Solvent-Free Synthesis of Core-Functionalised Naphthalene Diimides by Using a Vibratory Ball Mill: Suzuki, Sonogashira and Buchwald-Hartwig Reactions.

Solvent-free synthesis by using a vibratory ball mill (VBM) offers the chance to access new chemical reactivity, whilst reducing solvent waste and minimising reaction times. Herein, we report the core functionalisation of N,N'-bis(2-ethylhexyl)-2,6-dibromo-1,4,5,8-naphthalenetetracarboxylic acid (Br2 -NDI) by using Suzuki, Sonogashira and Buchwald-Hartwig coupling reactions. The products of these reactions are important building blocks in many areas of organic electronics including organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVCs). The reactions proceed in as little as 1 h, use commercially available palladium sources (frequently Pd(OAc)2 ) and are tolerant to air and atmospheric moisture. Furthermore, the real-world potential of this green VBM protocol is demonstrated by the double Suzuki coupling of a monobromo(NDI) residue to a bis(thiophene) pinacol ester. The resulting dimeric NDI species has been demonstrated to behave as an electron acceptor in functioning OPVCs.

A Convenient, Rapid, Conventional Heating Route to MIDA Boronates.

A cheap, conventional, sealed heating reactor proved to be a useful alternative to a microwave reactor in the synthesis of a >20-member MIDA boronate library (MIDA = N-methyliminodiacetic acid). Reaction times were 10 min and work-ups were minimal, saving on energy and solvent usage.

Genotoxicity and Epigenotoxicity of Carbazole-Derived Molecules on MCF-7 Breast Cancer Cells.

The carbazole compounds PK9320 (1-(9-ethyl-7-(furan-2-yl)-9H-carbazol-3-yl)-N-methylmethanamine) and PK9323 (1-(9-ethyl-7-(thiazol-4-yl)-9H-carbazol-3-yl)-N-methylmethanamine), second-generation analogues of PK083 (1-(9-ethyl-9H-carbazol-3-yl)-N-methylmethanamine), restore p53 signaling in Y220C p53-mutated cancer cells by binding to a mutation-induced surface crevice and acting as molecular chaperones. In the present paper, these three molecules have been tested for mutant p53-independent genotoxic and epigenomic effects on wild-type p53 MCF-7 breast adenocarcinoma cells, employing a combination of Western blot for phospho-γH2AX histone, Comet assay and methylation-sensitive arbitrarily primed PCR to analyze their intrinsic DNA damage-inducing and DNA methylation-changing abilities. We demonstrate that small modifications in the substitution patterns of carbazoles can have profound effects on their intrinsic genotoxic and epigenetic properties, with PK9320 and PK9323 being eligible candidates as "anticancer compounds" and "anticancer epi-compounds" and PK083 a "damage-corrective" compound on human breast adenocarcinoma cells. Such different properties may be exploited for their use as anticancer agents and chemical probes.

Diterpenoids of terrestrial origin.

Covering January to December 2017; previous review Nat. Prod. Rep., 2017, 34, 1233-1243. This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes labdanes, clerodanes, abietanes, pimaranes, kauranes, cembranes and their cyclization products. There are 228 references.

The effect of RO3201195 and a pyrazolyl ketone P38 MAPK inhibitor library on the proliferation of Werner syndrome cells.

Microwave-assisted synthesis of the pyrazolyl ketone p38 MAPK inhibitor RO3201195 in 7 steps and 15% overall yield, and the comparison of its effect upon the proliferation of Werner Syndrome cells with a library of pyrazolyl ketones, strengthens the evidence that p38 MAPK inhibition plays a critical role in modulating premature cellular senescence in this progeroid syndrome and the reversal of accelerated ageing observed in vitro on treatment with SB203580.

Microwave-assisted synthesis of 3-aminobenzo[b]thiophene scaffolds for the preparation of kinase inhibitors.

Microwave irradiation of 2-halobenzonitriles and methyl thioglycolate in the presence of triethylamine in DMSO at 130 °C provides rapid access to 3-aminobenzo[b]thiophenes in 58-96% yield. This transformation has been applied in the synthesis of the thieno[2,3-b]pyridine core motif of LIMK1 inhibitors, the benzo[4,5]thieno[3,2-e][1,4]diazepin-5(2H)-one scaffold of MK2 inhibitors and a benzo[4,5]thieno[3,2-d]pyrimidin-4-one inhibitor of the PIM kinases.

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor.

