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The influence exerted by the kind of the tin precursor [SnCl4·5H2O or H2Sn(OH)6] and by the Cl– content (0.86–0.97 wt %) on the adsorption and catalytic properties of Pt sites in Pt/Sn–Al2O3–Cl heptane reforming catalysts was studied. The kind of the Sn precursor does not significantly influence the dispersity of the Pt particles. Among Pt sites, electron-deficient Pt forms prevail in the presence of Sn and at increased Cl– content. The acidity of the surface of the Pt/Al2O3–Cl catalyst increases on introducing Sn and with an increase in the Cl– content owing to strong acid sites. The catalyst containing 0.2 wt % Sn from H2Sn(OH)6 and 0.86 wt % Cl– exhibits the highest selectivity of the heptane aromatization and slightly increased selectivity of the С1–4 gas formation. [ABSTRACT FROM AUTHOR]

A synthesis of a series of novel fused tricyclic heterocyclic compounds has been achieved in one-pot reaction set up starting from (E)-3-(2-oxo-2-phenylethylidene)indolin-2-one and 1,4-benzoxazinone/quinoxalinone derivatives promoted by tin(IV) chloride. The reaction is supposed to occur via a sequential intermolecular Michael addition of the 1,4-benzoxazinone derivatives to the oxindoles, intramolecular cyclization, and aromatization with the elimination of water. Apart from spectroscopic characterization, the structure of one of the pyrrolo[1,4]benzoxazinone derivative is confirmed by single-crystal X-ray diffraction. Thus, the developed domino protocol provides easy access to multifunctional pyrrolo[1,4]benzoxazines in one-pot with high efficiency. [ABSTRACT FROM AUTHOR]

A series of novel 1-(4-amino-6-methyl-1-aryl-1H-pyrazolo[3,4-b]pyridin-5-yl)- ethanones and 6-methyl-1-aryl-1H-pyrazolo[3,4-b]pyridin-4-amines were prepared by the annulation of 5-amino-1-aryl-1H-pyrazole-4-carbonitriles with acetylacetone in the presence of tin(IV) chloride. The results demonstrated that the ethanones are the precursors of second compounds. [ABSTRACT FROM AUTHOR]

The [3+2] cycloaddition reaction of mesityl propargyl sulfide with ethyl glyoxylate was found to occur by using tin(IV) chloride to give a 2,5-dihydrofuran derivative. On the other hand, when 3-silyl propargyl sulfides were used, allyl alcohols were obtained. In the case of propargyl sulfides possessing dimethyl groups at the α-position of the propargyl group, cycloaddition products were obtained even if a silyl group was present on the propargyl group. In addition, mesityl propargyl selenides also reacted with ethyl glyoxylate by using tin(IV) chloride to give the corresponding [3+2] cycloaddition products. [ABSTRACT FROM PUBLISHER]

The reaction of SnCl4with β-chlorovinyl aldehydes in anhydrous dichloromethane gave a series of octahedral complexes of the general formula SnCl4·2L (L = aldehyde). The adducts have been characterized in solution using multinuclear (1H,13C, and119Sn) NMR and IR spectroscopy. Solution NMR studies show that the complexes undergo rapid ligand dissociation at ambient temperature. Ligand exchange is slowed significantly at low temperature, such that, in most of the complexes, it is possible to identify both thecisandtransisomers with predominance of thecisform. The magnitude of the metal-ligand interaction was estimated on the basis of119Sn NMR chemical shifts and used to classify the aldehydes studied according to their Lewis basicity. [ABSTRACT FROM PUBLISHER]

