Tosyl Group Research Articles

Preparation and dielectric relaxation of a novel ionocellulose derivative

A new water-soluble ionocellulose material bearing imidazolium tosylate groups was synthesized in a two-step sequence from cellulose, and the electrical conduction properties of this bio sourced polyelectrolyte were investigated. First, tosylcellulose was prepared from neat cellulose and tosyl chloride in the ionic liquid 1-Butyl-3-methylimidazolium chloride [BMIM]Cl. Then, the ionocellulose containing imidazolium tosylate grafts was synthesized by reacting tosylcellulose and 1-methylimidazole. Both tosylcellulose and ionocellulose were characterized by different analytical techniques including elemental analysis, 13C NMR and FT-IR spectroscopy as well as thermogravimetric analysis. We then compared the dielectric relaxation of neat cellulose with ionocellulose. For both samples, two secondary relaxations were identified at low temperature. These two relaxations became faster in ionocellulose containing imidazolium tosylate grafts. At higher temperatures (T > room temperature), the conductivity is markedly dominated by ionic motions. This work opens new perspectives for preparing a new category of ionocellulose derivatives which are expected to find applications in energy storage technologies and for the elaboration as novel high-performance film dielectric capacitors.

Catalytic Synthesis of Dibenzazepines and Dibenzazocines by 7‐Exo‐ and 8‐Endo‐Dig‐Selective Cycloisomerization

AbstractThe 7‐exo‐ and 8‐endo‐dig‐selective gold‐catalyzed cycloisomerizations of 2‐propargylamino biphenyl derivatives were developed. The reaction of terminal alkynes gave dibenzo[b,d]azepines by 7‐exo‐dig cycloisomerization. In contrast, when internal alkynes were subjected to the reaction, 8‐endo‐dig cycloisomerization proceeded to provide dibenzo[b,d]azocines. The nucleophilicity at the reaction site and the electron‐withdrawing effect of a tosyl group were important for the present selective transformation. This protocol could be used for ynamide substrates and a silver‐catalyzed reaction gave 7‐exo‐dig products selectively.

Nucleophilic Displacement Reaction on Tosyl Cellulose by L-Methionine to the Synthesis of Novel Water-Soluble Cellulose Derivative and Its Antibacterial Activity

A novel ampholytic cellulose derivative, cellulose-L-methionine, has been synthesized by means of an esterification reaction of microcrystalline cellulose with tosyl chloride (p-TsCl) in DMAc/LiCl (8%) at 8°C that was followed by nucleophilic displacement (SN) of the tosyl group by the L-methionine amino acid. The resulting structure of cellulose-L-methionine has been characterized by elemental analysis (CHNSO), Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and scanning electron microscopy (SEM). The antibacterial activity of the synthesized product was screened against Gram-positive and Gram-negative microbial strains such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, by the agar well diffusion method, and compared with commercial antibiotics such as ampicillin and chloramphenicol. It was found that antibacterial experiment revealed excellent antibacterial activity of the cellulose-methionine with respect to a minimal inhibitory concentration (MIC) reference.

Catalytic, Regioselective Sulfonylation of Carbohydrates with Dibutyltin Oxide under Solvent-Free Conditions

A simple approach was developed for the solvent-free regioselective functionalization of carbohydrate polyols with 4-toluesulfonyl (tosyl) group, allowing the easy and quick activation of a saccharide site with a tosylate leaving group. The method is based on the use of catalytic dibutyltin oxide and tetrabuylammonium bromide (TBAB), and a moderate excess of N,N-diisopropylethyl amine (DIPEA) and tosyl chloride (TsCl), leading to the selective functionalization at 75 °C of a secondary equatorial hydroxy function flanked by an axial one in a pyranoside. The procedure is endowed with several advantages, such as the use of cheap reagents, experimental simplicity, and the need for reduced reaction times in comparison with other known approaches.

Acid-Mediated Sulfonylthiolation of Arenes via Selective Activation of SS-Morpholino Dithiosulfonate.

