Presence Of SnCl4 Research Articles

Palladium nanoparticles supported on modified polystyrene resin as a polymeric catalyst for Sonogashira--Hagihara coupling reactions

Pd(0) nanoparticles supported on modified crosslinked polystyrene were synthesized and characterized. Crosslinked polystyrene was reacted with trioxane and chlorotrimethylsilane in the presence of SnCl$_{4}$ to form Merrifield resin. The Merrifield resin was then converted to polymer-bound $\beta $-aminoalcohol and subsequently to $\beta$-aminophosphinite ligand. This polymeric ligand was reacted with PdCl$_{2}$ to obtain a polymeric Pd(0) complex. The TEM image of the Pd catalyst showed good dispersion of catalytic sites. The Pd catalyst exhibits excellent activity and stability in copper-free Sonogashira-Hagihara cross-coupling reactions under aerobic conditions. This protocol can be applied efficiently to the coupling reactions of chloro- as well as iodo- and bromo-arenes. The catalyst can be reused several times without any considerable decrease in its activity.

Green Biginelli-type Reaction: Solvent-free Synthesis of 5-unsubstituted 3,4-dihydropyrimdin-2(1H)-ones

The Biginelli-type compounds, 5-unsubstituted 3,4-dihydropyrimdin-2(1H)-ones were synthesized by a one-pot three-component condensation of aromatic aldehydes, aromatic ketones and urea in the presence of SnCl4 · 5H2O under solvent-free conditions. The advantages of this method are short reaction time (4–10 min), excellent yields (74–97%), inexpensive catalyst and solvent-free conditions. A plausible mechanism was proposed.

An efficient method for synthesis of 3-arylbenzo[f]quinoline-1,2-dicarboxylates catalyzed by SnCl2

A wide variety of 3-arylbenzo[f]quinoline-1,2-dicarboxylates and their dehydro derivatives have been synthesized by one-pot, three-component reaction of an aromatic aldehyde, naphthalene-2-amine, and dimethyl but-2-ynedioate in the presence of SnCl2 under reflux in acetonitrile. This procedure has several advantages, for example high yield, short reaction time, easy work-up, little pollution, and low price of the catalyst.

Brain targeting by intranasal drug delivery (INDD): a combined effect of trans-neural and para-neuronal pathway

The effectiveness of intranasal drug delivery for brain targeting has emerged as a hope of remedy for various CNS disorders. The nose to brain absorption of therapeutic molecules claims two effective pathways, which include trans-neuronal for immediate action and para-neuronal for delayed action. To evaluate the contribution of both the pathways in absorption of therapeutic molecules and nanocarriers, lidocaine, a nerve-blocking agent, was used to impair the action potential of olfactory nerve. An anti-Parkinson drug ropinirole was covalently complexes with 99mTc in presence of SnCl2 using in-house developed reduction technology. The radiolabeled formulations were administered intranasally in lidocaine challenged rabbit and rat. The qualitative and quantitative outcomes of neural and non-neural pathways were estimated using gamma scintigraphy and UHPLC-MS/MS, respectively. The results showed a significant (p ≤ 0.005) increase in radioactivity counts and drug concentration in the brain of rabbit and rat compared to the animal groups challenged with lidocaine. This concludes the significant contribution (p ≤ 0.005) of trans-neuronal and para-neuronal pathway in nose to brain drug delivery. Therefore, results proved that it is an art of a formulator scientist to make the drug carriers to exploit the choice of absorption pathway for their instant and extent of action.

ChemInform Abstract: Rapid Access to Homoallylic Alcohols via Pd(OAc)2 Catalyzed Barbier Type Allylation in Presence of DMAP.

AbstractThe Pd‐catalyzed allylation of both aldehydes and ketones by using allyl bromide in the presence of SnCl2·2H2O as reducing agent is significantly promoted by catalytic amounts of DMAP.

ChemInform Abstract: Zinc‐Mediated Highly α‐Regioselective 1,4‐Addition of Chalcones with Prenyl Bromide in THF.

