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Different tributyltin phenoxides react at room temperature with ethyl propiolate in benzene, in the presence of tin(IV) chloride, triethylamine and their mixture to give the derivatives of 3-phenoxyacrylic acid ethyl ester. Exceptionally, 3-(2-hydroxyphenyl)acrylic acid ethyl ester and 3-(2-hydroxy-5-methylphenyl)acrylic acid ethyl ester have been obtained from the reaction of tributylphenoxytin and tributyl(p-tolyloxy)tin, respectively catalysed by SnCl4, and they have been easily hydrolysed to coumarin and 6-methylcoumarin. Copyright © 2007 John Wiley & Sons, Ltd.

Two octahedral complexes of the general formula SnCl 4 · 2(O)PF 2 NR 2 (R = Me ( 1 ) or Et ( 2 )) have been synthesised from SnCl 4 and the ligand R 2 NP(O)F 2 in anhydrous CHCl 3 . The new adducts have been characterised by multinuclear ( 119 Sn, 31 P, 19 F and 1 H) NMR, IR spectroscopy and elemental analysis. When compared with previously described hexamethylphosphoramide (HMPA) and trimethylphosphate (TMPA) analogues, the NMR data of the two complexes prepared suggest the presence of only the cis isomer in solution. Steric factors and the Lewis basicity of the ligand may explain the stereochemistry observed. Low temperature 31 P and 119 Sn NMR spectra show that the compounds partially dissociate in dichloromethane. Additionally, DFT/B3LYP calculations on complex 1 and its ligand have been carried out to support the interpretations of NMR data.

The compound bis(acetylacetonato)dichlorotin(IV) [Sn(acac)2Cl2] forms a distorted octahedral structure involving both oxygen atoms of the acetylacetone group. The two chlorides occupy the cis position, with Sn-Cl distances of Sn1-Cl1 = 2.380(2) A, Sn1-O1 = 2.043(2) A and Sn1-O2 = 2.093(2) A. We report here a new and simple method for the synthesis of Sn(acac)2Cl2, its spectroscopic characterization and, for the first time, we report its crystal structure.

We have developed a new method of N-nitrosation of various secondary and tertiary amines, amides and ureas using a mixture oftin(IV) chloride and sodium nitrate. This method leads to a selective, high-yielding and mild heterogeneous N-nitrosation by in situ generation of nitrosyl chloride (NOCl). The reaction can be carried out in several different solvents such as chloroform, dichloromethane, ethers, ethyl acetate and alcohols, at room temperature.

Trimethyltin(IV)trithiophosphates [(RO)P(S)S2][Sn(Me)3]2 and tributyl tin(IV)trithiophosphates [(RO)P(S)S2][Sn(Bu)3]2 (R=CH3, –C2H5, –C3H7, –C3H7 iso –C4Hn 9, –C4H9 iso, –C4H5 scc, –C5H11 iso C6H11, –C6H5) were prepared in methanolic solution of R3SnCl and dipotassium salt of trithiophosphates in 2:1 molar ratio. These newly synthesised derivatives have been characterized by elemental analysis, molecular weight measurements, IR, 13C, 31P, and 119Sn,NMR spectral studies. Coordination number of four suggested for tin(IV) in these derivatives.

The synthesis of the polysubstituted 8-oxa-1-azaphenalene lactone 4, which embodies the ABCring system of stephaoxocani dine, a tetracyclic isoquinoline alkaloid recently isolated from the tubers of Stephania cepharantha Hayata, is reported. Elaboration of 4 was carried out by means of the camphorsulfonic acid-assisted lactonization of 9, coupled to a titanium(IV) chloridemediated acetal cyclization of the resulting lactone 10 to form the tricyclic intermediate 12, followed by the base-promoted aromatization of the latter to 13 and final benzylic bromination. Lactone 4 constitutes an advanced key intermediate for the total synthesis of stephaoxocanidine, the simplest stephaoxocane.

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.

In the presence of SnCl 4 .5H 2 O, a mixture of thiols and tetraallyltin underwent 1,4- and 1,2-addition, respectively, with the imines derived from 3-alkynals to give (Z)-1-sulfenyl-1,5-alkadien-3-ols in good yields, wherethe hydrolysis of the intermediary imino species was found to be crucial.

trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates when reacted with nitriles in the presence of tin(IV) chloride afford 2,4,5-trisubstituted oxazoles in good to excellent yields. The reactions take place through in situ generation of aroylmethylidene malonates from the cyclopropanes, followed by conjugate addition of nitriles to the malonates to form nitrilium ion intermediates and subsequent cyclisation.

