Reagent System Research Articles

Design, synthesis and cytotoxic activity of new 6-O-aroyl (−)-cleistenolide derivatives

Fifteen new analogues of (−)-cleistenolide (1) with aromatic ester groups at the C-6 position were designed and synthesized by multistep sequences. Steglich esterification of δ-pyrone 10 with selected aromatic acids (benzoic, cinnamic, and 4-substituted cinnamic acids) gave the corresponding 6-O-acyl derivatives 11–15. An original method was developed for the selective conversion of the primary benzyloxy group into the corresponding acetoxy function, giving five new bioisosteres (16–20) for biological testing. Finally, the dibenzyl derivative 11 was converted to the corresponding diacetate 2 using the AcBr/Zn(OTf)2 reagent system. For the transformation of compounds 12–15 into the corresponding 4,7-diacetates (3–6), in addition to Zn(OTf)2, it was necessary to use FeCl3 as a co-catalyst. The cleistenolide analogues thus obtained were tested for their in vitro antitumour activity The majority of compounds showed higher potency compared to lead 1 toward five of six investigated human tumour cell lines, but were almost completely inactive in the culture of normal foetal fibroblasts (MRC-5). The most potent antiproliferative activity was shown by 4,7-di-O-benzyl derivatives 13 and 14, with IC50 values of 0.04 (HeLa) and 0.09 μM (Jurkat), respectively. Preliminary SAR analysis revealed some of the structural features important for the activity of this class of compounds. These are: the presence of unsubstituted cinnamate function at the C-6 position and the presence of an acetoxy group at the C-4 position.

NCBSI/KI: A Reagent System for Iodination of Aromatics through In Situ Generation of I-Cl.

In situ iodine monochloride (I-Cl) generation followed by iodination of aromatics using NCBSI/KI system has been developed. The NCBSI reagent requires no activation due to longer bond length, lower bond dissociation energy, and higher absolute charge density on nitrogen. The system is adequate for mono- and diiodination of a wide range of moderate to highly activated arenes with good yield and purity. Moreover, the precursor N-(benzenesulfonyl)benzenesulfonamide can be recovered and transformed to NCBSI, making the protocol eco-friendly and cost-effective.

Room-temperature stable loop-mediated isothermal amplification (LAMP) reagents to detect leptospiral DNA.

Loop-mediated isothermal amplification (LAMP) is one of the most promising tools for rapidly detecting Leptospira spp. However, LAMP is hampered by cold storage to maintain the enzymatic activity of Bst DNA polymerase. To overcome the drawback of cold storage requirement for LAMP reagents we modified the reagents by adding sucrose as stabilizer. We then sought to determine the stability at room temperature of the premixed LAMP reagents containing sucrose. Premixed LAMP reagents with sucrose and without sucrose were prepared. The prepared mixtures were stored at room temperature for up to 60 days, and were subjected to LAMP reactions at various intervals using rat kidney samples to detect leptospiral DNA. The premixed LAMP reagents with sucrose remained stable for 45 days while sucrose-free premixed LAMP reagents showed no amplification from day 1 of storage at room temperature up to day 14. The LAMP reagent system can be refined by using sucrose as stabilizer, thus allowing their storage at room temperature without the need for cold storage. The modified method enables greater feasibility of LAMP for field surveillance and epidemiology in resource-limited settings.

The flotation separation of sphalerite from pyrite through a novel flotation reagent system of FeCl3-CuSO4-aminotriazolethione

To reduce the consumption of lime in mineral processing means reducing CO2 emission. Herein, a novel FeCl3-CuSO4-APTT (4-amino-5-pentyl-1,2,4-triazole-3-thione) approach was first developed to replace the common CaO-CuSO4-xanthate technology during flotation separation of sphalerite from pyrite. APTT exhibited a stronger collecting power towards pyrite than sphalerite, while the attendance of ferric chloride significantly depressed the floatability of pyrite and sphalerite, and its inhibition against pyrite was stronger than that to sphalerite. The addition of cupric sulfate not only removed the inhibition of ferric chloride against sphalerite, but also promoted its floatability. Nevertheless, the floatability of the FeCl3-depressed pyrite was hardly recovered by cupric sulfate. Using FeCl3 as the depressor against pyrite and CuSO4 as the activator for sphalerite, APTT realized a selective and efficient flotation recovery of sphalerite from pyrite in the weakly-acidic medium. FTIR (Fourier Transform Infrared Spectroscopy) and contact angle indicated that the pretreatment with FeCl3 and CuSO4 in sequence significantly weakened APTT adsorption on pyrite, while benefited sphalerite adsorption towards APTT, resulting in creating a dramatical difference of surface hydrophobicity and flotation recovery between the two minerals. XPS (X-ray photoelectron spectroscopy) elucidated that after modifying sphalerite surface successively through FeCl3, CuSO4 and APTT, the Cu-APTT complexes were detected on sphalerite, which were of significance to hydrophobizing its flotation.