The Bohlmann-Rahtz pyridine synthesis and the Hantzsch dihydropyridine synthesis can be carried out in a microwave flow reactor or using a conductive heating flow platform for the continuous processing of material. In the Bohlmann-Rahtz reaction, the use of a Brønsted acid catalyst allows Michael addition and cyclodehydration to be carried out in a single step without isolation of intermediates to give the corresponding trisubstituted pyridine as a single regioisomer in good yield. Furthermore, 3-substituted propargyl aldehydes undergo Hantzsch dihydropyridine synthesis in preference to Bohlmann-Rahtz reaction in a very high yielding process that is readily transferred to continuous flow processing.

Synthesis and Evaluation of a Silver Nanoparticle/Polyurethane Composite That Exhibits Antiviral Activity against SARS-CoV-2.

In this proof-of-concept study, we aim to produce a polyurethane (PU)-based composite that can reduce the amount of viable SARS-CoV-2 virus in contact with the surface of the polymeric film without further interventions such as manual cleaning. Current protocols for maintaining the hygiene of commonly used touchpoints (door handles, light switches, shop counters) typically rely on repeated washing with antimicrobial products. Since the start of the SARS-CoV-2 pandemic, frequent and costly surface sanitization by workers has become standard procedure in many public areas. Therefore, materials that can be retrofitted to touchpoints, yet inhibit pathogen growth for extended time periods are an important target. Herein, we design and synthesise the PU using a one-pot synthetic procedure on a multigram scale from commercial starting materials. The PU forms a robust composite thin film when loaded with 10 wt% silver nanoparticles (AgNPs). The addition of AgNPs increases the ultimate tensile strength, modules of toughness and modulus of elasticity at the cost of a reduced elongation at break when compared to the pristine PU. Comparative biological testing was carried out by the addition of pseudotyped virus (PV) bearing the SARS-CoV-2 beta (B.1.351) VOC spike protein onto the film surfaces of either the pristine PU or the PU nanocomposite. After 24 h without further human intervention the nanocomposite reduced the amount of viable virus by 67% (p = 0.0012) compared to the pristine PU treated under the same conditions. The significance of this reduction in viable virus load caused by our nanocomposite is that PUs form the basis of many commercial paints and coatings. Therefore, we envisage that this work will provide the basis for further progress towards producing a retrofittable surface that can be applied to a wide variety of common touchpoints.

Expanding the Repertoire of Low-Molecular-Weight Pentafluorosulfanyl-Substituted Scaffolds.

The pentafluorosulfanyl (-SF5 ) functional group is of increasing interest as a bioisostere in medicinal chemistry. A library of SF5 -containing compounds, including amide, isoxazole, and oxindole derivatives, was synthesised using a range of solution-based and solventless methods, including microwave and ball-mill techniques. The library was tested against targets including human dihydroorotate dehydrogenase (HDHODH). A subsequent focused approach led to synthesis of analogues of the clinically used disease modifying anti-rheumatic drugs (DMARDs), Teriflunomide and Leflunomide, considered for potential COVID-19 use, where SF5 bioisostere deployment led to improved inhibition of HDHODH compared with the parent drugs. The results demonstrate the utility of the SF5 group in medicinal chemistry.

Continuous flow processing from microreactors to mesoscale: the Bohlmann-Rahtz cyclodehydration reaction.

The cyclodehydration of a number of Bohlmann-Rahtz aminodienones exemplifies the use of continuous flow processing to transfer operations from commercial microreactors and microwave batch reactors to mesoscale production using different technology platforms, including a microwave flow reactor.

Bohlmann-Rahtz cyclodehydration of aminodienones to pyridines using N-iodosuccinimide.

Cyclodehydration of Bohlmann-Rahtz aminodienone intermediates using N-iodosuccinimide as a Lewis acid proceeds at low temperature under very mild conditions to give the corresponding 2,3,6-trisubstituted pyridines in high yield and with total regiocontrol.

Selective targeting of the αC and DFG-out pocket in p38 MAPK.

