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Landfill leachates are an important pool of organotin compounds (OTCs). Several studies have been performed on the occurrence of OTCs in landfill leachates, but only a few of them report degradation and biomethylation processes by bacteria. In the present study transformation of OTCs in landfill leachate was investigated under simulated landfill conditions over a time span of six months. The degradation and biomethylation processes of OTCs were followed by the use of isotopically enriched tin tracers, namely (117)Sn-enriched tributyltin (TBT), (119)Sn-enriched dibutyltin (DBT), (117)Sn-enriched SnCl2, (117)Sn-enriched SnCl4 and a (119)Sn-enriched butyltin mix containing TBT, DBT and monobutyltin (MBT). Transformation of OTCs in spiked leachates was followed at m/z of the enriched spikes and at m/z 120, which allowed simultaneous observation of the transformation of OTCs in the leachate itself and of the added spike. In parallel, these processes were also monitored in a non-spiked leachate sample at m/z 120. Quantification of OTCs was performed by gas chromatography - inductively coupled plasma mass spectrometry (GC-ICP-MS). To discriminate the biotic and abiotic transformations of OTCs and inorganic tin species, sterilization of leachate was also performed and data compared to non-sterilized samples. During the course of the experiment the microbial degradation of TBT was clearly manifested in Sn-enriched spiked leachate samples, while abiotic pathway of degradation was observed for DBT. Biomethylation process was also observed in the leachate spiked with Sn-enriched Sn(2+) or Sn(4+), in concentrations close to those found for total tin in landfill leachates. Monomethyltin (MMeT) was formed first. Stepwise alkylation resulted in dimethyltin (DMeT) and trimethyltin (TMeT) species formation. Hydrolysis of Sn(2+) and Sn(4+) species was found to be a limiting factor which controlled the extent of methyltin formation. The results of the present investigation importantly contribute to a better understanding of the processes that OTCs undergo in leachates, and provide useful information to managers of landfills in taking measures necessary to prevent the release of toxic methyltin species to the nearby environment., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Twenty one novel mixed ligand di-n-butyltin(IV) complexes [(n)Bu2SnAL] (A = substituted 4-acyl-5-pyrazolone, and L = fluorinated benzoic acid) were prepared by condensation of di-n-butyltin(IV) oxide with HL and HA in 1:1:1 molar ratio in refluxing methanol. All of the complexes were characterized by elemental analyses, IR, NMR ((1)H, (13)C, (119)Sn) and in four cases by X-ray diffraction. Cytotoxicity of the compounds was studied against two human cancer cell lines (KB and Hela) by means of the MTT assay compared to cisplatin, featuring IC₅₀ values in the low micromolar range. Hela cancer cell apoptosis-induced by 2 was examined by flow cytometry analysis, and preliminary results showed that 2 at concentrations of more than 1.0 μM can induce apoptosis., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Up to now, the metal complexes with thiocarbonohydrazones have been comparatively rare. Herein, three main group monometallic complexes formulated as [Bi(HL)(NO3)2(H2O)] (1), [Ga(HL)2]OAc·EtOH (2) and [(Ph)2Sn(HL)(OAc)]·DMF (3), where H2L = bis(2-acetylpyrazine)thiocarbonohydrazone, have been synthesized and characterized. The crystal structures of complexes 2 and 3 have been determined by single-crystal X-ray diffraction. Growth inhibition assays have indicated that both the free ligand and the title complexes are capable of inhibiting cell proliferation growth and could slightly distinguish the human hepatocellular carcinoma HepG2 cells from normal hepatocyte QSG7701 cells. Of particular note is the fact that the bismuth(III) complex 1 is the most active compound of this study and is 14-fold more cytotoxic than H2L with an IC50 value of 2.96 ± 0.25 μM. Its possible apoptotic mechanism has been evaluated in HepG2 cells. Complex 1 promotes a dose-dependent apoptosis in HepG2 cells and the apoptosis is associated with an increase in intracellular reactive oxygen species (ROS) production and reduction of mitochondrial membrane potential (MMP).