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.

The reaction of benzil with phenol at 180°C in the presence of SnCl4·5H2O produces a benzofuran, a benzofuranol, a benzodifuran, and a benzofuranone. Anhydrous tin(IV) chloride also gives a benzofuranofuranone. Other phenols and their methyl ethers yield related products. The good yields of the benzo- and naphtho-furanones make the method an attractive alternative to the benzilic acid route to such compounds.

2,3,5-Tri- O -benzoyl-β- d -ribofuranosyl cyanide reacts with methyl acetoacetate and diethyl malonate in the presence of stoichiometric amounts of SnCl 4 to give a β- d -ribofuranosyl-enaminoketoester and a β- d -ribofuranosyl-enaminodiester, respectively. The β- d -ribofuranosyl-enaminoketoester was debenzoylated, treated with 2,2-dimethoxypropane and tert -butyl-dimethylsilyl chloride to give the methyl 3-amino-3-(5′- O - tert -butyldimethylsilyl-2′,3′- O -isopropylidene-β- d -ribofuranosyl)-2-acetyl propanoate obtained in good yield together with small amounts of its α-anomer. The reactions of the β-anomer with hydrazine, methyl- and phenylhydrazine, carried out under controlled experimental conditions, afforded the pyrazole C-nucleosides in good yields as β-anomers.

trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates when reacted with nitriles in the presence of tin(IV) chloride afford 2,4,5-trisubstituted oxazoles in good to excellent yields. The reactions take place through in situ generation of aroylmethylidene malonates from the cyclopropanes, followed by conjugate addition of nitriles to the malonates to form nitrilium ion intermediates and subsequent cyclisation.

The reaction of 1,4-dilithiotetraphenylbutadiene with germanium(IV) chloride and tin(IV) chloride affords heterocycles Ph4C4GeCl2, I and Ph4C4SnCl2, II. Compounds I and II, which feature a planar tetraphenylbutadiene backbone, were characterized by elemental analyses, 1H and 13C NMR spectroscopy and single crystal X-ray diffraction. The coordination environments for germanium and tin are distorted tetrahedra with bond angles spanning 35.35° for I and 24.86° for II. The Ge[sbnd]Cl and bond distances are 2.134 A and 2.143 A in I, while the Sn[sbnd]Cl and bond distances are 2.313 A and 2.312 A in II.

The compounds [SnCl 4 (L) 2 ] (where L is urea (u), 1,1-dimethylurea (1,1-dmu), 1,3-dimethylurea (1,3-dmu), tetramethylurea (tmu), thiourea (tu), tetramethylthiourea (tmtu) or 1-allyl-2-thiourea (atu)) were synthesized and characterized by melting points, elemental analysis, thermal studies and IR spectroscopy. The enthalpies of dissolution of the adducts, tin(IV) chloride and ligands 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 reactions (Δ r H θ ), the standard enthalpies of formation (Δ f H θ ), the standard enthalpies of decomposition (Δ D H θ ), the lattice standard enthalpies (Δ M H θ ) and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase (Δ r H θ (g)). The mean standard enthalpies of the tin-oxygen (D(Sn–O)) and tin-sulphur (D(Sn–S)) bonds have been estimated.

Full crystal structures are reported for the tris(o-methoxyphenyl)tin compounds, (o-CH3OC6H4)3SnX [X=Cl (A), F (B)] and [(o-CH3OC6H4)3Sn]2O (C), together with both solid-state and solution (CDCl3) 119Sn NMR data for B and C as well as (Mes)3SnF and [(o-Tol)3Sn]2O. Compound B like A is monomeric with a similar but not identical arrangement of aryl groups around the tin while NMR data indicate that B has almost the same geometry in solution as in the solid state. The anomalously lower frequency δ(119Sn) value for B is consistent with the more ionic character of the SnF bond compared with other SnX (X=Cl, Br, I) bonds. Compound C is the first (Ar3Sn)2O with an SnOSn bond angle between 140 and 180°. The comparison of solid-state with solution 2J(119Sn,119Sn) values for C and [(o-Tol)3Sn]2O suggests that the solid state favours structures having larger SnOSn angles. Reacting C with water gives (o-CH3OC6H4)3SnOH only in solution, identified by its 13C and 119Sn NMR spectra.