α-Regioselective addition to chalcones was realized by use of in situ generated prenylzinc reagents from zinc and prenyl bromide in the presence of SnCl4 in a 1,4-addition fashion. The approach uses the reagent combination of prenyl bromide, zinc, and SnCl4 in THF, all of which are inexpensive, readily available, and easily removable after the reaction.

3D graphene aerogel-supported SnO2 nanoparticles for efficient detection of NO2

Three-dimensional (3D) graphene aerogel-supported SnO2 (SGA) nanoparticles (NPs) are presented by a one-pot solvothermal treatment of graphene oxide in the presence of SnCl4 followed by freeze drying. The size of SnO2 nanoparticles on the graphene aerogel is as small as 5–10 nm with uniform distribution. The 3D SnO2–graphene aerogel exhibits interconnected macroporous networks which will be beneficial for gas detection. The SGA shows excellent response and selectivity towards NO2 when other common gases are present at room temperature (RT). The gas sensing responses of the resulting nanocomposites demonstrate that macroporosity in the SGA significantly improves the response and recovery time compared with the 2D SnO2–graphene nanocomposite. The sensing mechanism and the reasons for the better response are also discussed.

Effect of phenol formaldehyde resin as vulcanizing agent on flow behavior of HDPE/PB blend

Thermoplastic elastomer (TPE) based on High density polyethylene (HDPE)/polybutadiene (HDPE/PB=70/30 parts) blends containing 1, 3, 5, 7 and 10wt.% of dimethylol phenolic resin as a vulcanizing agent in the presence of SnCl2 as catalyst was prepared. The dimethylol phenolic resin was prepared in our laboratory. The blends were compounded in mixer-60 attached to a Haake rheochord meter-90. The rheological properties were measured at temperatures 140, 160, 180 and 200°C. The linearity of the flow curve appeared for 5% of the vulcanizing agent. The shear stress and shear viscosity have increased upon increasing the shear rate over a range of loading levels of vulcanizing agent of 1%, 3%, 5%, 7% and 10%. This may be attributed to the increased vulcanization between polyethylene and the rubber blend. The flow behavior index of the system shows a pseudo plastic nature behavior (since n<1). The consistency index (K) increased with the increase in the phenol formaldehyde resin content and the temperature. Hence, the increase in the value of the consistency index (K) of the polymer melts refers to more viscous materials prepared. The activation energy for the TPE blends fluctuated indicating that there is phase separation; where each polymer behaved separately. This study showed that HDPE/PB blends are characterized with good rheological properties, which can be recommended to be processed with the injection molding technique.

Novel method of synthesis of 5''-phosphate 2'-O-ribosyl-ribonucleosides and their 3'-phosphoramidites.

Synthesis of 5''-phosphate 2'-O-ribosylribonucleosides [Nr(p)] of four common ribonucleosides, and 3'-phosphoramidites of 5''-phosphate 2'-O-ribosyladenosine and 2'-O-ribosylguanosine using the H-phosphonate chemistry is described. An additional ring protected by benzoyl groups was incorporated into the main ribosyl ring in the reaction with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-ribofuranose in the presence of SnCl4. The obtained 2'-O-ribosylribonucleosides (Nr) were applied in the subsequent transformations with selective deprotection. Ethanolamine was applied as a very convenient reagent for selective removal of benzoyl groups. Additionally, the tetraisopropyldisiloxane-1,3-diyl (TIPDSi) group was found to be stable under these deprotection conditions. Thus, the selectively deprotected 5''-hydroxyl group of Nr was transformed into an H-phosphonate monoester which was found to be stable under the following conditions: the removal of the TIPDSi group with triethylammonium fluoride and the dimethoxytritylation of the 5''-hydroxyl function. The 5''-H-phosphonate of Nr precursors was easily transformed to the corresponding dicyanoethyl 5''-O-phosphotriesters before phosphitylation, which gave 3'-phosphoramidite units of Nr(p) in high yield. The derived phosphoramidite units were used in an automated oligonucleotide synthesizer to produce dimer Ar(p)T via the phosphoramidite approach. The obtained products were fully deprotected under standard deprotection conditions giving dimers with a 5''-phosphate monoester function. Application of an alkaline phosphatase to prove the presence of an additional phosphate group was described.