The p38 MAPK cascade is a key signaling pathway linked to a multitude of physiological functions and of central importance in inflammatory and autoimmune diseases. Although studied extensively, little is known about how conformation-specific inhibitors alter signaling outcomes. Here, we have explored the highly dynamic back pocket of p38 MAPK with allosteric urea fragments. However, screening against known off-targets showed that these fragments maintained the selectivity issues of their parent compound BIRB-796, while combination with the hinge-binding motif of VPC-00628 greatly enhanced inhibitor selectivity. Further efforts focused therefore on the exploration of the αC-out pocket of p38 MAPK, yielding compound 137 as a highly selective type-II inhibitor. Even though 137 is structurally related to a recent p38 type-II chemical probe, SR-318, the data presented here provide valuable insights into back-pocket interactions that are not addressed in SR-318 and it provides an alternative chemical tool with good cellular activity targeting also the p38 back pocket.

Microwave-assisted Ullmann C-S bond formation: synthesis of the P38alpha MAPK clinical candidate VX-745.

Microwave irradiation promotes the rapid and efficient reaction of a thiophenol and aryl or heteroaryl halide using a copper or palladium catalyst and a range of ligands, depending upon substrate. Of particular utility is the use of copper(I) iodide (5 mol %) and trans-cyclohexane-1,2-diol as ligand under basic conditions and microwave irradiation to give the corresponding sulfide in high yield. This method for C-S bond formation is applied in the four-step synthesis of the clinical candidate VX-745 in 38% overall yield. The inhibitory activity of VX-745 against p38alpha MAPK is confirmed in Werner syndrome dermal fibroblasts at 1.0 microM concentration by immunoblot assay.

Microwave-assisted synthesis of 5-aminopyrazol-4-yl ketones and the p38(MAPK) inhibitor RO3201195 for study in Werner syndrome cells.

5-Aminopyrazol-4-yl ketones are prepared rapidly and efficiently using microwave dielectric heating from beta-ketonitriles by treatment with N,N'-diphenylformamidine followed by heterocyclocondensation by irradiation with a hydrazine. The inhibitory activity of RO3201195 prepared by this methodology was confirmed in hTERT-immortalized HCA2 and WS dermal fibroblasts at 200nM concentration, both by ELISA and immunoblot assay, and displays excellent kinase selectivity for p38alpha MAPK over the related stress-activated kinase JNK.

Direct alpha-oxytosylation of carbonyl compounds: one-pot synthesis of heterocycles.

N-Methyl-O-tosylhydroxylamine is an effective reagent for the direct alpha-oxytosylation of carbonyl compounds. The reactions proceed smoothly at room temperature in the presence of both moisture and air and functional group tolerance in the substrate is good. With nonsymmetrical substrates regioselectivity for primary over secondary centers is observed and complete regiospecificity for primary over tertiary centers is obtained. Addition of a bis-heteronucleophile directly to the crude reaction mixture in a one-pot process leads to the corresponding heterocyclic product.

The role of cellular senescence in Werner syndrome: toward therapeutic intervention in human premature aging.

Werner syndrome (WS) is a premature aging disorder used as a model of normal human aging. WS individuals have several characteristics of normal aging, such as cataracts, hair graying, and skin aging, but manifest these at an early age. Additionally, WS individuals have high levels of inflammatory diseases, such as atherosclerosis and type 2 diabetes. The in vivo aging in WS is associated with accelerated aging of fibroblasts in culture. The cause of the accelerated senescence is not understood, but may be due to the genomic instability that is a hallmark of WS. Genome instability results in activation of stress kinases, such as p38, and the p38-specific inhibitor SB203580, prevents the accelerated senescence seen in WS fibroblasts. However, oxidative damage plays a role, as low oxygen conditions and antioxidant treatment revert some of the accelerated senescence phenotype. The effects of oxidative stress appear to be suppressible by SB203580; however, it does not appear to be transduced by p38. As SB203580 is known to inhibit other kinases in addition to p38, this suggests that more than one kinase pathway is involved. The recent development of p38 inhibitors with different binding properties, specificities, and oral bioavailability, and of new potent and selective inhibitors of JNK and MK2, will make it possible to dissect the roles of various kinase pathways in the accelerated senescence of WS cells. If this accelerated senescence is reflective of WS aging in vivo, these kinase inhibitors may well form the basis of antiaging therapies for individuals with WS.

Synthesis and in vivo activity of MK2 and MK2 substrate-selective p38alpha(MAPK) inhibitors in Werner syndrome cells.

A benzopyranopyridine inhibitor of mitogen-activated protein kinase-activated protein kinase 2 (MK2) is prepared rapidly and efficiently in one step using microwave dielectric heating, whereas a substrate-selective p38 MAPK inhibitor was prepared using conventional heating techniques. The former had MK2 inhibitory activity above 2.5 microM concentration, whereas the latter showed no MK2 inhibition at 10 microM. However, rather than rescuing the reduced cellular growth rate and aged morphology of hTERT-immortalised WS dermal fibroblasts, both induce a state resembling stress-induced cellular senescence, suggesting that these inhibitors may have limited therapeutic use.

