HCl In EtOH Research Articles

Rapid and Mild Cleavage of Aryl‐Alkyl Ethers to Liberate Phenols

AbstractWe report that the Piers‐Rubinsztajn reaction enables rapid deprotection of aryl alkyl ethers under ambient conditions. This chemistry leverages tris(pentafluorophenyl)borane and silyl hydrides to convert aryl methyl ethers to siloxanes, which can then be cleaved using 1 % HCl in EtOH. We examined 26 derivatives and routinely obtained yields >85 %, even in the presence of sterically demanding groups and complex substrate structures. Other alkyl ethers including ethyl, propyl, isopropyl, tert‐butyl, and benzyl groups were also easily removed.

Ni-Catalyzed Enantioconvergent Coupling of Epoxides with Alkenylboronic Acids: Construction of Oxindoles Bearing Quaternary Carbons

We have developed a nickel- nickel/bisphosphine-catalyzed stereoconvergent cross-coupling reaction of epoxides with alkenylboronic acids. Racemic spiroepoxyoxindoles were converted to chiral homoal...

Synthesis of copper(II) and zinc(II) complexes with chalcone–thiosemicarbazone hybrid ligands: X-ray crystallography, spectroscopy and yeast activity

Four chalcone–thiosemicarbazones (C-TSCs) of the type 2-((E)-3-(4-R-phenyl)-1-phenylallylidene)-N-phenylhydrazinecarbothioamide, where R = Cl (HL1), NO2 (HL2), CH3 (HL3) or CN (HL4), were prepared in good yields from the reaction of the respective chalcone with 4-phenyl-3-thiosemicarbazide and HCl in EtOH. Reaction of HL with CuCl2·2H2O or ZnCl2 in the presence of Et3N afforded the complexes [M(L)2], M = Cu(II) or Zn(II). X-ray diffraction analysis revealed that the ligands coordinate in their deprotonated form, in a bidentate fashion through the iminic nitrogen and sulfur atoms. Yeast activities of the compounds were tested, where the ligand HL4 was the most damaging derivative, exhibiting cell viability at about 50%. On the other hand, lipid peroxidation assays revealed that the ligand HL1 was able to better induce membrane damage compared to the other compounds. It has been found that coordination with Cu(II) and Zn(II) did not increase the biological activities of the C-TSCs.

Isotalatisidine Hemihydrochloride Sesquihydrate from Aconitum talassicum

We continued our study of alkaloids from Aconitum talassicum Popov collected in Kamchik pass (Tashkent Oblast, Uzbekistan). Alkaloids of the plant growing in Uzbekistan have not been previously studied. We studied roots of this plant that were collected after the aerial part had died off. The content of total alkaloids was 2.5% of the dry plant weight [1]. A part (4.2 g) of the total alkaloids was dissolved with heating in Me 2 CO and left at room temperature. The resulting crystals were recrystallized from MeOH to afford talatisamine (0.32 g). The mother liquor was chromatographed over a column of silica gel (KSK, 50:1 adsorbent–substance ratio) with elution by CHCl 3 with gradually added MeOH. Elution by CHCl 3 –MeOH (100:1) isolated 14-O-acetyltalatisamine (0.07 g) and talatisamine (0.19 g). Eluates of CHCl 3 –MeOH (30:1) isolated isotalatisidine (0.08 g) and isoboldine (0.05 g); of CHCl 3 –MeOH (20:1), talatisidine (0.03 g). The mother liquor was evaporated, dissolved in EtOH, and treated until weakly acidic with HCl in EtOH. The EtOH was removed. Work up with Me 2 CO produced a crystalline hydrochloride (0.07 g) that had mp 113–115°C, which was close to that of isotalatisidine hydrate [2], after recrystallization from Me 2 CO. The structure of the isolated hydrochloride was studied by x-ray crystal structure analysis (XSA). It was found that the compound was isotalatisidine hemihydrochloride sesquihydrate. The asymmetric (independent) unit contained two alkaloid molecules (one of which was protonated; the other, as the base and numbered with stroke), three water molecules, and a chloride ion. The conformations of the rings and orientations of the hydroxyls agreed in general with those observed in talatisidine [3] except for the C1 (C1) hydroxyl. This hydroxyl had the -orientation in talatisidine whereas it had the -orientation in isotalatisidine. The -orientation of the C1 hydroxyl led to the formation of an intramolecular H-bond. Although the alkaloid in the ionic form formed a H-bond between the hydroxyl O atom (O1) and the protonated N atom (NH + ), the base (unprotonated molecule) formed one between the -hydroxyl H atom (O1H) and the unshared pair of the N atom (N1). Table 1 presents the parameters of the intramolecular H-bonds in the crystal hydrate. Ring A had the boat