Zinc-Mediated Highly α-Regioselective 1,4-Addition of Chalcones with Prenyl Bromide in THF

α-Regioselective addition to chalcones was realized by use of in situ generated prenylzinc reagents from zinc and prenyl bromide in the presence of SnCl4 in a 1,4-addition fashion. The approach uses the reagent combination of prenyl bromide, zinc, and SnCl4 in THF, all of which are inexpensive, readily available, and easily removable after the reaction.

ChemInform Abstract: Synthesis of Isoindolo[2,1‐a]quinazoline‐5,11‐dione Derivatives via the Reductive One‐Pot Reaction of N‐Substituted 2‐Nitrobenzamides and 2‐Formylbenzoic Acids.

Various isoindolo[2,1-a]quinazoline-5,11-dione derivatives 3 were synthesized in good yields by means of the reductive reaction of N-substituted 2-nitrobenzamides 1 and 2-formylbenzoic acids 2 in the presence of SnCl2⋅2 H2O under reflux in EtOH (Scheme, Table). The procedure needed two steps, the reduction of the nitro group of the 2-nitrobenzamide and ring closure by nucleophilic addition of the NH2 group to both the formyl and carboxylic acid CO groups.

Microwave-Assisted Solid-Phase Synthesis of a 1,2-Disubstituted Benzimidazole Library by Using a Phosphonium Linker

An efficient and rapid microwave-assisted solid-phase method for the synthesis of 5-methyl-1,2-disubstituted benzimidazoles derivatives has been developed. The phosphonium linker, obtained by reaction between polymer-supported triphenylphosphine and 4-fluoro-3-nitrobenzyl iodide, underwent aromatic substitution with primary amines, followed by one-pot reaction with aldehydes in the presence of SnCl2·2H2O, yielded the benzimidazole system under microwave irradiation. The final products were released from the resin with NaOH under microwave irradiation and were obtained in high purity and good overall yield.

Synthesis of Isoindolo[2,1‐a]quinazoline‐5,11‐dione Derivatives via the Reductive One‐Pot Reaction of N‐Substituted 2‐Nitrobenzamides and 2‐Formylbenzoic Acids

AbstractVarious isoindolo[2,1‐a]quinazoline‐5,11‐dione derivatives 3 were synthesized in good yields by means of the reductive reaction of N‐substituted 2‐nitrobenzamides 1 and 2‐formylbenzoic acids 2 in the presence of SnCl2⋅2 H2O under reflux in EtOH (Scheme, Table). The procedure needed two steps, the reduction of the nitro group of the 2‐nitrobenzamide and ring closure by nucleophilic addition of the NH2 group to both the formyl and carboxylic acid CO groups.

On the Synthesis and Coordination Properties of N‐Aryl‐substituted 1, 3, 2‐Diazaphospholidine‐4, 5‐diimines

AbstractNew 1, 3, 2‐diazaphospholidine‐4, 5‐diimines were synthesized by condensation of lithiated oxalamidines with PCl3 or PhPCl2, and characterized by spectral and analytic data. The products react selectively with [(nbd)W(CO)4], [Mo(CO)6], or [(PhCN)2PdCl2] to give stable complexes, in which the heterocycle binds as chelating, bidentate ligand through the nitrogen atoms of the diimine unit. Formation of P‐bound or dinuclear complexes was not observed. Reaction with PCl3 or AsCl3 in the presence of SnCl2 as reducing agent was unspecific. Evidence for the formation of bicyclic products arising from formal [4+1] cycloaddition between the diimine unit and a transient pnictogen(I) species was not obtained, and only a diimine complex of SnCl4 was isolated in moderate yield. Single‐crystal X‐ray diffraction studies reveal that coordination of the diimine unit induces a substantial structural distortion of the ligand framework, which allows to explain the occurrence of substantial 31P coordination shifts despite the absence of a direct metal‐phosphorus bond.