Six organotin(IV) carboxylates of the type R2SnL2 [R=CH3 (1), n-C4H9 (2), n-C8H17 (3)] and R3SnL [R=CH3 (4), n-C4H9 (5), C6H5 (6), where L=2-(4-ethoxybenzylidene) butanoic acid, have been synthesized and characterized by elemental analysis, FT-IR and NMR ((1)H, (13)C). The complex (1) was also analyzed by single crystal X-ray analysis. The complexes were screened for antimicrobial, cytotoxic and anti-tumor activities. The results showed significant activity in each area of the activity with few exceptions. DNA interactions studies of ligand HL and representative complex 2 were investigated by UV-Visible absorption spectroscopy and viscosity measurements. The results showed that both ligand HL and complex 2 interact with SS-DNA via intercalation as well as minor groove binding., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Di-n-butyl-(2,6-difluorobenzohydroxamato)Tin(IV) (DBDFT), a potential antitumor agent against malignancies, exhibited high activities both in vitro and in vivo. Flow cytometric analysis showed that treatment with DBDFT against Human Gastric Carcinoma (SGC-7901) cells induced a concentration and time-dependent cell accumulation in the G2/M phase of the cell cycle with a parallel depletion of the percentage of cells in G0/G1, the cell apoptosis was observed by characteristic morphological changes and AnnexinV/PI dual-immunofluorescence staining. Fluorescence quantitative FQ- PCR and western blot results showed that G2/M-phase arrest was correlated with up-regulation of cyclin dependent kinase inhibitor p21, Chk2 and CyclinB1, whereas the expressions of other G2/M regulatory check-point protein, Cdc2, and feedback loop protein Cdc25C were obviously down-regulated in a p53-independent manner after the SGC-7901 cells were treated with DBDFT (2.5, 5.0, 7.5 µmol·L(-1)) compared with the control. Furthermore, the up-regulation of Bax and down-regulation of Bcl-2 as well as the activation of caspase-3 were observed, which indicated that DBDFT treatment triggered the mitochondrial apoptotic pathway with an increase of Bax/Bcl-2 ratios, resulting in mitochondrial membrane potential loss and caspase-9 activation in DBDFT treated SGC-7901 cells. In summary, the results illustrated the involvement of multiple signaling pathways targeted by DBDFT in mediating G2/M cell cycle arrest and apoptosis in SGC-7901 cells, which suggested that DBDFT might have therapeutic potential against gastric carcinoma as an effective compound.

Herein a new double O-directed free radical hydrostannation reaction is reported on the structurally complex dialkyldiyne 11. Through our use of a conformation-restraining acetal to help prevent stereocenter-compromising 1,5-H-atom abstraction reactions by vinyl radical intermediates, the two vinylstannanes of 10 were concurrently constructed with high stereocontrol using Ph3SnH/Et3B/O2. Distannane 10 was thereafter elaborated into the bis-vinyl iodide 9 via O-silylation and double I-Sn exchange; double Stille coupling of 9, O-desilylation, and oxidation thereafter furnished 8.

Dimethyltin(IV) complexes with ethanolamine (1) and biologically significant N-glycosides (2 and 3) were designed and synthesized. The structural elucidation of complexes 1-3 was done using elemental and spectroscopic methods; in addition, complex 1 was studied by single crystal X-ray diffraction studies. The in vitro DNA binding profile of complexes 2 and 3 was carried out by employing different biophysical methods to ascertain the feasibility of glycosylated complexes. Further, the cleaving ability of 2 and 3 was investigated by the agarose gel electrophoretic mobility assay with supercoiled pBR322 DNA, and demonstrated significantly good nuclease activity. Furthermore, both the complexes exhibited significant inhibitory effects on the catalytic activity of human Topo I at lower concentration than standard drugs. Computer-aided molecular docking techniques were used to ascertain the mode and mechanism of action towards the molecular target DNA and Topo I. The cytotoxicity of 2 and 3 against human hepatoma cancer cells (Huh7) was evaluated, which revealed significant regression in cancerous cells as compared with the standard drug. The antiproliferative activities of 2 and 3 were tested against human hepatoma cancer cells (Huh7), and results showed significantly good activity. Additionally, to validate the remarkable antiproliferative activity of complexes 2 and 3, specific regulatory gene expression (MMP-2 and TGF-β) was obtained by real time PCR.