Anti-inflammatory activities and mechanisms of Artemisia asiatica ethanol extract

Ethnopharmacological relevanceArtemisia asiatica Nakai (Compositae) is a representative herbal plant used to treat infection and inflammatory diseases. Although Artemisia asiatica is reported to have immunopharmacological activities, the mechanisms of these activities and the effectiveness of Artemisia asiatica preparations in use are not known. Materials and methodsTo evaluate the anti-inflammatory activities of Artemisia asiatica ethanol extract (Aa-EE), we assayed nitric oxide (NO), tumor necrosis factor (TNF)-α, and prostaglandin E2 (PGE2) in macrophages and measured the extent of tissue injury in a model of gastric ulcer induced in mice by treatment with HCl in EtOH. Putative enzymatic mediators of Aa-EE activities were identified by nuclear fractionation, reporter gene assay, immuoprecipitation, immunoblotting, and kinase assay. Active compound in Aa-EE was identified using HPLC. ResultsTreatment of RAW264.7 cells and peritoneal macrophages with Aa-EE suppressed the production of NO, PGE2, and TNF-α in response to lipopolysaccharide (LPS) and induced heme oxygenase-1 expression. The Aa-EE also ameliorated symptoms of gastric ulcer in HCl/EtOH-treated mice. These effects were associated with the inhibition of nuclear translocation of nuclear factor (NF)-κB and activator protein (AP)-1, implying that the anti-inflammatory action of the Aa-EE occurred through transcriptional inhibition. The upstream regulatory signals Syk and Src for translocation of NF-κB and TRAF6 for AP-1 were identified as targets of this effect. Analysis of Aa-EE by HPLC revealed the presence of luteolin, known to inhibit NO and PGE2 activity. ConclusionThe anti-inflammatory activities attributed to Artemisia asiatica Nakai in traditional medicine may be mediated by luteolin through inhibition of Src/Syk/NF-κB and TRAF6/JNK/AP-1 signaling pathways.

Ions with strong symmetric H-bonds and their solvation in aqueous-ethanolic solutions of HCl

Ion-molecular interactions in the HCl-EtOH-H2O system are studied by means of multiple frustrated total internal reflection IR spectroscopy over a wide range of concentrations of the components. It is demonstrated that, in the investigated solutions, the acid is fully bound into ions and uncharged complexes formed by strong symmetric or quasi-symmetric H-bonds. There is a competition between H2O and EtOH molecules during the formation of the (H5C2(H)O…H…O(H)C2H5)+, (H2O…H…OH2)+, and (H2O…H…O(H)C2H5)+ proton disolvates. In dilute solutions of HCl in 2: 1 and 1: 1 EtOH-H2O mixtures, (H2O…H…OH2)+ proton dihydrates are mainly formed, whereas in concentrated HCl solutions, under conditions of a partial solvation of ions by solvent molecules, predominantly (H2O…H…O(H)C2H5)+ mixed proton disolvates arise. In concentrated solutions of HCl in EtOH with low water content, the acid is partially bound into (H5C2(H)O…H+…Cl−) uncharged complexes with the participation of the Cl− anion.

Facile regioselective synthesis of novel bioactive thiazolyl-pyrazoline derivatives via a three-component reaction and their antimicrobial activity

A series of novel 2-(3,5-diphenyl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles have been prepared by a three-component cyclo-condensation of various chalcones, thiosemicarbazide and phenacyl bromide. The easy work-up of the products, rapid reaction, and mild conditions are notable features of this protocol. The reaction was efficiently catalyzed in one-pot by a few drops of HCl in EtOH under reflux conditions providing the title compounds in moderate to high yields. The antibacterial activity of the selected products was examined. Some products exhibit promising activities.

Optimization for the anthocyanin extraction from purple sweet potato roots, using response surface methodology.

Huang, C. L., W. C. Liao, C. F. Chan, and Y. C. Lai. 2010. Optimization for the anthocyanin extraction from purple sweet potato roots, using response surface methodology. J. Taiwan Agric. Res. 59:143–150. Anthocyanins were successfully extracted from ‘TNG 73’ purple sweet potato roots by using acidic-ethanol extraction. Three extraction parameters including HCl concentration, extraction time, and temperature were evaluated. Response surface methodology (RSM), an effective statistical technique was applied to establish a regression model. The coefficients of the regression model were calculated and used to predict the extraction performance and determine the optimal operating conditions. In conclusion, the optimal conditions for the ‘TNG 73’ anthocyanin extraction were determined to be 12% HCl (1.5 N HCl in EtOH), 45 min, and 50℃.