Tin-catalyzed efficient conversion of carbohydrates for the production of 5-hydroxymethylfurfural in the presence of quaternary ammonium salts

An efficient and tin-catalyzed production of 5-hydroxymethyl furfural (5-HMF) from carbohydrates is reported. The efficient conversion of glucose has been investigated using the combination of SnCl4 and different quaternary ammonium salts. It was found that tetrabutyl ammonium bromide (TBAB) was able to efficiently promote conversion of glucose to 5-HMF in the presence of SnCl4. For instance, a 69.1% yield of 5-HMF was obtained with SnCl4–tetrabutyl ammonium bromide (SnCl4–TBAB) system in DMSO for 2h at 100°C in air. The effects of catalyst amount, reaction time, and reaction temperature were investigated in detail. Furthermore, the SnCl4–TBAB was also employed to the conversion of fructose, sucrose, inulin, starch, and cellulose. The competitive results were obtained under mild conditions.

Dinuclear Olefin and Alkyne Complexes of Platinum(II)

AbstractBis(olefin) complexes of Zeise's dimer type – [{PtCl2(cis‐MeHC=CHMe)}2] (2) or [{PtCl2(c‐Hex)}2] (3, c‐Hex = cyclohexene) – were prepared by treatment of K2[PtCl4] in the presence of SnCl2 or K[PtCl3(cis‐MeHC=CHMe)] with the corresponding olefin. Zeise's dimer, [{PtCl2(H2C=CH2)}2] (1), was found to react in chloroform or dichloromethane with the internal alkynes RC≡CtBu (R = Me, tBu), provided that the cleaved‐off ethene was removed, to yield bis(alkyne) complexes of Zeise's dimer type [{PtCl2(RC≡CtBu)}2] (R = Me, 11; tBu, 12). Without removal of the ethene, mononuclear mixed ethene/alkyne complexes cis‐[PtCl2(H2C=CH2)(RC≡CtBu)] (R = Me, 8; tBu, 9) and cis‐[PtCl2(H2C=CH2)2] (10) were formed. Analogous reactions with alkynes RC≡CR′ bearing sterically less demanding substituents (R, R′ = Me, Et, nPr, Ph) led to (cyclobutadiene)platinum(II) complexes [PtCl2(C4R2R′2)] (R/R′ = Me/Me 4; Et/Et 5; Me/nPr 6) and [PtCl2(C4Me2Ph2)] (7). Furthermore, use of acetone (instead of CHCl3/CH2Cl2) as solvent in the reactions between 1 and sterically undemanding substituted alkynes resulted in bridge cleavage of Zeise's dimer (1) and in aldol addition and condensation reactions, thereby confirming why Chatt et al. in his analogous classical experiments (1961) observed only decomposition. Complexes 2–7 and 11/12 were isolated in pure states and fully characterized by elemental analysis, NMR spectroscopy, and X‐ray diffraction measurements (2, 11, 12). For the dinuclear bis(olefin) (1–3) and bis(alkyne) complexes (11, 12) solvent‐dependent equilibria between the transoid and cisoid isomers were observed, and these could even be ascertained crystallographically for complex [{PtCl2(tBuC≡CtBu)}2] (12), which crystallized both as the transoid isomer 12a and as the cisoid isomer 12b·CHCl3. Furthermore, consistent with DFT calculations, NMR measurements provided evidence of fast rotation and of hindered rotation of olefin and alkyne ligands, respectively, resulting in conformational isomers in 8 and 11.

Hydrogen peroxide route to Sn-doped titania photocatalysts

BackgroundThe work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurementsResultsThe presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solutionConclusionsDoping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders.