Synthesis of [1,4]Thiazino[4,3-a]indol-10-one Derivatives through Radical Anti Aza-Michael Addition of 2′-Aminochalcones

An efficient method for the synthesis of [1,4]thiazino[4,3-a]indole derivatives using sodium chlorodifluoroacetate (ClCF2CO2Na) and elemental sulfur as the difluoromethylthiolating reagent system has been developed. Three-component reactions of 2'-aminochalcones, sulfur, and ClCF2CO2Na under basic conditions using TEMPO as the oxidant afforded [1,4]thiazino[4,3-a]indol-10-ones containing a difluoromethyl thioether moiety in good yields. Four bonds including one C-N, two C-S, and one C-C bonds are selectively formed in the sequential transformation process.

Determination of class G antibodies to SARS-CoV2 after application of ‘GamCOVID-Vac’ or ‘Sputnik V’ vaccine of National Research Centre for Epidemiology and Microbiology n.a. honorary academician N.F. Gamaleya

We conducted a laboratory examination of 83 people after vaccination against the new coronavirus with the use of the ‘Gam-COVID-Vac’ vaccine of National Research Centre for Epidemiology and Microbiology n.a. honorary academician N.F. Gamaleya (Moscow, Russia), in order to determine the presence of post-vaccination class G antibodies to SARS-CoV-2. The reagent system ‘SARS-CoV-2-IgG – ELISA-BEST’ (Vector-Best Co., Novosibirsk, Russia) was used. According to the manufacturer, the reagent system detects a pool of class G immunoglobulins synthesized to all antigenic determinants of protein S, including the RBD domain, which ensures the specificity of this method for assessing the post-vaccination immune response. The study involved 36 men and 47 women, with an average age of 48.40 ± 1.15 years. An interim analysis of the blood serum of 51 participants 21 days after the first dose of the vaccine showed the presence of IgG antibodies to SARS-CoV-2 in 45 (88.24%) people. After 42 days, all 83 (100%) people were found to have IgG antibodies to SARS-CoV-2 virus. It is advisable to continue the study to assess the dynamics of the level of postvaccinal antibodies for 6 months.

Treatment of Secondary Post-Transplant Engraftment Failure with Donor CD34+ Enriched, T-Cell Depleted Peripheral Blood Stem Cells Isolated By the Clinimacs® System