In multi-step syntheses involving polyhydroxylated natural products such as carbohydrates that are variously derivatized at different positions, orthogonal removal of one or another type of protecting group is of vital importance. Discrimination of different classes of protecting groups, such as ethers, esters, etc., is often possible with a great degree of success, as for example, selective removal of an 0-acetyl by catalytic transesterification in the presence of an ether protecting group, or hydrogenolytic removal of a benzyl ether protection in the presence of ester groups such as acetates.3 Differentiation of different types of protecting groups within a given class of protecting groups has also been similarly achieved with great success, as for example, hydrogenolytic removal of a benzyl ether group in the presence of a methyl ether.3 However, the situation becomes more challenging when the same protecting group is used to mask more than one position in a polyfunctional molecule and their preferenti...

Using tin(IV) chloride, O -glycosylation reactions were performed on peracylated D-arabinofuranose, d -galactofuranose and l -rhamnofuranose as well as 1-bromo- d -arabinofuranoses at room temperature in good anomeric purities and yields. In these circumstances, this coupling method has certain advantages over standard glycosylation reactions, such as the Koenigs-Knorr methods which use the 1-halosugar (synthesized from the 1-acyl derivative) and toxic mercury salts as the coupling agent.

Direct treatment (1:1) of MCl3 (M = Sc, Y or La) with SnCl4 in thf provides colourless compounds of the type ScSnCl7(thf)5 and MSnCl7(thf)6 (M = Y, La), which have been characterised by elemental analysis and spectroscopic studies. An X-ray determination of ScSnCl7(thf)5 reveals an ionic structure comprising individual six-coordinate [ScCl2(thf)4]+ cations and [SnCl5(thf)]-anions. The cations feature an octahedral metal geometry in which a linear Cl-Sc-Cl unit is surrounded by an equatorial girdle of four solvent (thf) molecules.

The growth response of the alga Chlorella kessleri and the euglenoid Euglena gracilis has been studied as a model system to determine the effects of a tin salt (SnCl 4 .5H 2 O) and of some organotin (OT) derivatives, namely tetrabutyltin (TeBT), tributyltin (TBT) and tributyltin oxide (TBTO). Abiotic degradation was studied as well. Cells were exposed to a toxicity series (0-50 μg/mL -1 ) for the four chemicals in seven-day bioassays. Both micro-organisms are tolerant of the inorganic salt, but growth inhibition was significant for all OT compounds, and especially large for TBT and TBTO. Although C. kessleri and E. gracilis are known to be tolerant towards metals and organic chemicals, the present results show that both are sensitive to organotin compounds: the inhibition of the growth was greater for C. kessleri.

The addition of diorganyl disulfides and dimethyl diselenide to cyclohexene in the presence of tin(IV) chloride proceeded stereoselectively affording trans-adducts of 1:1 composition. No reaction occurs in the absence of tin(IV) chloride.

Several new tetra-aryltin compounds, Ar4Sn (Ar = 3,5-(CH3)2C6H3, 3,5-Z2C6H3, and m-ZC6H4 (Z = F,Cl] and Ar3SnX [X = Cl, Br, I: Ar = 3,5-(CH3)2C6H3, m- and o-CH3OC6H4; X = Br; Ar = m-ZC6H4 (Z = F, Cl)] have been synthesized by literature methods and complete solution NMR data (119Sn, 13C) are reported for these and other meta- and ortho-substituted aryltins. Meta-substituents appear to exert electronic effects on chemical shifts and coupling constants, but for ortho-substituents steric effects appear to predominate. Crystal data show that meta-substituted Ar3SnX have trigonal unit cells in contrast to the monoclinic unit cells adapted by para- and ortho-substituted Ar3SnX. Complete crystal structures are reported for (m-CH3C6H4)3SnCl: R3. a = 14.9262(15), c = 7.3482(12) A , Z = 3 and (3,5-(CH3)2C6H3)3SnCl: R3c, a = 15.119(8), c = 15.593(4) A , Z = 6. In both cases, all molecules have trigonal symmetry, the first such examples to be reported.

Following observations on remote asymmetric induction using allylstannanes, 5-benzyloxy-4-methylpent-2-enylsilanes are also found to react with aldehydes with modest levels of 1,5-induction after treatment with tin(IV) chloride. Transmetallation to give intermediate allyltin trihalides may be involved.

As determined by single crystal X-ray crystallography, SnCl 4 ·2H 2 O and SnCl 4 ·3H 2 O have a molecular structure with cis -[SnCl 4 (H 2 O) 2 ] units linked to each other by a system of hydrogen bonds.

