl Chlorides with Phenylboronic Acid in Water, Using Microwave Heating with Simultaneous Cooling

[reaction: see text]. We present here a methodology for the Suzuki coupling of aryl chlorides with phenylboronic acid using Pd/C as a catalyst, water as a solvent, and microwave heating. We show that simultaneous cooling in conjunction with microwave heating prolongs the lifetime of the aryl chloride substrates during the course of the reaction and, as a result, yields of the desired biaryl as well as overall recovery of material can be increased.

Palladium Charcoal-Catalyzed Suzuki−Miyaura Coupling To Obtain Arylpyridines and Arylquinolines

A phosphine ligand, such as PPh3 or 2-(dicyclohexylphosphino)biphenyl, is essential for the Pd/C-catalyzed Suzuki-Miyaura coupling of halopyridines and haloquinolines, although it has been reported that the reaction of phenyl chlorides can be catalyzed by nonprereduced Pd/C without any additives. In the reactions of bromopyridines, bromoquinolines, 2-chloropyridines, and 2-chloroquinolines, PPh3 was effective enough to provide coupling products in good yields. However, in the reactions of 3-chloropyridine, 4-chloropyridine, and 6-chloroquinoline, sterically hindered 2-(dicyclohexylphosphino)biphenyl was indispensable as a ligand.