The crystal structure of the tetranuclear organotin compound 1,1,3,3,5,5,7,7-octabutyl-7-((E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoyloxy)-4,8-dimethyl-2,4,6,8-tetroxa-1,3,5,7-tetrastannatricyclo[4.2.0.0(2,5)]oct-3-yl (E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoate, [Sn4(C4H9)8(C21H19N2O4)2(CH3O)2(μ3-O)2], consists of a core of three fused Sn2O2 rings. The central ring consists of two Sn atoms each coordinated by two n-butyl chains, two μ3-bridging O atoms and one μ2-bridging methanolate O atom. The peripheral Sn2O2 rings consist of one of the central ring Sn atoms, and an Sn coordinated by one μ3-bridging O atom, one μ2-bridging methanolate O atom, two n-butyl chains and the carboxylate O atom of a (E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoate ligand (L). Despite an apparent centrosymmetric nature, the complex does not crystallize about an inversion centre. The structure packs with π-π interactions between carbazole moieties on adjacent molecules.

The structure of the supramolecular coordination polymer SCP 1; [(n-Bu3Sn)4Fe(CN)6H2O] consists of octahedral [Fe(CN)6](4-) building blocks which are connected by the TBPY-5 configured n-Bu3Sn(CN..)2 fragments creating 3D-network structure. Fenton and photo-Fenton oxidative discoloration of Methylene Blue (MB) has been investigated by hydrogen peroxide catalyzed with the SCP 1. The reaction exhibited pseudo first-order kinetics with respect to each of MB and H2O2. The irradiation of the reaction with UV-light enhanced the rate of MB mineralization, Kobs=0.76 h(-1). Mineralization of MB was investigated by FT-IR spectra. Disodium salt of terephthalic acid photoluminescence probing technology was carried out to identify the reactive oxygen species. The different parameters that affect MB degradation rate were evaluated. Moreover, the efficiency of recycled the SCP 1 and the mechanism of degradation of MB dye were investigated., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Diaryldithiophosphate complexes of mono- and dibutyltin(IV) corresponding to [(ArO)(2)PS(2)(n)Sn(nBu)xCl(4-x-n)] (Ar = o-CH(3)C(6)H(4), m-CH(3)C(6)H(4), p-CH(3)C(6)H(4), 4-Cl-3-CH(3)C(6)H(3), (3,5-CH(3))(2)C(6)H(3); n = 1, 2 for x = 1 and n = 2 for x = 2) were successfully isolated and characterized by elemental analyses, IR, multinuclear NMR ((1)H, (13)C, (31)P and (119)Sn) spectroscopy and X-ray analysis. The thermal properties of the complex [(3,5-CH(3))(2)C(6)H(3)O(2)PS(2)](2)Sn(nBu)(2) (12) have been examined by combined DTA/ DTG thermal analyses. Single crystal X-ray analysis of [(3,5-CH(3))(2)C(6)H(3)O(2)PS(2)](2)S(n)(nBu)(2) (12) revealed that two diaryldithiophosphate ions are coordinated to tin atom in an anisobidentate fashion through the sulfur atoms of each dithiophosphate moiety leading to distorted skew-trapezoidal bipyramidal geometry. The antifungal activity depicts that these complexes are active against fungus Penicillium chrysogenium.

Background: Plastic products improve people's daily life, but microorganisms attaching to plastic product surfaces present health hazards., Aim: Our study aimed to design a new kind of antibacterial plastic products to promote a higher quality of life., Materials and Methods: Antibacterial polyvinyl chloride (PVC) composites were prepared using melt-blending. The antibacterial properties, mechanical properties, and optical transparencies of the PVC composites containing either silver-doped glass or silver-doped zirconium phosphate were studied, and the dispersal of these antibacterial agents throughout the PVC was also observed using scanning electron microscopy., Results: The results showed that the antibacterial agents were well-dispersed throughout the PVC matrix and that the antibacterial ratio of PVC-G against Escherichia coli and Staphylococcus aureus was over 99.0%, which was better than that of PVC-P. The antibacterial agents had little effect on the mechanical properties of the PVC; however, they decreased the optical transparency of PVC, and the transmittance of PVC-P was decreased by 28.3%., Conclusions: Our results indicate that such kinds of antibacterial PVC composites have great potential in a wide variety of safer plastic applications.

