A facile iridium/graphene-catalyzed methodology providing an efficient synthetic route for C-N bond formation is reported. This catalyst can directly promote the formation of C-N bonds, without pre-activation steps, and without solvents, alkalis and other additives. This protocol provides a direct N -alkylation of amines using a variety of primary and secondary alcohols with good selectivity and excellent yields. Charmingly, the use of diols resulted in intermolecular cyclization of amines, and such products are privileged structures in biologically active compounds. Two examples illustrate the advantages of this catalyst in organic synthesis: the tandem catalysis to synthesize hydroxyine, and the intermolecular cyclyzation to synthesize cyclizine. Water is the only by-product, which makes this catalytic process sustainable and environmentally friendly.

Now day; the interest for the synthesis of heterocyclic compounds containing hydroquinoline fragments has increased tremendously due to their wide variety of pharmaceutical and industrial applications. This work details the synthesis of linear and fused heterocyclic systems containing hydroquinoline fragments and the pharmacological activity spectra of the synthesized compounds was predicted by in silico method using Prediction of Activity Spectra of Substances (PASS) program. 1,2,2,4-tetramethyl-1,2-dihydroquinoline-6-carbaldehyde 5a was reacted for three hours with a system of hydroxylammonium chloride/pyridinium chloride/toluene to produce 1,2,2,4-tetramethyl-1,2-dihydroquinoline-6-nitrile 7. N-benzyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-6-carbaldehyde 6b and iodine reacted at room temperature in aqueous ammonia water, followed by aq. treatment with Na2S2O3 and produced N-benzyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-6-nitrile 8. 30-60% 2-phenyl-1,3-oxazol-5(4H)-ones 9a,b; 10a,b were synthesized via the condensation reaction of N-alkylhydroquinoline-6-carbaldehydes 5a,b; 6a,b with hippuric acid in acetic acid. When activated 7-methylazolopyrimidines 11a,b were reacted with N-alkyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-6-carbaldehydes 6a,b, the reaction produced 60–70% yield of 7-[(E)-2,2,4-trimethylhydroquinolin-6-ylidenemethyl]azolo[1,5-a]pyrimidin-6-yl carboxylic acids 12a,b. The condensation reaction of 7-hydroxy-1,2,2,4-tetramethyl-1,2-dihydroquinoline 3h with dimethylacetylenedicarboxylate (DMAD) and ethylacetoacetate afforded methyl (Z)-2-(5,7,7,8-tetramethyl-2-oxo-7,8-dihydrofuro[3,2-g]quinolin-3(2H)-ylidene)acetate 16 and 4,6,8,8,9-pentamethyl-8,9-dihydro-2H-pyrano[3,2-g]quinolin-2-one 17, respectively. The condensation reaction of 6-formyl-7-hydroxy-1,2,2,4-tetramethyl-1,2-dihydroquinoline 5e with methylene active compounds ethylcyanoacetate/dimethyl-3-oxopentanedioate/ ethylacetoacetate/diethylmalonate/Meldrum’s acid afforded 3-substituted dihydroquinoline containg coumarins 19 & 21. A pentacyclic coumarin 22 was obtained via the random condensation reaction of malononitrile with 5e in the presence of catalytic amount of piperidine in ethanol. The potential biological activities of the synthesized compounds were evaluated using PASS computer program. According to the prognosis, (E)-4-(N-alkylhydroquinolin-6-yl)-3-buten-2-ones, 13a, b & 14 showed high probability of being active (Pa) as the Gluconate 2-dehydrogenase inhibitor, Anti-allergic, Anti-asthmatic, and Anti-arthritic with the Pa value of 0.849-0.870. It was also found out that hydroquinolinecarbonitrile compounds 7 & 8 have a propensity to act as a good progesterone antagonists, anti-allergic, anti-asthmatic, and anti-arthritic (Pa = 0.276-0.827). Among the coumarin moieties containing hydroquinolines, compounds 17, 19a, and 19c were predicted to be good progesterone antagonists with the Pa values of 0.710, 0.630 and 0.615; respectively.

The high interest in N-heterocyclic platinum carbene complexes in cancer research stems from their high cytotoxicity to human cancer cells, their stability, as well as their ease of functionalization. However, the development of these new molecules as anticancer agents still faces multiple challenges, in particular solubility in aqueous media. Here, we synthesized platinum-NHC bioconjugates that combine water-solubility and cytotoxicity by using polyethyleneimine as polymer carrier. We showed that the activity of these conjugates is modulated by the size of the polymer and the overall density of metal ions onto polymer chains. They displayed an effective activity after only 45 minutes of exposure in vitro correlated with a quick uptake by the cells as shown by the use of various fluorescent-tagged derivatives.

1-[5-(4-methylphenyl)-1,3,4-oxadiazol-2-yl]methanamine compound has been successfully synthesized by reacting p-Toluic hydrazide and glycine via polyphosphoric acid condensation route. The course of the reaction was found to be high yielding and the title compound was spectroscopically characterized by FT-IR, DSC, 13C/1H-NMR and Mass spectrometric techniques.

A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of -amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. Following optimization of the reaction conditions, NHC, and amino acid ligands, high enantioselectivity was achieved when employing the Ir(IMe)2(l-Pro)(H)(I) catalyst (IMe = 1,3-dimethylimidazol-2-ylidene), which asymmetrically reduces a range of acetophenone derivatives in up to 95% enantiomeric excess.

Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the two most common neurodegenerative diseases in elderly. The key histopathological features of these diseases are the presence of abnormal protein aggregates and the progressive and irreversible loss of neurons in specific brain regions. The exact mechanisms underlying the etiopathogenesis of AD or PD remain unknown, but there is extensive evidence indicating that excessive generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) along with a depleted antioxidant system, mitochondrial dysfunction, and intracellular Ca2+ dyshomeostasis play a vital role in the pathophysiology of these neurological disorders. Due to an improvement in life expectancy, the incidence of age-related neurodegenerative diseases has significantly increased. However, there is no effective protective treatment or therapy available but rather only very limited palliative treatment. Therefore, there is an urgent need for the development of preventive strategies and disease-modifying therapies to treat AD/PD. Because dysregulated Ca2+ metabolism drives oxidative damage and neuropathology in these diseases, the identification or development of compounds capable of restoring Ca2+ homeostasis and signaling may provide a neuroprotective avenue for the treatment of neurodegenerative diseases. In addition, a set of strategies to control mitochondrial Ca2+ homeostasis and signaling has been reported, including decreased Ca2+ uptake through voltage-operated Ca2+ channels (VOCCs). In this article, we review the modulatory effects of several heterocyclic compounds on Ca2+ homeostasis and trafficking, and their ability to regulate compromised mitochondrial function and associated free radical production during the onset and progression of AD or PD. This comprehensive review also describes the chemical synthesis of the heterocycles and summarizes the clinical trial outcomes.

The exploitation and use of alternative synthetic methods, in the face of classical procedures that do not conform to the ethics of Green Chemistry, represent an ever present problem in pharmaceutical industry. The procedures for the synthesis of benzimidazoles have become a focus in synthetic organic chemistry, as they are building blocks of strong interest for the development of compounds with pharmacological activity. Various benzimidazole derivatives exhibit important activities such as antimicrobial, antiviral, anti-inflammatory and analgesic and some of the already synthesized compounds have found very strong application in medicine praxis. Here we report a selective and sustainable method for the synthesis of 1,2-disubstituted or 2-substituted benzimidazoles, starting from o-phenylenediamine in the presence of different aldehydes. The use of deep eutectic solvent (DES) both as reaction medium and reagent without any external solvent provides advantages in terms of yields as well as in the work up procedure of the reaction.

In the past few decades, N-heterocyclic carbenes (NHCs) open the new field of organocatalysis in synthetic organic chemistry. This review highlights the dramatic progress in the NHC-catalyzed C−O bond formation based on the activation of aldehyde C(sp2)−H bonds. The oxidative and redox transformations for the synthesis of various molecules with structural diversity and complexity are summarized. Furthermore, new methods and strategies for NHC catalysis are emerging continuously; thus, cooperative catalysis with Brønsted acid, hydrogen-bonding catalyst, transition-metal catalyst, and photocatalyst is also described.

Several evidences suggest that the positive association between meat intake and colorectal adenoma (CRA) and cancer (CRC) risk is mediated by mutagenic compounds generated during cooking at high temperature. A number of epidemiological studies have estimated the effect of meat-related mutagens intake on CRC/CRA risk with contradictory and sometime inconsistent results. A literature search was carried out (PubMed, Web of Science and Scopus) to identify articles reporting the relationship between the intake of meat-related mutagens (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine: PhIP, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline: MeIQx, 2-amino-3,4,8-trimethylimidazo[4,5-f] quinoxaline: DiMeIQx, benzo(a) pyrene: (B(a)P) and “meat derived mutagenic activity”: MDM) and CRC/CRA risk. A random-effect model was used to calculate the risk association. Thirty-nine studies were included in the systematic review and meta-analysis. Polled CRA risk (15229 cases) was significantly increased by intake of PhIP (OR=1.20; 95%CI:1.13,1.28; p<0.001), MeIQx (OR=1.14; 95%CI:1.05,1.23; p=0.001), DiMeIQx (OR=1.13; 95%CI:1.05,1.21; p=0.001), B(a)P (OR=1.10; 95%CI:1.02,1.19; p=0.017) and MDM (OR=1.17; 95%CI:1.07,1.28; p=0.001). A linear and curvilinear trend was observed in dose-response meta-analisis between CRA risk in association with PhIP and MDM, MeIQx, respectively. CRC risk (21344 cases) was increased by uptake of MeIQx (OR=1.14; 95%CI:1.04,1.25; p=0.004), DiMeIQx (OR=1.12; 95%CI:1.02,1.22; p=0.014) and MDM (OR=1.12; 95%CI:1.06,1.19; p<0.001). No publication bias could be detected whereas heterogeneity was in some cases rather high. Mutagenic compounds formed during cooking of meat at high temperature may be responsible of its carcinogenicity.

Transition-metal-catalyzed amide bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further HR-MS analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.

The endo- and exo-N-heterocyclic carbene precursors based on camphor were prepared diastereoselectively in five synthetic steps starting from (1S)-(+)-ketopinic acid. The obtained N-heterocyclic carbene precursors were investigated in an asymmetric benzoin reaction. All new compounds were fully characterized and the absolute configurations were determined by X-ray diffraction and NOESY measurements.

A platinum (II) complex stabilized by a pyridine and a N-heterocyclic carbene ligand featuring an anthracenyl moiety was prepared. The compound was fully characterized and its molecular structure was determined by single-crystal X-ray diffraction. The compound demonstrated high in vitro antiproliferative activities against cancer cell lines with IC50 ranging from 10 to 80 nM. The presence of the anthracenyl moiety on the NHC Pt complex was used as a luminescent tag to probe the metal interaction with the nucleobases of the DNA through a pyridine-nucleobase ligand exchange. Such interaction of the platinum complex with DNA was corroborated by optical tweezers techniques and liquid phase AFM microscopy. The results revealed a two-state interaction between the platinum complex and the DNA strands. This two-state behaviour was quantified from the different experiments due to contour length variations. At 24h incubation, the stretching curves revealed multiple structural breakages, and AFM imaging revealed a highly compact and dense structure of platinum complexes bridging the DNA strands.