Introduction: Secondary engraftment failure after hematopoietic stem cell transplant (HSCT) is characterized by pancytopenia and 1-year mortality reported to reach as high as 75% (1) secondary to infectious and bleeding complications. It is frequently associated with treatment of CMV reactivation. Reinfusion of a second graft from the original donor is the preferred treatment but carries the risk of graft versus host disease (GVHD) given high T lymphocyte graft content. The CliniMACS® CD34 reagent system permits in vitro selection and enrichment of CD34+ cells from heterogeneous hematologic cell populations and is used for T cell depletion of HSCT. We report the results of a pilot study of infusion of CD34+ selected stem cell boost for treatment of post-transplant secondary engraftment failure.Methods: Eligible patients were 0 - 80 years of age, treated with a prior HSCT and diagnosed with secondary engraftment failure (defined as a decrease in donor chimerism by ≥ 50%) or incomplete graft function (anemia ≤8g/dL or transfusion dependent; neutropenia ≤1000/mcl or requiring growth factor support; thrombocytopenia ≤20,000/mcl or transfusion dependent). Subjects were excluded if the original donor was not available or if they had reversible causes for engraftment failure, including active viral infections, continued use of myelosuppressive medications or uncontrolled acute or chronic GVHD. Once collected, peripheral blood stem cell (PBSC) donor grafts were processed using the CliniMACS® System and CD34 reagent to enrich CD34+ cell content and decrease CD3+ cell content. After enrichment, the product was considered acceptable for infusion if CD34+ cell content was ≥ 1x106 cells/kg and CD3+ content was ≤ 5x104 cells/kg. The CD34+ enriched stem cell boost was infused without a preceding conditioning regimen.Results: 10 patients were enrolled; median age was 53.5 years (range 7 - 69), 6 patients were male. Diagnoses included: aplastic anemia (n=1), acute lymphoblastic leukemia (n=1), acute myeloid leukemia (n=3), myelodysplastic syndrome (n=2) and non-Hodgkin lymphoma (n=3). The original graft source was PBSC from a matched related donor (MRD) in 3 subjects, matched unrelated donor in 6 cases, and one haploidentical related donor. GVHD prophylaxis included tacrolimus and methotrexate (n=8), tacrolimus, methotrexate and mycophenolate (n=1); one subject did not receive GVHD prophylaxis as part of a T cell depleted transplant. Eight patients had resolved or controlled GVHD. Median donor chimerism before engraftment failure was 98% (range 96 - 100).The cause of engraftment failure was known in 5 cases (irreversible medication toxicity [n=3], recurrence of aplastic anemia [n=1], viral infection [n=1]). Median time to diagnosis of secondary engraftment failure was 4 months (range 2-21). Median donor chimerism before boost was 2.5% (range 0-91%). Neutrophil engraftment failure was present in 6 patients; red blood cell (RBC) and platelet engraftment failure was present in 8 patients. Median time from transplant to boost infusion was 7.5 months (range 2-27)Median infused CD34+ cell dose was 3.15 x 106 CD34+ cells/kg (range1.67-10.9); median CD3+ cell dose was 1.9 x 103 CD3+ cells/kg (range 1.43 - 26.2). There were no infusion reactions and all patients tolerated the procedure without adverse events. Thirty days after boost infusion, 7 subjects (70%) had resolution of their cytopenias, 1 patient had platelet engraftment but remained dependent on RBC transfusions and 2 did not respond. We observed 2 cases of recurrence of GVHD; in both cases, the recurrence was at a lower grade than before the boost infusion. One responsive patient presented subsequent engraftment failure after boost (refractory aplastic anemia). Five patients remain alive at a median of 37 months after CD34+ enriched stem cell boost, with 1 - year estimated survival of 56%.Conclusions: Secondary engraftment failure can be safely and effectively treated with infusion of a CD34-enriched boost using the CliniMACS® System.Davies SM, Weisdorf DJ, Haake RJ, et al. Second infusion of bone marrow for treatment of graft failure after allogeneic bone marrow transplantation. Bone Marrow Transplant 1994;14:73-7. DisclosuresCaimi:Abbvie: Equity Ownership; Incyte: Equity Ownership; Seattle Genetics: Equity Ownership; Celgene: Speakers Bureau. Malek:Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau. Cooper:Novartis: Research Funding. de Lima:Celgene Corporation: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees.

NbCl5-Mg Reagent System in Regio- and Stereoselective Synthesis of (2Z)-Alkenylamines and (3Z)-Alkenylols from Substituted 2-Alkynylamines and 3-Alkynylols.

The reduction of N,N-disubstituted 2-alkynylamines and substituted 3-alkynylols using the NbCl5–Mg reagent system affords the corresponding dideuterated (2Z)-alkenylamine and (3Z)-alkenylol derivatives in high yields in a regio- and stereoselective manner through the deuterolysis (or hydrolysis). The reaction of substituted propargylamines and homopropargylic alcohols with the in situ generated low-valent niobium complex (based on the reaction of NbCl5 with magnesium metal) is an efficient tool for the synthesis of allylamines and homoallylic alcohols bearing a 1,2-disubstituted double bond. It was found that the well-known approach for the reduction of alkynes based on the use of the TaCl5-Mg reagent system does not work for 2-alkynylamines and 3-alkynylols. Thus, this article reveals a difference in the behavior of two reagent systems—NbCl5-Mg and TaCl5-Mg, in relation to oxygen- and nitrogen-containing alkynes. A regio- and stereoselective method was developed for the synthesis of nitrogen-containing E-β-chlorovinyl sulfides based on the reaction of 2-alkynylamines with three equivalents of methanesulfonyl chloride in the presence of stoichiometric amounts of niobium(V) chloride and magnesium metal in toluene.