A trifluoroacetic-acid-mediated desulfurilative sulfonylthiolation of arenes using SS-morpholino dithiosulfonate is described. This system is based on selective activation of the morpholino group over the tosyl group of the doubly transformable sulfur surrogate. Mechanistic studies suggested that the reaction proceeds through electrophilic aromatic substitution followed by sulfur extrusion. The wide substrate scope of this reaction and the transformability of the resulting thiosulfonates enable expeditious access to divergent multifunctionalized sulfides.

A TD-DFT molecular screening for fluorescence probe based on excited-state intramolecular proton transfer of 2’-hydroxychalcone derivatives

A systematic screening of fluorescence probe based on excited-state intramolecular proton transfer (ESIPT) of 2’-hydroxychalcone (2HC) derivatives with different electron donating (EDG) and electron withdrawing (EWG) groups at para position of phenol moiety (R1) and para position of the connected benzene ring to carbonyl (R2) of 2HC has been carried out by the best method of choice at ωB97XD/6-311++G(d,p) level. Seven selected 2HC derivatives with OH donor having mono-substitution with –NMe2 at R1 position or di-substitution with –NMe2 at R1 position and EDG (Me, OMe, NMe2) or EWG (Br, Cl, F) at R2 position have passed all required parameters (photophysical parameters, kinetic and thermodynamic parameters). Whereas, seven selected 2HC derivatives with NH donor having the same substituents as the 2HC derivatives with OH donor have passed photophysical parameters but failed kinetic and thermodynamic parameters due to high PT barrier and endothermic reaction. To ensure the effective ESIPT occurrence, a hydrogen atom on the amine group of NH donor derivatives is replaced with a tosyl (Ts) group, providing the Ts-substituted NH donor derivatives. The Ts substituent helps strengthening the intramolecular hydrogen bond, leading to low PT barrier with exothermic reaction thus facilitating ESIPT process. The systematically screening procedure from this theoretical calculation is beneficial for the design of fluorescent molecular probes utilizing the ESIPT process.

Base-mediated sequential one-pot approach for the synthesis of 2,3-disubstituted indoles from 2-(tosylamino)aryl-substituted para-quinone methides

a bstract A one-pot approach has been developed for the synthesis of 2,3-disubstituted indoles through a base-mediated N-alkylation of 2-(tosylamino)aryl-substitued para-quinone methides with halomethylaryl ketones followed by intramolecular cyclization and tosyl group elimination sequence. This one-pot protocol provides direct access to a wide range of 2,3-disubstituted indoles in moderate to good yields under mild conditions.

Regiospecific substitution of the β-vinylic sp2 carbon of cyclohexenones bearing the α-chloro- and β-tosylate-groups: Single crystal XRD/Hirshfeld surface/in-silico studies of three representative compounds

2-Chloro-3-tosyl-5,5-dimethyl-2-cyclohexenone was subjected to a series of regiospecific Suzuki-Miyaura cross-coupling reactions in suspensions of nine different substituted boronic acids, Pd(OAc)2, P(Ph3)3, K3PO4 and 1,4-dioxane solvent, under sealed tube conditions. The regiospecific substitution of the tosyl-group by the aryl group in preference over the chloride- group was observed. A comparison between the bromo- and tosylate group’s reactivities is highlighted. Using the methodology, the products: 2-chloro-3-aryl-5,5-dimethyl-2-cyclohexenones were isolated in greater than 85% yields. Good quality crystals of three representative compounds were obtained by slow evaporation technique and subjected to single crystal XRD studies, Hirshfeld surface analysis, 3-D energy framework, and molecular docking studies. Crystal data for compound 3; C15H17ClO4S: monoclinic, space group P21/c (no. 14), a = 8.8687(3) Å, b = 10.5537(4) Å, c = 16.6862(7) Å, β = 89.807(3)°, V = 1561.78(10) Å3, Z = 4, T = 290 K, μ(MoKα) = 0.390 mm-1, Dcalc = 1.398 g/cm3, 13623 reflections measured (6.716° ≤ 2Θ ≤ 54.962°), 3570 unique (Rint = 0.0467, Rsigma = 0.0512) which were used in all calculations. The final R1 was 0.0452 (I > 2σ(I)) and wR2 was 0.1019 (all data). Crystal data for compound 5e; C20H18O2FCl: monoclinic, space group P21/c (no. 14), a = 6.4900(5) Å, b = 18.6070(13) Å, c = 14.2146(11) Å, β = 102.324(2)°, V = 1677.0(2) Å3, Z = 4, T = 296(2) K, μ(MoKα) = 0.239 mm-1, Dcalc = 1.309 g/cm3, 25575 reflections measured (6.262° ≤ 2Θ ≤ 52.224°), 3283 unique (Rint = 0.0494, Rsigma = 0.0307) which were used in all calculations. The final R1 was 0.0875 (I > 2σ(I)) and wR2 was 0.2056 (all data). Crystal data for compound 5h; C12H13OSCl: triclinic, space group P-1 (no. 2), a = 6.7517(6) Å, b = 8.8376(9) Å, c = 12.6049(12) Å, α = 109.538(3)°, β = 98.597(3)°, γ = 90.417(3)°, V = 699.52(12) Å3, Z = 2, T = 290 K, μ(MoKα) = 0.410 mm-1, Dcalc = 1.376 g/cm3, 28754 reflections measured (6.114° ≤ 2Θ ≤ 59.288°), 3898 unique (Rint = 0.0544, Rsigma = 0.0349) which were used in all calculations. The final R1 was 0.1101 (I > 2σ(I)) and wR2 was 0.2481 (all data).