Four octahedral complexes of the type SnCl4.2L [L = (R2N)3P(E): E = Se; R = Me(1), Et(2) and E = S; R = Me(3), Et(4)] have been studied in solution by multinuclear (31P, 77Se, and 119Sn) NMR spectroscopy. 31P and 77Se NMR data were informative of changes associated with complex formation. The solution structure of the complexes was confirmed by their 119Sn NMR spectra that showed two triplet features for each complex, attributed to a mixture of the expected cis and trans isomers. The triplet signal is due to the coupling with two equivalent phosphorus atoms, consistent with an octahedral geometry around the tin center. In addition, density functional theory (DFT)/B3LYP calculations have been carried out to support the interpretations of NMR data. The results are discussed and compared with those reported for related complexes. GRAPHICAL ABSTRACT [image omitted] [ABSTRACT FROM AUTHOR]

Abstract: The surfactant sodium bis(2-ethylhexyl) sulfosuccinate based tin(IV) phosphate (AOT-SnP) fibrous ion exchanger has been synthesized and characterized by using different physico-chemical methods. The characterization of the exchanger was performed by using infrared (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental analysis. The ion exchange property was studied by determining the ion exchange capacity, elution and concentration behavior of the cation exchanger. The thermal behavior of exchanger was studied by performing ion exchange capacity at different temperatures. Adsorption studies on the synthesized material showed that it is highly selective for Cd2+, Zn2+and Hg2+ ions. Therefore, the separation of Cd2+, Zn2+and Hg2+ ions from the synthetic waste water has been performed on its column and observed to be quite effective in presence of acid, alkali, alkaline earth and other transition metals. [Copyright &y& Elsevier]

Abstract: A racemic synthesis of the ABCD ring core of the ambiguines that preserves the tertiary alcohol has been accomplished in a convergent synthesis in 10 synthetic steps, in an overall yield of 46% from commercially available 4-bromoindole and m-methylanisole. [Copyright &y& Elsevier]

A facile synthesis of potential acetylcholinesterase (AChE) inhibitors, the tacrine analogues 3a-p, has been accomplished by direct cyclocondensation of 1-aryl-4-cyano-5-aminopyrazole with β-ketoesters using tin(IV) chloride as catalyst. The structures of all the compounds have been confirmed by IR, 1H- and 13C-NMR. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of meso-tetraarylporphyrins (H2T(X)PP) with SnCl4 affords green intermediate sitting-atop (i-SAT) complexes, [(H2T(X)PP)SnCl4]. UV–Vis, 1H NMR and 13C NMR spectral data show that the porphyrin core of the complexes is distorted, thus two nitrogen atoms of the pyrrolenine groups on one side of the porphyrin plane act as electron donors to the tin center of SnCl4. The intermediate sitting-atop (i-SAT) complex is formed each time during the incorporation of the metal center, where in the intermediate state the pyrrolic protons still remain on the porphyrin. [Copyright &y& Elsevier]

Abstract: The two octahedral complexes SnCl4 ·2(O)P(NR2)2OCH2CF3 (R=Me (1) or Et (2)) have been prepared from SnCl4 and the ligands (R2N)2P(O)OCH2CF3 in chloroform solution. Both adducts have been characterised by (31P and 119Sn) NMR, IR spectroscopy and elemental analysis. The NMR data show that the complexes exist as mixtures of cis and trans isomers in solution with the latter isomer being the predominant species. The structure of 1 has been determined by X-ray crystallography. Accordingly, the structure is centrosymmetric and the two ligands are bound trans to each other in the octahedral tin complex. DFT/B3LYP calculations show that trans configuration does indeed lead to the lowest energy species. Comparison of the structural, NMR and theoretical data of both complexes with those related to SnCl4 ·2L (L=(Me2N)3P(O) and (Me2N)2P(O)F) further supports the important effects of the nature of the substituents in the ligand on the stereochemistry of the complex formed. [Copyright &y& Elsevier]