A Stereocontrolled Synthesis of a Phosphorothioate Cyclic Dinucleotide-Based STING Agonist.

We describe a stereodefined synthesis of the newly identified non-natural phosphorothioate cyclic dinucleotide (CDN) STING agonist, BMT-390025. The new route avoids the low-yielding racemic approach using P(III)-based reagents, and the stereospecific assembly of the phosphorothioate linkages are forged via the recently invented P(V)-based platform of the so-called PSI (Ψ) reagent system. This P(V) approach allows for the complete control of chirality of the P-based linkages and enabled conclusive evidence of the absolute configuration. The new approach offers robust procedures for preparing the stereodefined CDN in eight steps starting from advanced nucelosides, with late-stage direct drop isolations and telescoped steps enabling an efficient scale-up that proceeded in an overall 15% yield to produce multigram amounts of the CDN.

Dry Reagent Tests in the 1880s-Dr Pavy's Pellets and Dr Oliver's Papers.

In the 1880s, concern over the inconvenience of hazardous chemical solutions used for bedside urinalysis sparked an interest in the development of dry reagents for a range of common urine tests. This article examines the history of Dr Pavy's Pellets and Dr Oliver's Papers, 2 different dry reagent systems developed in the 1880s for bedside urine testing. It sets these developments in the context of the earlier dry chemistry work (e.g., indicator papers) and the subsequent work that led to modern day reagent tablets and dipstick devices. Tests based on dry reagents can be traced back to the 1st century, but active development, in the form of indicator papers, dates from the 1600s. In the 1880s, spurred by dissatisfaction with liquid-based bedside urine testing among clinicians, Dr Frederick William Pavy and Dr George Oliver developed dry reagent tests, based on pellets (Dr Pavy's Pellets) and chemically impregnated papers (Dr Oliver's Papers) for urine sugar and urine albumin. These reagents were commercialized by a number of companies and provided in convenient cases (Physician's Pocket Reagent Case). Eventually, these tests lost popularity and were replaced by the type of tablets and dipsticks developed by both Eli Lilly, and the Ames Division of Miles Laboratories (subsequently Bayer, and currently Siemens Healthineers) during the 1940s and 1950s.

Lewis Acid/Oxidant as Rapid Regioselective Halogenating Reagent System for Direct Halogenation of Fused Bi‐/Tri‐cyclic Hetero‐Aromatic Congeners via−H bond Functionalization

AbstractHerein, we report the identification of new and fast halogenating reagent system consisting of Lewis acid AlX3 [X=Cl, Br, I] as a halogen source in the presence of tert‐butyl hydroperoxide (TBHP) which has been utilized for the direct regioselective halogenation on various fused bi‐/tri‐cyclic hetero‐aromatic congeners 3 a–q, 7 a–d, 8 and 9 via −H bond functionalization. The operationally simple protocol is quite fast and does not require the external halogenation source at 110 °C in 20–60 minutes and furnished halogenated fused heterocycles 4 a–p, 5 a–k, 6 a–l, 10 a–i, 11 a, 12 a–b in up to 96% yields. The gram‐scale synthesis, wide substrate scope, functional group tolerance, control experiments and application to further derivatization/functionalization for C−C bond formation further highlights the versatility of the developed methodology as well as the compatibility of the new catalyst. The combination of Lewis acid (AlX3) as a halogen source and TBHP (oxidant) as a halogenating reagent system is the first account for the direct regioselective halogenation of several fused bi‐/tri‐cyclic hetero‐aromatic congeners via −H bond functionalization.