Treatment of oxiranes with hydrogen peroxide and catalytic amounts of SnCl4 yields the corresponding β-hydroxy peroxides.

The reaction of 5-fluorouracil with the seven-membered acetals 1a-g in the presence of tin (IV) chloride, trimethylchlorosilane and hexamethyldisilazane at room temperature gives 1-{[3-(2-hydroxyethylhetero)-1-alkoxy]alkyl}-5-fluorouracils 2a-f and 1-{[2-(3-hydroxypropoxy)-1-isopropoxy]ethyl}-5-fluorouracil 2g in 31–86% yields. The presence of an heteroatom on the 1-position of the cycloacetal and the use of tin (IV) chloride, capable of a 1,4-chelation, seem to impose their influence in the regiospecific ring opening of 1a-g. The conformational analyses carried out on 2b and (1R,3R)-2e and (1R,3S)-2e clearly indicate that the N1(sp2)-C1-C2-C3 moiety tends to fold in a gauche conformation. The antitumour activities of compounds 2b-g were assessed against HEp human cells showing that 2c is 4-fold more active than 5-FU. The drugs studied do not show any clear toxicity in comparison with the toxic effect of 5-FU.

In the presence of SnCl 4 .5H 2 O and acetic acid, a mixture of trimethylsilyl azide and tetraallyltin underwent 1,4- and subsequently 1,2-addition, respectively, with the α,β-unsaturated aldimines to give 1,3-hydroxy azides in good yields, where the hydrolysis of the intermediary imino species was found to be crucial.

Ortho-aminobenzonitriles 1 react with β-ketoesters and alkyl malonates, in the presence of stoichiometric amounts of tin(IV) chloride, to give 4-aminoquinolines 2 and 4-amino-2-quinolones 3 respectively. Similarly β-enaminonitriles 7 afford 4-aminopyridines 8 and 4-amino-2-pyridones 9.

The water-soluble octahedral tin(IV) porphyrin complex, SnCl2tpyp, was synthesized via reaction of H2tpyp with anhydrous SnCl2. The crystal structure of this complex has been determined at room temperature. The tin(IV) atom is coordinated by four nitrogen atoms in a square-planar fashion with an average Sn-Np bond distance of 2.081(9)A, and the coordination sphere is completed by two axial chloro ligands with an average Sn-Cl bond distance of 2.435(5)A, Cl-Sn-Cl = 180.0 (1)°. Crystal data: a = 12.385(12), b = 26.88(2), c = 14.882(9)A, β = 94.16 (7)°, monoclinic, space group C2/c, V = 4941A3, Z = 4, C46H48Cl2N8O6Sn, 2687 observed data, R = 0.085.

The reaction of cyclic enaminonitriles1 with diethyl acetonedicarboxylate (2) affords fused 4-amino-3-ethoxycarbonyl-2-ethoxycarbonylmethyl-pyridines4. The course of the reaction and the yield of cyclic products were promoted by tin(IV)chloride. N-substituted diethyl 3-aminoglutaconates3 seem to be intermediates of the cyclization reaction.

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.

Transmetallation of the 5-benzyloxy-4-methylpent-2-en-1-yl(tributyl)- and -(triphenyl)stannanes 1 and 8 using tin(iv) chloride generates an allyltin trichloride that reacts with aldehydes to give (Z)-1,5-anti-6-benzyloxy-5-methylhex-3-en-1-ols 2. The allyltin trichloride believed to be the key intermediate in these reactions has been trapped by phenyllithium to give anti-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 9. Transmetallation of this anti-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 9 generated an allyltin trichloride that reacted with aldehydes to give the (Z)-1,5-syn-6-benzyloxy-5-methylhex-3-en-1-ols 23 and was trapped by phenyllithium to give syn-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 24. Similar stereoselectivity was observed for tin(iv) chloride promoted reactions of this syn-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 24 with aldehydes and with phenyllithium. The allyltin trichlorides generated by transmetallation of 4-hydroxy- and 4-benzyloxy-pent-2-enyl(triphenyl)stannanes 34 and 35 were similarly trapped by phenyllithium to give 4-hydroxy- and 4-benzyloxy-pent-1-en-3-ylstannanes 36 and 37 whose configurations were established by correlation with known compounds. This work confirmed the configurations of the intermediate allyltin trichlorides involved in tin(iv) chloride promoted reactions of 4- and 5-alkoxypent-2-enylstannanes with aldehydes and showed that the high levels of remote stereocontrol were due mainly to kinetically controlled transmetallation. A fuller mechanistic scheme is proposed for the reactions in the 5-benzyloxy-4-methylpent-2-enylstannane series together with relevant (119)Sn NMR data.