Amphiphilic molecular brushes with regular polydimethylsiloxane backbone and poly-2-isopropyl-2-oxazoline side chains. 1. Synthesis, characterization and conformation in solution

The samples of molecular brushes with a polydimethylsiloxane backbone and side chains of poly-2-isopropyl-2-oxazoline have been synthesized. Regular polydimethylsiloxane with undecene tosylate groups in every fourth siloxane unit was used as a macroinitiator. Two prepared samples are characterized by the same grafting density of side chains, but their different length and copolymer molar mass, 400,000 and 710000 g⋅mol−1. Solution behavior study revealed that macroinitiator and its precursor are flexible-chain polymers and macroinitiator’s thermodynamic rigidity is similar to one of polydimethylsiloxane. It was shown that the conformation of the graft copolymer molecules in a selective solvent resembles a polymer star because of the backbone of molecular brushes is strongly folded and shielded from the solvent by the side chains. The thermoresponsiveness of the synthesized molecular brushes in aqueous solutions has been demonstrated.

Improved Oxidative C-C Bond Formation Reactivity of High-Valent Pd Complexes Supported by a Pseudo-Tridentate Ligand.

There is a large interest in developing oxidative transformations catalyzed by palladium complexes that employ environmentally friendly and economical oxidizing reagents such as dioxygen. Recently, we have reported the isolation and characterization of various mononuclear PdIII and PdIV complexes supported by the tetradentate ligands N,N'-dialkyl-2,11-diaza[3.3](2,6)pyridinophane (RN4, R = tBu, iPr, Me), and the aerobically induced C-C and C-heteroatom bond formation reactivity was investigated in detail. Given that the steric and electronic properties of the multidentate ligands were shown to tune the stability and reactivity of the corresponding high-valent Pd complexes, herein we report the use of an asymmetric N4 ligand, N-mehtyl-N'-tosyl-2,11-diaza[3.3](2,6)pyridinophane (TsMeN4), in which one amine N atom contains a tosyl group. The N-Ts donor atom exhibits a markedly reduced donating ability, which led to the formation of transiently stable PdIII and PdIV complexes, and consequently the corresponding O2 oxidation reactivity and the subsequent C-C bond formation were improved significantly.