Universal Engraftment after Allogeneic Hematopoietic Cell Transplantation Using Cryopreserved CD34-Selected Grafts

As a result of the COVID-19 pandemic, most centers performing allogeneic hematopoietic cell transplantation (allo-HCT) have switched to the use of cryopreserved grafts. Previous investigators have suggested that cryopreserved allografts may heighten risk of nonengraftment. To date, no study has investigated the effect of cryopreservation of CD34-selected hematopoietic progenitor cells (CD34+ HPCs) used as the sole graft source. In this study, we sought to evaluate outcomes after unrelated donor or matched sibling allo-HCT with cryopreserved CD34+ HPCs. This was a single-center analysis of adult patients with hematologic malignancies who underwent allo-HCT with cryopreserved CD34-selected allo-HCT grafts between January 2010 and June 2017. All patients received ablative conditioning and antirejection prophylaxis with rabbit antithymocyte globulin. G-CSF-mobilized leukapheresis products underwent CD34 selection using the CliniMACS Reagent System. Cells were then cryopreserved in DMSO (final concentration 7.5%) to -90 °C using a controlled-rate freezing system before being transferred to vapor-phase liquid nitrogen storage. In internal validation, this method has shown 92% mean CD34+ cell viability and 99.7% mean CD34+ cell recovery. Engraftment was defined as the first of 3 consecutive days of an absolute neutrophil count of ≥0.5. Platelet recovery was recorded as the first of 7 consecutive days with a platelet count ≥20 K/μL without transfusion. Kaplan-Meier methodology was used to estimate overall survival (OS) and relapse-free survival (RFS), and cumulative incidence functions were used to estimate rates of relapse, nonrelapse mortality (NRM), and acute graft-versus-host disease (GVHD). A total of 64 patients received a cryopreserved CD34-selected graft. The median CD34+ cell count before cryopreservation was 6.6×106/kg (range, 1.4 to 16.1×106/kg), and the median CD3+ cell count was 2.0×103/kg (range, 0 to 21.1×106/kg). All patients were engrafted, at a median of 11 days post-HCT (range, 8 to 14 days). One patient had poor graft function in the setting of cytomegalovirus viremia, necessitating a CD34-selected boost on day +57. The median time to platelet recovery was 16 days (range, 13 to 99 days). The estimated 2-year OS was 70% (95% confidence interval [CI], 58% to 83%) with cryopreserved grafts versus 62% (95% CI, 57% to 67%) with fresh grafts (hazard ratio [HR], 0.86; 95% CI, 0.54 to 1.35; P=.5). The estimated 2-year RFS in the 2 groups was 59% (95% CI, 48% to 74%) versus 56% (95% CI, 51% to 61%; HR, 1.01; 95% CI, 0.68 to 1.51; P > .9). The cumulative incidence of relapse at 2 years was 29% (95% CI, 17% to 41%) versus 23% (95% CI, 19% to 27%; P=.16), and the cumulative incidence of NRM at 2 years was 17% (95% CI, 9% to 28%) versus 23% (95% CI, 19% to 28%; P=.24). The cumulative incidence of grade II-IV acute GVHD by day +100 was 16% with cryopreserved grafts (95% CI, 8% to 26%) and 16% (95% CI, 13% to 20%; P=.97) with fresh grafts. Moderate to severe chronic GVHD by day +365 occurred in only 1 recipient of a cryopreserved graft (2%). Our data show that in patients with hematologic malignancies who received cryopreserved allogeneic CD34+ HPCs, engraftment, GVHD, and survival outcomes were consistent with those seen in recipients of fresh allogeneic CD34+ HPC grafts at our center. Our laboratory validation and clinical experience demonstrate the safety of our cryopreservation procedure for CD34-selected allografts.

Rosiglitazone alleviates lipopolysaccharide-induced inflammation in RAW264.7 cells via inhibition of NF-κB and in a PPARγ-dependent manner.