The formal [3+2] cycloaddition of 5-methoxy-2-(p-methoxyphenyl)oxazole with 2(S)-(benzyloxy)-propanal and 2(S)- [(tert-butyldimethylsilyl)- oxy]propanal in the presence of tin(IV) chloride gave cis-(4R,5S,1'S)- and trans-(4S,5S,1'S)-5-(1'-alkoxyethyl)-4-(methoxycarbonyl)-2-(p-me- thoxyphenyl)-2-oxazolines with high diastereoselectivity (94 and 92% selectivity, respectively). A similar reaction of 5-methoxy-2-(p-metho- xyphenyl)oxazole with 2,3-di-O-benzyl-D-glyceraldehyde gave methyl cis- (4S,5R,1'R)-2-(p-methoxyphenyl)-5-[1',2'-bis(benzyloxy)ethyl]-2-oxazo- line-4-carboxylate with high diastereoselectivity (>95% selectivity), and the latter was easily converted to biologically important chiral 2-amino-1,3,4,5-tetrol derivatives

SnCl4 promoted [3+2] cycloaddition reactions of allylsilane to α-keto esters afforded tri- and tetrasubstituted tetrahydrofurans with excellent stereoselectivity via 1,2-silyl migration in good yields.

Transmetallation of (S)-4-benzyloxy-2-pentenyl(tributyl)stannane (I) using tin(IV) chloride generates an allyltin trichloride which reacts in situ with aldehydes to give 1-substituted syn-(3Z)-5-benzyloxyhexenols with excellent stereoselectivity. With chiral aldehydes, the stereoselectivity of the reaction is dominated by the reagent, except for 2-alkoxyaldehydes which show matching and mismatching consistent with preferred Felkin-Anh diastereofacial selectivity

The synthesis of C7- to C16-alkyl maltosides in the presence of tin(IV) chloride as Lewis acid catalyst was performed. The characterization of the products and theoretical investigation of the crucial step in the synthesis were carried out. The preparation of the β-maltosides required reaction time of 1 h, and that of the α-maltosides was 72 h. The side products were the α-D-maltosidechloride and 2-hydroxy-β-maltoside, respectively. The PM3 calculation confirmed the formation of the kinetically controlled β-product. KEY WORDS : Maltose, Synthesis of maltosides, Tin(IV) chloride, PM3 Bull. Chem. Soc. Ethiop. 2011 , 25(1), 83-90.

In the title salt, [Sn(CH3)2Cl(CH4N3S)]Cl, the SnIV atom is five-coordinated in a distorted trigonal-bipyramidal geometry with two methyl groups and one S atom in the equatorial plane, and one N atom and one Cl atom occupying the apical positions. In the crystal, molecules are linked by intermolecular N—H...S hydrogen bonds with set graph-motif C(4) along [010]. N—H... Cl hydrogen bonds with graph-set motif D(2) and D33(10) link cations and anions.

Tin(IV) chloride catalyzed inverse electron demand hetero-Diels-Alder reaction of substituted methyl 2-oxo-3-alkenoates with simple alkenes led to methyl 3,4-dihydro-2H-pyran-6-carboxylates in satisfactory yields. The addition proceeded stereospecifically through an exo transition state.

In the presence of a catalytic amount of tin(IV) species generated from tin(IV) chloride and silver perchlorate, 1-O-acetyl-D-glucose stereoselectively reacts with silyl alkoxides to give the corresponding α-glucosides in high yields.

The cross-coupling reaction of allylstannanes with allylsilanes selectively proceeded in the presence of tin(IV) chloride to give 1,5-dienes. It was found that the substitution of a phenylthio group at γ-position remarkably increased the reactivity of allylstannanes.

SnCl4 promoted [3+2] cycloaddition reactions of allylsilane to α-keto esters afforded tri- and tetrasubstituted tetrahydrofurans with excellent stereoselectivity via 1,2-silyl migration in good yields.

Transmetallation of (S)-4-benzyloxy-2-pentenyl(tributyl)stannane (I) using tin(IV) chloride generates an allyltin trichloride which reacts in situ with aldehydes to give 1-substituted syn-(3Z)-5-benzyloxyhexenols with excellent stereoselectivity. With chiral aldehydes, the stereoselectivity of the reaction is dominated by the reagent, except for 2-alkoxyaldehydes which show matching and mismatching consistent with preferred Felkin-Anh diastereofacial selectivity