Preparation and Structural Elucidation of the Picolinyl Ester of Aldosterone for Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

Treatment of aldosterone with 35% HCl in EtOH or in MeOH followed by the picolinyl derivatization gave the picolinyl derivative of aldosterone-ethyl ether, 8, or methyl ether, 9, as a single and well-shaped liquid chromatographic peak. Picolinyl derivatization of aldosterone produced 21-picolinyl derivative of 18,20-anhydro-hemiacetal derivatives, 6, with poor chromatographic peak with wide half-width. Further conversion of 6 to 8 required long reaction time (>4 h). Structure of each picolinyl or alkyl ether-picolinyl derivative, was carefully elucidated by nuclear magnetic resonance spectroscopy, electron ionization mass spectrometry and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Enhancement of sensitivity (approximately 10-fold) in positive-LC-ESI-MS/MS of aldosterone was confirmed by the use of the alkyl ether-picolinyl derivatization when compared to the underivatized molecule.

Regioselective Protection at N-2 and Derivatization at C-3 of Indazoles

Indazoles are regioselectively protected at N-2 by a 2-(trimethylsilyl)ethoxymethyl (SEM) group using novel conditions. The SEM group can efficiently direct regioselective C-3 lithiation, and the resulting nucleophile can react with a wide range of electrophiles to generate novel indazole derivatives. The SEM group can be removed by treatment with TBAF in THF or aqueous HCl in EtOH.

Envirocat EPZ10: A Recyclable Solid Acid Catalyst for the Synthesis of Biginelli‐Type 3,4‐Dihydropyrimidin‐2(1H)‐ones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Envirocat EPZ10: A Recyclable Solid Acid Catalyst for the Synthesis of Biginelli-type 3,4-Dihydropyrimidin-2(1H)-ones

In refluxing toluene, EPZ10 was found to be the mostreactive among three catalysts, giving the product in 84%isolated yield within 6 h. In contrast, the classical Biginellicondition (cat. HCl in EtOH, reflux, 18 h) gave 80% yield.The solvent effect was studied in the case of EPZ10-catalyzed reaction (Table 1). Clearly, toluene was a muchbetter solvent than other solvents tested in terms of yields.Lower boiling solvent (dichloromethane), protic solvent(EtOH) and Lewis basic solvents (THF, CH

Synthesis of aliphatic 1,2-bishydroxylamines from 1,3- dihydroxyimidazolidines.

Reduction of l-hydroxy-3-imidazoline-3-oxides with NaBH4 gives 1,3-dihydroxyimidazolidines. The latter on subsequent treatment with NH2OH · HCl in EtOH or in hydrochloric acid afford 1,2-bishydroxylamines. An X-ray study of 1,2-bishydroxylaminocycloalkanes has shown them to becis-configurated.

Site-specific bromination of aromatic compounds: a rapid method for radiobromine labelling

[82 Br]bromobenzene and [82Br]-p-bromoanisole have been synthesized in less than 5 min by treatment of the aryltin derivative with ammonium [82Br]bromide, chloramine-T, and HCl in EtOH–H2O at 0 °C.

Boron trifluoride-catalysed rearrangements of some tetrasubstituted neotriterpene epoxides—I

The treatment of A′-neogammacer-17(21)-ene oxide ( 1a) with BF 3·Et 2O complex in CHCl 3 produces entirely different results from those obtained when the same epoxide is treated with HCl in EtOH: while the protic acid converts the compound into the 15,17(21)-diene ( 2a), the Lewis acid produces rearrangements in the carbon skeleton, with formation of the 28-nor-21α-methyl-12,17-diene ( 3a) and of the 22,29,30-trisnor-17α-isopropyl-21-one ( 4a). The structurally similar 19β,28-epoxy-A-neo-18α-olean-3(5)-ene oxide ( 1b) behaves in a completely analogous manner.

The Continuous Process of Ethylsilicate Manufacture

A continuous process of manufacturing Ethylsilicate (Si (OEt) 4) from EtOH and Tetrachlorosilane (SiCL4) was developed.This reaction is the rapidly consecutive reaction, remarkably exothermic, and generating a large quantity of HCL. Furthermore, the formation of the byproduct (polysilicate) increases when the reaction temperature rises above 0°C, and therefore there must be rigid control of the reaction temperature. From thermodynamic calculation, it was concluded that the calolification in the reaction was almost all caused by the heat of the solution of HCl in unreacted EtOH. When EtOH containing the suitable quantity of HCl is used, the calolification in reaction is not evolved.Basing upon this conclusion, the continuous process was developed and carried out on a small pilot plant scale using EtOH-HCl. Reactor consisted of two stages, the first was a jet pump, and the second a stirred tank.Data showing the effect of flow ratio (EtOH/SiCl4) and concentration of HCl in EtOH on the yields of Si (OEt) 4 were presented. From these results, the optimum condition was determined and the cost of production of this continuous process compared with that of the former batch process.