Rosiglitazone is a synthetic peroxisome proliferator-activated receptor (PPAR)γ agonist widely used for the treatment of type 2 diabetes. Recent studies have demonstrated that rosiglitazone displays anti-inflammatory effects. The present study aimed to investigate whether rosiglitazone alleviates decreases in RAW264.7 cell viability resulting from lipopolysaccharide (LPS)-induced inflammation, as well as exploring the underlying mechanism. A macrophage inflammatory injury model was established by treating RAW264.7 cells with 100 ng/ml LPS. Cells were divided into LPS and rosiglitazone groups with different concentrations. Cell viability was assessed by performing an MTT assay. The expression of inflammatory cytokines was detected by conducting enzyme-linked immunosorbent assays and reverse transcription-quantitative PCR. Nitric oxidesecretion was assessed using the Griess reagent system. The expression levels of key nuclear factor-κB pathway-associated proteins were detected via western blotting. Rosiglitazone alleviated LPS-induced decrease in RAW264.7 cell viability and inhibited inflammatory cytokine expression in a concentration-dependent manner. Rosiglitazone significantly inhibited LPS-induced upregulation of p65 phosphorylation levels and downregulated IκBα expression levels. However, rosiglitazone-mediated inhibitory effects were reversed by PPARγ knockdown. The results of the present study demonstrated that rosiglitazone significantly inhibited LPS-induced inflammatory responses in RAW264.7 macrophage cells, which was dependent on PPARγ activation and NF-κB suppression.

Optical-Switch-Enabled Microfluidics for Sensitive Multichannel Colorimetric Analysis.

The implementation of colorimetric analysis within microfluidic environments engenders significant benefits with respect to reduced sample and reagent consumption, system miniaturization, and real-time measurement of flowing samples. That said, conventional approaches to colorimetric analysis within microfluidic channels are hampered by short optical pathlengths and single-channel configurations, which lead to poor detection sensitivities and low analytical throughputs. Although the use of multiplexed light source/photodetector modules allows for multichannel analysis, such configurations significantly increase both instrument complexity and cost. To address these issues, we present a four-channel colorimetric measurement scheme within an optical-switch-enabled microfluidic chip (OSEMC) fabricated by two-photon stereolithography. The integration of optical switches enables sequential signal readout from each detection channel, and thus, only a single light source and a photodetector are required for operation. Optical switches can be controlled in a bespoke manner by changing the medium in the switch channel between a "light-transmitting" fluid and a "light-blocking" fluid using pneumatic microvalves. Such optical switches are characterized by fast response times (approximately 200 ms), tunable switching frequencies (between 0.1 and 1.0 Hz studied), and excellent stability. Operational performance demonstrates both good sensitivity and reproducibility through the colorimetric analysis of nitrite and ammonium samples using four detection channels. Furthermore, the use of OSEMC for parallel and real-time analysis of flowing samples is investigated via characterization of the adsorption kinetics of tartrazine on activated charcoal and the catalytic reaction kinetics of horseradish peroxidase (HRP).

Biological Response Induced in Primary Human Gingival Fibroblasts upon Exposure to Various Types of Injectable Astringent Retraction Agents.

Traditional chemo-mechanical retraction/displacement materials can impact the gingival margin tissues. This study was undertaken to analyze biological responses induced in human gingival fibroblasts (HGFs) upon application of injectable astringent-based agents used in the cordless retraction technique. HGFs were exposed to hemostatic agents (five gels, three pastes, and one foam) based on aluminium chloride, aluminium sulphate and ferric sulphate. Changes in cell viability and proliferation were evaluated using an MTT assay and a BrdU assay. The cytoskeleton structure organization (zyxin and F-actin) was visualized by confocal laser scanning microscopy. Oxidative stress was determined using the Griess Reagent System. The RNA expression levels of antioxidant enzymes were quantified by real-time RT-PCR. The statistical significance was evaluated using Student’s t-test and one-way ANOVA with post-hoc Tukey HSD test. The evaluated agents did not downregulate fibroblast viability or proliferation. No significant cytoskeleton reorganization was observed. Only one agent (Expasyl) induced oxidative stress, demonstrated by the increased level of nitrites. Incubation with the studied agents significantly increased the RNA expression of some antioxidant enzymes (SOD1, SOD3, GPX1). However, no significant influence on the expression of SOD2 and HMOX1 was detected. The injectable forms of chemical retraction agents revealed biocompatibility with HGFs, suggesting their potential clinical usefulness in gingival margin retraction.