A straightforward synthesis of (3-indolyl)stannanes through silver-catalyzed cyclization-stannylation of N-electron-withdrawing group-substituted o-alkynylanilines in the presence of 2-tributylstannylfuran is developed. This method offers several advantages such as no requirement of additional ligands, high efficiency and a wide reaction scope.

α-Stannylated and α-iodinated enamides can easily be obtained by molybdenum-catalyzed regio- and stereoselective hydrostannation and subsequent tin-iodine exchange. These functionalized enamides are interesting building blocks for a wide range of cross-coupling reactions giving access to various types of α-substituted enamides.

The interaction of 3,3-bis(1-methylimidazol-2-yl)propionate (BIMP) with dimethyltin(IV) dichloride (DMT), dibutyltin(IV) dichloride (DBT), and diphenyltin(IV) dichloride (DPT) is investigated at 25°C and 0.1 M ionic strength in water for dimethyltin(IV), and in a 50% dioxane-water mixture for dibutyltin(IV) and diphenyltin(IV). The stepwise formation constants of the 1 : 1 and 1 : 2 complexes formed in solution are calculated from potentiometric measurements using the nonlinear least-square program MINIQUAD-75. The concentration distribution of the various complex species is evaluated as a function of pH. Displacement reactions of the coordinated 3,3-bis(1-methylimidazol-2-yl)propionate by inosine and inosine-5'-monophosphate are investigated from calculations based upon equilibrium properties.

The interactions between glutathione (H3GSH) and (CH3)2Sn(2+), (CH3)3Sn(+), (C2H5)3Sn(+) and (C3H7)3Sn(+) cations were studied by potentiometry, UV spectrophotometry, (1)H NMR spectroscopy and electrospray mass spectrometry (ESI MS). Potentiometric measurements evidenced speciation models very similar for all the alkyltin(IV) cation-GSH(3-) systems, with the formation of M(GSH)(z-3), M(GSH)H(z-2) and M(GSH)H2(z-1) species [M(z+)=(CH3)2Sn(2+), (CH3)3Sn(+), (C2H5)3Sn(+), or (C3H7)3Sn(+)] and, for dimethyltin(IV) cation, also the mixed hydrolytic M(GSH)(OH)(2-) one. The equilibrium behavior in NaCl aqueous solution, at different ionic strengths and temperatures, is discussed. The stability of the species for the dimethyl and trialkyl cations is quite different. As an example, for M(GSH)(z-3), logβ=13.33, 6.55, 6.44 and 5.84, for (CH3)2Sn(2+), (C3H7)3Sn(+), (C2H5)3Sn(+) and (CH3)3Sn(+), respectively (at I=0.1M and t=25°C). The speciation models and the possible structures of the complexes formed are discussed on the basis of spectroscopic and spectrometric results. The sequestering ability of glutathione towards alkyltin(IV) cations was evaluated by determining the concentration of the ligand able to complex half of the metal ion fraction (pL0.5). Glutathione shows a fairly good sequestering ability towards alkyltin(IV) cations, in 10(-3)-10(-5)M range., (© 2013.)

Novel films were prepared by condensation curing reaction of a poly(dimethyl siloxane) (PDMS) matrix with bismuth neodecanoate and dibutyltin diacetate catalysts. An ecotoxicological study was performed on the leachates of the coatings using the bacterium Vibrio fischeri, the unicellular alga Dunaliella tertiolecta, the crustacean Artemia salina and the fish Sparus aurata (larvae) as testing organisms. A copper-based self-polishing commercial paint was also tested as reference. The results showed that the tin-catalysed coatings and the copper paint were highly toxic against at least two of the four test organisms, whereas bismuth-catalysed coatings did not show any toxic effect. Moreover, the same biological assessment was also carried out on PDMS coatings containing a surface-active fluorinated polymer. The toxicity of the entire polymeric system resulted only from the tin catalyst used for the condensation curing reaction, as the bismuth catalysed coatings incorporating the surface-active polymer remained atoxic toward all the tested organisms., (© 2013 Elsevier Inc. All rights reserved.)