Tosylation Optimization, Characterization and Pyrolysis Kinetics of Cellulose Tosylate

AbstractCellulose tosylates with different degree of substitution (DS) were prepared by reacting cellulose in DMAc/LiCl with p‐tosyl chloride at 8 °C in the presence of triethylamine. The effects of number of mole of tosyl chloride (A), number of mole of base (triethylamine) (B) and reaction time (C) on DS were studied by Response Surface Methodology (RSM) known as Box‐Behnken Design (BBD). It was found that A is the main factor influencing DS and the interaction between B and C is negligible. An optimal DS value of 2.79 was obtained with A=6.96 and B=2.99 mol eq. at a reaction time C=24 h. The synthetic polymers were characterized by elemental analyses, FT‐IR, NMR and SEM spectroscopy. The results indicated that the cellulose was successfully tosylated with various DS. Cellulose tosylate with DS=0.5 and DS=2 were subjected to thermo‐gravimetric analysis under inert atmosphere. The kinetic parameters were determined by Coats‐Redfern method. Thermal analyses and kinetics indicates that the lower DS of tosyl group the higher thermal stability is. Thus, cellulose lose its stability after esterification with p‐tosyl chloride.

Model Substrate/Inactivation Reactions for MoaA and Ribonucleotide Reductases: Loss of Bromo, Chloro, or Tosylate Groups from C2 of 1,5-Dideoxyhomoribofuranoses upon Generation of an α-Oxy Radical at C3.

We report studies on radical-initiated fragmentations of model 1,5-dideoxyhomoribofuranose derivatives with bromo, chloro, and tosyloxy substituents on C2. The effects of stereochemical inversion at C2 were probed with the corresponding arabino epimers. In all cases, the elimination of bromide, chloride, and tosylate anions occurred when the 3-hydroxyl group was unprotected. The isolation of deuterium-labeled furanone products established heterolytic cleavage followed by the transfer of deuterium from labeled tributylstannane. In contrast, 3-O-methyl derivatives underwent the elimination of bromine or chlorine radicals to give the 2,3-alkene with no incorporation of label in the methyl vinyl ether. More drastic fragmentation occurred with both of the 3-O-methyl-2-tosyloxy epimers to give an aromatized furan derivative with no deuterium label. Contrasting results observed with the present anhydroalditol models relative to our prior studies with analogously substituted nucleoside models have demonstrated that insights from biomimetic chemical reactions can provide illumination of mechanistic pathways employed by ribonucleotide reductases (RNRs) and the MoaA enzyme involved in the biosynthesis of molybdopterin.

Electrochemical Reduction of α‐Amino Allenylphosphonates to α‐Amino Allylphosphonates

α‐Amino allenylphosphonates are reduced to α‐amino allylphosphonates using electrochemical processes. The reduction products are obtained in moderate to good yields. Moreover, in the case of tosylamine compounds, we were pleased to take advantage of a simultaneous reduction and cleavage of the tosyl group from the nitrogen atom to access unprotected amino‐allylphosphonates. The mechanism of this reduction is also discussed.

Photoactivated semi-synthetic derivative of osajin selectively interacts with G-quadruplex DNA

Natural and synthetic small molecules targeting G-quadruplex are currently being studied. These peculiar DNA arrangements arise in guanine-rich sequences located in telomeres, oncogene promoters and in several viruses. Two semi-synthetic derivatives of osajin, a natural isoflavone from Maclura pomifera, were prepared and screened for their binding affinity towards G-quadruplex and double stranded DNA (dsDNA) using electrospray mass spectrometry (ESI-MS). Although an overall decrease in affinity for DNA was observed, one of the derivatives showed improved selectivity for G-quadruplex over dsDNA, retaining structure stabilization properties. Binding motif was studied by collision-induced dissociation (CID) assays and molecular docking, that suggested stacking as the preferential interaction pattern. Moreover, the compound selectively induced DNA damage on the G-quadruplex sequence upon UV irradiation, due to the presence of the photoreactive aryl tosylate group.

Aminated cellulose as a versatile adsorbent for batch removal of As(V) and Cu(II) from mono- and multicomponent aqueous solutions