Metal‐free Catalytic Esterification of Aryl Alkyl Ketones with Alcohols via Free‐radical Mediated C(sp3)−H Bond Oxygenation

AbstractA novel metal‐free catalytic one‐pot approach has been developed for the esterification of aralkyl ketones with alcohols under open‐air atmospheric conditions. The inexpensive iodide/oxone reagent system allowed the cascade C(sp3)−H bond oxygenation, selective C−C bond cleavage and esterification through the both radical and ionic pathways in a stepwise manner in one‐pot. This mild, convenient and economically viable catalytic method tolerates the various functional groups to provide the corresponding alkyl benzoates in up to 98% yields with up to 99% selectivity. The efficiency and feasibility of scale‐up of the present catalytic system was demonstrated with gram scale experiments (up to 10 gram scale).

Metal‐, Photocatalyst‐, Light‐ and Electrochemical‐Free C‐3 Trifluoromethylation of Quinoxalin‐2(1H)‐ones, Imidazo[1,2‐a]pyridines and 2H‐Indazoles

AbstractWe report an efficient protocol for the synthesis of 3‐trifluoromethylquinoxalin‐2(1H)‐ones, 3‐trifluoromethylimidazo[1,2‐a]pyridines and 3‐(trifluoromethyl)‐2H‐indazoles under metal‐, photocatalyst‐, light‐ and electrochemical‐free conditions. The combination of Langlois’ reagent (sodium triflinate) with the oxidant (NH4)2S2O8 in DMSO: H2O (10 : 1) works as an efficient reagent system to promote this free radical trifluoromethylation reaction. The trifluoromethyl radical generated by the oxidation of sodium triflinate with (NH4)2S2O8 attacks on to the C‐3 position of quinoxalin‐2(1H)‐ones, imidazo[1,2‐a]pyridines and 2H‐indazoles; and the excess SO4•− completes the reaction furnishing their respective 3‐trifluoromethyl derivatives in very good to excellent yields. Radical scavenging experiments with (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO), butylated hydroxy toluene (BHT), and 1,1‐diphenylethylene also prove the participation of radical.

Polypropylene foams under CO2 batch conditions: From formulation and rheological modeling to cell-growth simulation

The objective of this work was to study the development of polypropylene (PP) foams with low density (<100 kg m−3) using a CO2 batch process. To carry out this study, we used a PP-g-MA that was chemically modified by reactive extrusion to obtain polymer branched structures. Two reagent systems were selected on the basis of chemical reactions with maleic anhydride—the first one is based on the reaction between maleic anhydride and primary amines (MA/NH2, triamine, Jeffamine T-403), and the second one is based on ionic interactions from Zn neutralization. Both of these systems have shown that it is possible to obtain branched PP structures favorable to CO2 foaming and were compared to a commercial, high-melt-strength PP.We have shown that the branched structure of polymer chains can be defined on the basis of a rheological criterion. It defines the notion of fractal behavior (coupling of relaxation modes), which polymer chains must have for nonlinear behavior (strain hardening). This criterion has been defined by analogy with the sol-gel transition, tan δ = 1.Finally, in terms of modeling and simulation, the plasticizing effect of CO2 was modeled from the experimental rheological behavior of the PP plasticized with synthetic oil. A theoretical power law was derived and was then introduced in the mass balance equations to predict the cell growth during depressurization.

Aluminium chloride-potassium iodide-acetonitrile system: A mild reagent system for aromatic claisen rearrangement at ambient temperature

Claisen rearrangement is used as the standard methods for the generation of complex organic substance. It is one of the well-known methods for the introduction of carbon-carbon bond. We have developed a protocol using allyl aryl ether as a substrate and AlCl3-KI as a mild reagent system and acetonitrile (CH3CN) is taken as solvent at ambient temperature. The reagent system presented in this current work is found to be appropriate for Claisen rearrangement of several aromatic alcohols with excellent yields.

Acyl Fluorides from Carboxylic Acids, Aldehydes, or Alcohols under Oxidative Fluorination.

We describe a novel reagent system to obtain acyl fluorides directly from three different functional group precursors: carboxylic acids, aldehydes, or alcohols. The transformation is achieved via a combination of trichloroisocyanuric acid and cesium fluoride, which facilitates the synthesis of various acyl fluorides in high yield (up to 99%). It can be applied to the late-stage functionalization of natural products and drug molecules that contain a carboxylic acid, an aldehyde, or an alcohol group.