Schiff base modified starch: A promising biosupport for palladium in Suzuki cross-coupling reactions.

Starch can be used in diverse fields because it is a readily available, non-toxic polysaccharide with adaptable functionality and biodegradability. In this study, taking the aforementioned characteristics into consideration, we designed a modified starch (Starch-SB), which serves as supporting material for palladium stabilization. This new air and moisture-stable robust palladium composite [Starch-SB-Pd(II)] was characterized by FT-IR, XRD, TGA, XPS, SEM, EDX, TEM, CP/MAS 13C NMR, and ICP-MS analytical techniques. The catalytic studies exhibit high activity (up to 99 %) and stability in Suzuki cross-coupling reactions for this starch supported catalytic system under mild conditions (lower reaction temperature and green solvents) because of the cooperative interactions of multifunctional capturing sites on starch (Schiff base, hydroxy and amine groups) with palladium species. The experiments on reusability demonstrate that Starch-SB-Pd(II), which was prepared from functionalized starch, could be readily recycled several cycles through centrifugation. Moreover, we proposed a possibly multifunctional complex structure. This work presents an appealing and intriguing pathway for the utilization of polysaccharide as crucial support in green chemical transformations.

New fused pyrroles with rA1/A2A antagonistic activity as potential therapeutics for neurodegenerative disorders.

In a pilot study, eleven pyrrolopyridine and pyrrolopyrimidine derivatives (specifically, 7-azaindole and 7-deazapurine derivatives) were synthesised by Suzuki cross-coupling reactions and evaluated via radioligand binding assays as potential adenosine receptor (AR) antagonists in order to further investigate the structure-activity relationships of these compounds. 6-Chloro-4-phenyl-1H-pyrrolo[2,3-b]pyridine, with a 7-azaindole scaffold, was identified as a selective A1 AR antagonist with a rA1Ki value of 0.16 µM, and interestingly, the addition of a N-atom to the aforementioned fused heterocyclic ring system, creating corresponding 7-deazapurines, led to a dual A1/A2A AR ligand (2-chloro-4-phenyl-7H-pyrrolo[2,3-d]pyrimidine: rA1Ki: 0.19 ± 0.02 µM; rA2AKi: 0.43 ± 0.01 µM). Introducing an additional N-atom into the heterocyclic ring system was tolerable for rA1 AR affinity and also led to rA2A AR affinity. This pilot study concluded that new 7-azaindole and 7-deazapurine derivatives represent interesting scaffolds for design of A1 and/or A2A AR antagonists.

Synthesis, Density Functional Theory (DFT), Urease Inhibition and Antimicrobial Activities of 5-Aryl Thiophenes Bearing Sulphonylacetamide Moieties.

A variety of novel 5-aryl thiophenes 4a-g containing sulphonylacetamide (sulfacetamide) groups were synthesized in appreciable yields via Pd[0] Suzuki cross coupling reactions. The structures of these newly synthesized compounds were determined using spectral data and elemental analysis. Density functional theory (DFT) studies were performed using the B3LYP/6-31G (d, p) basis set to gain insight into their structural properties. Frontier molecular orbital (FMOs) analysis of all compounds 4a-g was computed at the same level of theory to get an idea about their kinetic stability. The molecular electrostatic potential (MEP) mapping over the entire stabilized geometries of the molecules indicated the reactive sites. First hyperpolarizability analysis (nonlinear optical response) were simulated at the B3LYP/6-31G (d, p) level of theory as well. The compounds were further evaluated for their promising antibacterial and anti-urease activities. In this case, the antibacterial activities were estimated by the agar well diffusion method, whereas the anti-urease activities of these compounds were determined using the indophenol method by quantifying the evolved ammonia produced. The results revealed that all the sulfacetamide derivatives displayed antibacterial activity against Bacillus subtiles, Escherichia coli, Staphylococcus aureus, Shigella dysenteriae, Salmonella typhae, Pseudomonas aeruginosa at various concentrations. Furthermore, the compound 4g N-((5-(4-chlorophenyl)thiophen-2-yl)sulfonyl) acetamide showed excellent urease inhibition with percentage inhibition activity ~46.23 ± 0.11 at 15 µg/mL with IC50 17.1 µg/mL. Moreover, some other compounds 4a-f also exhibited very good inhibition against urease enzyme.

A highly active recyclable gold-graphene nanocomposite material for oxidative esterification and Suzuki cross-coupling reactions in green pathway.

A graphene based composite with gold nanoparticles has been synthesized via a simple chemical route and the structure and compositions of nanocomposite has been characterized. The catalyst was found to be remarkably stable and active for the oxidative esterification of alcohols under present reaction conditions using molecular oxygen as green oxidant and Suzuki cross-coupling reactions between aryl halides and phenylboronic acids using environmentally friendly water as solvent. The versatility of both the protocols was demonstrated by taking a number of substrates. This protocol offers several advantages like high yields, clean reactions, recyclability of the catalyst, reaction in water and use of green oxidant. This study suggests graphene, as an economical substitute for carbon nanotubes, could act as a prominent support in heterogeneous catalysis.

Regioselective synthesis of 2-(bromomethyl)-5-aryl-thiophene derivatives via palladium (0) catalyzed suzuki cross-coupling reactions: as antithrombotic and haemolytically active molecules.

BACKGROUND: It is seen that the regioselective functionalizations of halogenated heterocycles play an important role in the synthesis of several types of organic compounds. In this domain, the Suzuki-Miyaura reaction has emerged as a convenient way to build carbon-carbon bonds in synthesizing organic compounds. Some of the most important applications of these reactions can be seen in the synthesis of natural products, and in designing targeted pharmaceutical compounds. Herein, we present the regioselective synthesis of the novel series of 2-(bromomethyl)-5-aryl-thiophenes 3a-i, via Suzuki cross-coupling reactions of various aryl boronic acids with 2-bromo-5-(bromomethyl)thiophene (2). RESULTS: The synthesized compounds were screened for their haemolytic and antithrombolytic activities. The novel compounds 3f, 3i showed highest 69.7, 33.6% haemolysis of blood cells, respectively. The antithrombolytic activity of the compounds was found to be within low to moderate against human blood clot. The compound 3i showed potent clot lysis (31.5%). CONCLUSIONS: Considering these results, it is concluded that the synthesized compounds can be used as a promising source of therapeutic agents.