A bioadsorbent (CEDA) capable of adsorbing As(V) and Cu(II) simultaneously was prepared by tosylation of microcrystalline cellulose (MC) and nucleophilic substitution of the tosyl group by ethylenediamine. MC, tosyl cellulose, and CEDA were characterized by elemental C, H, N, and S analysis, infrared spectroscopy, and 13C solid-state nuclear magnetic resonance spectroscopy. The adsorption of As(V) and Cu(II) on CEDA was evaluated as a function of solution pH, contact time, and initial solute concentration. The maximum adsorption capacities of CEDA for As(V) and Cu(II) were 1.62 and 1.09 mmol g−1, respectively. The interactions of As(V) and Cu(II) with CEDA were elucidated using thermodynamic parameters, molecular quantum mechanics calculations, and experiments with ion exchange of Cd(II) by Cu(II), and As(V) by SO42−. Adsorption enthalpies were determined as a function of surface coverage of the CEDA, using isothermal titration calorimetry, with ΔadsH° values of −32.24 ± 0.07 and −93 ± 2 kJ mol−1 obtained for As(V) and Cu(II), respectively. The potential to reuse CEDA was evaluated and the interference of other ions in the adsorption of As(V) and Cu(II) was investigated. Multi-component experiments showed that Cd(II), Co(II), Ni(II), and Pb(II) did not interfere in the adsorption of Cu(II), while SO42− inhibited As(V) adsorption.

Regioselective Ring Expansion of 3-Ylideneoxindoles with Tosyldiazomethane (TsDAM): A Metal-Free and Greener Approach for the Synthesis of Pyrazolo-[1,5-c]quinazolines.

An efficient, metal-free approach to access pyrazolo-[1,5-c]quinazolines with 3-ylideneoxindoles and tosyldiazomethane (TsDAM) under mild aqueous reaction conditions has been developed and the solvent involvement in the present reaction has also been explored for the first time. This greener approach involves 1,3-dipolar cycloaddition, regioselective ring expansion, followed by the elimination of tosyl group with aqueous base in a single operation, and the product can be isolated in high purity without column chromatographic separation. The method is also compatible with a large variety of functional groups, providing good to excellent yields in water, thus resulting in a decrease of environmental impact in the pharmaceutical industry.

Synthesis and Antitumor Activity of 3-Amino-3,4-Seco-Lupa-4(23),20(29)-Diene Derivatives

3-Amino-3,4-seco-lupa-4(23),20(29)-diene and its 3,28-bis (cyanoethyl) and 3-aminopropyl derivatives caused growth inhibition or death of nine human cancer cell lines. Leukemia, melanoma, and non-small-cell lung, colon, CNS, and kidney cancer cell lines were most sensitive to these compounds. Antitumor activity decreased with a tosyl group in the C-28 position or acetates on C-3 and C28.

From Isocyanides to Iminonitriles via Silver-mediated Sequential Insertion of C(sp3)-H Bond.

SummaryHeterocycles are prevalent constituents of many marketing drugs and biologically active molecules to meet modern medical challenges. Isocyanide insertion into C(sp3)–H bonds is challenging especially for the construction of quaternary carbon centers. Herein, we describe an efficient strategy for the synthesis of α-iminonitrile substituted isochromans and tetrahydroisoquinolines (THIQs) with quaternary carbon centers through silver-triflate-mediated sequential isocyanide insertion of C(sp3)–H bonds, where isocyanide acts as the crucial “CN” and “imine” sources. The produced α-iminonitriles have extensive applications as valuable synthetic building blocks for pharmacologically interesting heterocycles. This protocol could be further applied for the synthesis of iminonitrile-decorated phenanthridines and azapyrene. Interestingly, a remarkable aggregation-induced emission (AIE) effect was first observed for an iminonitrile-decorated pyrene derivative, which may open a particular area for iminonitrile applications in materials science.

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen, heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.

Modulating N H-based excited-state intramolecular proton transfer by different electron-donating/withdrawing substituents in 2-(2′-aminophenyl)benzothiazole compounds

Abstract The N H-based excited-state intramolecular proton transfer process of 2-(2′-aminophenyl)benzothiazole (PBT-NH2) and its three derivatives have been explored by the time-dependent density functional theory (TD-DFT) method. The scanned potential energy curves reveal that the energy barriers of the first singlet excited state of the four compounds along the ESIPT reactions are predicted at 8.74, 8.98, 6.72 and 1.69 kcal/mol respectively, suggesting that the inclusion of a strong electron-withdrawing tosyl (Ts) group can remarkably facilitate the occurrence of the ESIPT reaction, while the involvement of an electron-donating methyl group has slight opposite effect on the ESIPT process of the amino-type hydrogen-bonding system.