Go catalytic! A catalytic enantioselective protonation of alkenyl trifluoroacetates was achieved by using an in situ generated chiral tin bromide methoxide as the chiral catalyst in the presence of methanol. Optically active ketones containing a tertiary stereogenic center at the α-position were obtained with enantioselectivities of up to 94 % ee., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new multicomponent analysis method, based on principal component analysis-multivariate adaptive regression splines (PC-MARS) is proposed for the determination of dialkyltin compounds. In Tween-20 micellar media, dimethyl and dibutyltin react with morin to give fluorescent complexes with the maximum emission peaks at 527 and 520nm, respectively. The spectrofluorimetric matrix data, before building the MARS models, were subjected to principal component analysis and decomposed to PC scores as starting points for the MARS algorithm. The algorithm classifies the calibration data into several groups, in each a regression line or hyperplane is fitted. Performances of the proposed methods were tested in term of root mean square errors of prediction (RMSEP), using synthetic solutions. The results show the strong potential of PC-MARS, as a multivariate calibration method, to be applied to spectral data for multicomponent determinations. The effect of different experimental parameters on the performance of the method were studied and discussed. The prediction capability of the proposed method compared with GC-MS method for determination of dimethyltin and/or dibutyltin., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The removal of triphenyltin chloride from contaminated simulated seawater with adsorption method was discussed. The adsorbents used are fly ash, nSiO2, and nSiO2/fly ash composite. The results showed that the adsorption of the adsorbents increases with increase in the adsorbent dose, contact time, pH, stirring speed, initial TPT concentration, and decreased with increase in temperature. The adsorption fitted well with the Freundlich isotherm, showing that the adsorbent and TPT combined with function groups and the adsorption kinetics followed the pseudo-second-order kinetic model. The thermodynamic parameters were also evaluated. Optimal conditions for the adsorption of TPT from simulated seawater were applied to TPT removal from natural seawater. A higher removal efficiency of TPT (>99%) was obtained for the nSiO2/fly ash composite but not for fly ash and nSiO2.

A 2,5-bis(tributylstannyl)thiophene 1,1-dioxide was prepared from 2,5-bis(trimethylsilyl)thiophene 1,1-dioxide, bis(tributyltin) oxide, and tetrabutylammonium fluoride (TBAF). The 2,5-bis(tributylstannyl)thiophene 1,1-dioxide and a 2,5-diiodothiophene 1,1-dioxide were utilized in a series of Stille cross-coupling reactions to afford thiophene 1,1-dioxides with either electron-donating or electron-withdrawing substituents. Electron-withdrawing groups greatly facilitate the reduction of these sulfone heterocycles, and -C6H4-p-NO2 substituents produce a 510 mV shift as compared to a thiophene 1,1-dioxide with two phenyl groups.

Organotin compounds are the active components of some fungicides, which are potential inhibitors of the F1F0-ATP synthase. The studies about the reaction mechanism might indicate a pathway to understand how these compounds work in biological systems, however, has not been clarified so far. In this line, molecular modeling studies and density functional theory calculations were performed in order to understand the molecular behavior of those compounds when they interact with the active site of the enzyme. Our findings indicate that a strong interaction with His132 can favor a chemical reaction with organotin compounds due to π-π stacking interactions with aromatic rings of organotin compounds. Furthermore, dependence on molecule size is related to possibility of reaction with the amino acid residue His132. Thus, it can also be noticed, for organotin compounds, that substituents with four carbons work by blocking the subunit a, in view of the high energy transition found characterized by steric hindrance.