Facile synthesis of furoquinoline and effects on radical-induced oxidation of DNA

The aim of this work was to clarify the influences of the position of hydroxyl group and furo[2,3-b] moiety on the antioxidant effectiveness of quinoline. Thus, 4-methyl-2,3-dihydrofuro[2,3-b]quinolin-6-ol (PFQ), 4-methyl-2,3-dihydrofuro[2,3-b]quinolin-8-ol (OFQ), and 4-methyl-2,3-dihydrofuro[2,3-b]quinolin-7-ol (MFQ) were synthesized by a recyclization reaction of 1-acetyl-N-phenylcyclopropanecarboxamide in the presence of SnCl4 as the catalyst. The antioxidant capacities of PFQ, OFQ, and MFQ were evaluated in the experimental system of the oxidation of DNA caused by Cu2+/glutathione (GSH), •OH, and 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH). OFQ and PFQ were able to protect DNA against Cu2+/GSH- and •OH-induced oxidation because the furo[2,3-b] moiety was beneficial for stabilizing the produced furoquinoline radical. Moreover, MFQ can decrease the oxidation rate of AAPH-induced oxidation of DNA, while PFQ and OFQ can inhibit AAPH-induced oxidation of DNA for a period. The data obtained from AAPH-induced oxidation of DNA were treated by chemical kinetic method; it was found that PFQ and OFQ can trap 1.3 and 1.5 radicals, respectively. Therefore, the hydroxyl group at different positions changed the mechanism of furoquinoline in protecting DNA against radical-induced oxidation. Effects on Cu2+/glutathione-, •OH-, and peroxyl radical-induced oxidation of DNA.

New modulated design and synthesis of chiral CuII/SnIV bimetallic potential anticancer drug entity: In vitro DNA binding and pBR322 DNA cleavage activity

A new chiral ligand scaffold L derived from (R)-2-amino-2-phenyl ethanol and diethyl oxalate was isolated and thoroughly characterized by various spectroscopic methods. The ligand L was allowed to react with CuCl2·2H2O and NiCl2·6H2O to achieve monometallic complexes 1 and 2, respectively. Subsequently modulation of 1 and 2 was carried out in the presence of SnCl4·5H2O to obtain heterobimetallic potential drug candidates 3 and 4 possessing (CuII/SnIV and NiII/SnIV) metallic cores, respectively and characterized by elemental analysis and spectroscopic data including 1H, 13C and 119Sn NMR in case of 3 and 4. In vitro DNA binding studies revealed that complex 3 avidly binds to DNA as quantified by Kb and Ksv values. Complex 3 exhibits a remarkable DNA cleavage activity (concentration dependent) with pBR322 DNA and the cleavage activity of 3 was significantly enhanced in the presence of activators and follows the order H2O2>Asc>MPA>GSH. Complex 3 cleave pBR322 DNA via hydrolytic pathway and accessible to major groove of DNA.

Bowl‐shaped carbocations: easy to produce, hard to reduce

Stable nonplanar polyaromatic carbocation, [C20H10CH2Cl]+ (1) having the chloromethyl group covalently bound to the hub site of corannulene was prepared by reaction of C20H10 with CH2Cl2 and GaCl3 in the presence of SnCl2. The X‐ray diffraction study of the resulting salt, [1]∙[(SnCl)(GaCl4)2], revealed the presence of two rotational isomers for 1 in the crystal lattice. In the solid state, a complex polymeric inorganic anion of the overall composition [(Sn2Cl2)∙(GaCl4)4]∞ is formed with the cationic π‐bowls being attached to its backbone. Both X‐ray and nuclear magnetic resonance spectroscopic data of 1 indicate the sp3 hybridization of the C‐atom of corannulene at the attachment point. An electrochemical investigation of 1 and the series of related corannulene cations, [C20H10R]+ (R = CHxCl3–x (x = 0–3) and CH2CH2Cl), was carried out to elucidate the electronic consequences triggered by the above changes. This study revealed that the surface decoration of corannulene core makes the reduction of the resulting [C20H10R]+ species significantly more difficult (by about 0.3 V) with respect to the parent bowl. To evaluate the consequences of the observed one‐electron reduction and conceivable but not seen second‐electron reduction on the corannulene core, theoretical calculations at the density functional theory level have been carried out. Copyright © 2012 John Wiley &amp; Sons, Ltd.