The arabinogalactan is a crucial constituent of the cell wall of mycobacteria. Both monosaccharides (arabinose and galactose) are found in the furanose configuration, absent in mammals. An efficient synthesis of α-D-Araf-(1→5)-D-Galf, the linker unit of the arabinan to the galactan, is described. The strategy relies on the use of a conveniently substituted D-galactono-1,4-lactone as a precursor of the reducing furanose ring. The glycosylation step was performed by the tin(IV) chloride promoted method using 1,2,3,5-tetra-O-benzoyl-α,β-D-arabinofuranose. The arabinose donor was obtained in a crystalline state in one step by benzoylation of arabinose in hot pyridine. Selective glycosylation of the exocyclic OH-5 was obtained in 75% yield to give 2,3,5-tri-O-benzoyl-α-D-arabinofuranosyl-(1→5)-2,6-di-O-pivaloyl-D-galactono-1,4-lactone. Reduction with disiamylborane gave the disaccharide synthon, useful for further glycosylations. Dec-9-enyl α-D-Araf-(1→5)-β-D-Galf, a convenient substrate for arabinofuranosyl transferases studies, was obtained by the trichloroacetimidate method of glycosylation. [ABSTRACT FROM AUTHOR]

The compounds [SnCl4(L)n] (where L is pyridine (py), 4-methylpyridine (γ-pico), 3-methylpyridine (β-pico), piperidine (pipd), morpholine (morph), piperazine (pipz), 3-cyanopyridine (3-cyanopy), 4-cyanopyridine (4-cyanopy), quinoline (quin) or 2,2′-bipyridine (bipy) and n=2, 1 or 3/2) were synthesized and characterized by elemental analysis, melting points, thermal studies and IR spectroscopy. The enthalpies of dissolution of adducts, tin(IV) chloride and ligands in 1,2-dichloroethane or 25% (v/v) aqueous HCl 1.2 M in methanol were measured and, by using thermochemical cycles, the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reaction (ΔrH°), the standard enthalpies of formation (ΔfH°), the standard enthalpies of decomposition (ΔDH°), the lattice standard enthalpies (ΔMH°) and the standard enthalpies for the Lewis acid/base reaction in the gaseous phase (ΔrH°). The mean standard enthalpies of the tin–nitrogen bonds (D¯(Sn–N)) have been estimated. Based on these last values, the basicity orders: pipd>morph>γ-pico=β-pico>py>4-cyanopy>3-cyanopy and pipz>quin are obtained. [Copyright &y& Elsevier]

Tin(IV) chloride selectively promotes the nucleophilic attack of methyl acetoacetate to the cyano instead of the olefinic carbon atom of α,β-unsaturated nitriles to give enaminoketoesters. In the presence of an excess of ketoester a second C–C bond formation occurs followed by cyclisation affording substituted pyridines in a selective cascade sequence. [Copyright &y& Elsevier]

• Chiral acetamide oxazolidinones produced. • Reactions with indoles gave pyrroloindoline products. • This structure is found in many natural products. • Numerous indoles gave up to 91% yield with high selectivity. Chiral N- 2-acetamidoacrylyl oxazolidinones were produced and reacted with indoles under Lewis acid conditions to generate hexahydropyrrolo[2,3- b indole products in a formal [3 + 2] cycloaddition process. Optimal conditions included the use of tin(IV) chloride in methylene chloride at 0 °C. Pyrroloindoline products were obtained from various indoles with shorter reaction times (12 hr) up to 91% yield with high, >20:1 exo selectivity. A mechanism involving reversible conjugate addition followed by an enamine lone-pair-iminium capture, tautomerization, and tin-enolate protonation accounts for the selectivity. The method enables selective applications to pyrroloindoline targets and further refinement with chiral catalysts. [ABSTRACT FROM AUTHOR]

2-Propenyl tin species, prepared from 3-halopropenes or 2-propenyl mesylate with tin(IV) chloride and tetrabutylammonium iodide in dichloromethane, causes nucleophilic addition to aldehydes to produce the corresponding homoallylic alcohols. [Copyright &y& Elsevier]

Allyl aryl ethers undergo facile Claisen rearrangement under mild conditions catalysed by tin(IV) chloride. [ABSTRACT FROM AUTHOR]