Evaluating the Role of p38 MAPK in the Accelerated Cell Senescence of Werner Syndrome Fibroblasts.

Progeroid syndromes show features of accelerated ageing and are used as models for human ageing, of which Werner syndrome (WS) is one of the most widely studied. WS fibroblasts show accelerated senescence that may result from p38 MAP kinase activation since it is prevented by the p38 inhibitor SB203580. Thus, small molecule inhibition of p38-signalling may be a therapeutic strategy for WS. To develop this approach issues such as the in vivo toxicity and kinase selectivity of existing p38 inhibitors need to be addressed, so as to strengthen the evidence that p38 itself plays a critical role in mediating the effect of SB203580, and to find an inhibitor suitable for in vivo use. In this work we used a panel of different p38 inhibitors selected for: (1) having been used successfully in vivo in either animal models or human clinical trials; (2) different modes of binding to p38; and (3) different off-target kinase specificity profiles, in order to critically address the role of p38 in the premature senescence seen in WS cells. Our findings confirmed the involvement of p38 in accelerated cell senescence and identified p38 inhibitors suitable for in vivo use in WS, with BIRB 796 the most effective.

Effect of flecainide derivatives on sarcoplasmic reticulum calcium release suggests a lack of direct action on the cardiac ryanodine receptor.

BACKGROUND AND PURPOSE: Flecainide is a use-dependent blocker of cardiac Na(+) channels. Mechanistic analysis of this block showed that the cationic form of flecainide enters the cytosolic vestibule of the open Na(+) channel. Flecainide is also effective in the treatment of catecholaminergic polymorphic ventricular tachycardia but, in this condition, its mechanism of action is contentious. We investigated how flecainide derivatives influence Ca(2) (+) -release from the sarcoplasmic reticulum through the ryanodine receptor channel (RyR2) and whether this correlates with their effectiveness as blockers of Na(+) and/or RyR2 channels. EXPERIMENTAL APPROACH: We compared the ability of fully charged (QX-FL) and neutral (NU-FL) derivatives of flecainide to block individual recombinant human RyR2 channels incorporated into planar phospholipid bilayers, and their effects on the properties of Ca(2) (+) sparks in intact adult rat cardiac myocytes. KEY RESULTS: Both QX-FL and NU-FL were partial blockers of the non-physiological cytosolic to luminal flux of cations through RyR2 channels but were significantly less effective than flecainide. None of the compounds influenced the physiologically relevant luminal to cytosol cation flux through RyR2 channels. Intracellular flecainide or QX-FL, but not NU-FL, reduced Ca(2) (+) spark frequency. CONCLUSIONS AND IMPLICATIONS: Given its inability to block physiologically relevant cation flux through RyR2 channels, and its lack of efficacy in blocking the cytosolic-to-luminal current, the effect of QX-FL on Ca(2) (+) sparks is likely, by analogy with flecainide, to result from Na(+) channel block. Our data reveal important differences in the interaction of flecainide with sites in the cytosolic vestibules of Na(+) and RyR2 channels.

Microwave-Assisted Synthesis of a MK2 Inhibitor by Suzuki-Miyaura Coupling for Study in Werner Syndrome Cells.

Microwave-assisted Suzuki-Miyaura cross-coupling reactions have been employed towards the synthesis of three different MAPKAPK2 (MK2) inhibitors to study accelerated aging in Werner syndrome (WS) cells, including the cross-coupling of a 2-chloroquinoline with a 3-pyridinylboronic acid, the coupling of an aryl bromide with an indolylboronic acid and the reaction of a 3-amino-4-bromopyrazole with 4-carbamoylphenylboronic acid. In all of these processes, the Suzuki-Miyaura reaction was fast and relatively efficient using a palladium catalyst under microwave irradiation. The process was incorporated into a rapid 3-step microwave-assisted method for the synthesis of a MK2 inhibitor involving 3-aminopyrazole formation, pyrazole C-4 bromination using N-bromosuccinimide (NBS), and Suzuki-Miyaura cross-coupling of the pyrazolyl bromide with 4-carbamoylphenylboronic acid to give the target 4-arylpyrazole in 35% overall yield, suitable for study in WS cells.