The tin(II) complexes {LO(x)}Sn(X) ({LO(x)}(-) =aminophenolate ancillary) containing amido (1-4), chloro (5), or lactyl (6) coligands (X) promote the ring-opening polymerization (ROP) of cyclic esters. Complex 6, which models the first insertion of L-lactide, initiates the living ROP of L-LA on its own, but the amido derivatives 1-4 require the addition of alcohol to do so. Upon addition of one to ten equivalents of iPrOH, precatalysts 1-4 promote the ROP of trimethylene carbonate (TMC); yet, hardly any activity is observed if tert-butyl (R)-lactate is used instead of iPrOH. Strong inhibition of the reactivity of TMC is also detected for the simultaneous copolymerization of L-LA and TMC, or for the block copolymerization of TMC after that of L-LA. Experimental and computational data for the {LO(x)}Sn(OR)complexes (OR=lactyl or lactidyl) replicating the active species during the tin(II)-mediated ROP of L-LA demonstrate that the formation of a five-membered chelate is largely favored over that of an eight-membered one, and that it constitutes the resting state of the catalyst during this (co)polymerization. Comprehensive DFT calculations show that, out of the four possible monomer insertion sequences during simultaneous copolymerization of L-LA and TMC: 1) TMC then TMC, 2) TMC then L-LA, 3) L-LA then L-LA, and 4) L-LA then TMC, the first three are possible. By contrast, insertion of L-LA followed by that of TMC (i.e., insertion sequence 4) is endothermic by +1.1 kcal mol(-1), which compares unfavorably with consecutive insertions of two L-LA units (i.e., insertion sequence 3) (-10.2 kcal mol(-1)). The copolymerization of L-LA and TMC thus proceeds under thermodynamic control., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A carboxylic acid ligand, (Z)-4-(4-acetylphenylamino)-4-oxobut-2-enoic acid (APA-1), and its triphenyl-(APA-2) and tributyl-tin(IV) (APA-3) compounds have been synthesized and investigated for their binding with ds.DNA using UV-visible spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements under physiological conditions of pH and temperature. The experimental results from all techniques i.e. binding constant (Kb), binding site size (n) and free energy change (ΔG) were in good agreement and inferred spontaneous compound-DNA complexes formation via intercalation. Among all the compounds APA-3 showed comparatively greater binding at pH 4.7 as evident from its greater Kb values {APA-3: Kb: 5.63×10(4)M(-1) (UV); 7.94×10(4)M(-1) (fluorescence); 9.91×10(4)M(-1) (CV)}. Electrochemical processes of compounds before and after the addition of DNA were found diffusion controlled. Among all compounds, APA-3 exhibited best antitumor activity., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Three new triorganotin(IV) complexes of valproic acid (vp1, Me3Sn-valproate; vp2, Bu3Sn-valproate; vp3, Ph3Sn-valproate) have been synthesized and investigated by spectroscopic and biological methods. An anionic, monodentate valproate ligand was observed, ester-like coordinating the tin atom on a tetra-coordinated, monomeric environment. The structures, though, can distort towards a penta-coordination, as a consequence of a long range O···Sn interaction. Crystallographic and NMR findings confirm this situation both in solid state and solution. Biological finding evidenced a clear cytotoxic action of the complexes in hepatocellular carcinoma cell cultures: one of the complexes induced an 80% cell viability reduction after 24h treatment in HepG2 cells. This effect was accompanied by the appearance of biochemical signs of apoptosis. In Chang liver cells, the same compound induced only modest effects, suggesting a potential use as anti-cancer drug. Preliminary evaluations on hyperacetylation state of histone H3 in tributyltin-valproate treated HepG2 cells showed an increase in Ac-H3 (histone H3 acetylated at lys-9 and lys-14), suggesting that the compound maintains the deacetylation inhibition activity of its ligand valproate., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The effects of triphenyltin (TPT) on non-target aquatic groups like copepods have not yet been studied in detail. Recently, Mesocyclops leuckarti was suggested as a representative species for freshwater cyclopoid copepods to study the effects of plant protection products. We conducted 96h acute toxicity tests in the laboratory to study the effects of TPT on the different life stages of M. leuckarti. We used the recently proposed General Unified Threshold model of Survival (GUTS) to mechanistically describe the underlying toxicokinetic and toxicodynamic process for the nauplii, copepodites and adults (males and females) of M. leuckarti. Experimental results showed that nauplii were significantly more sensitive to TPT compared to the other stages. Also, the 96h LC50 values were much lower than the 48h LC50 values, suggesting that standard acute toxicity test durations for aquatic invertebrates may underestimate toxic effects with respect to compounds like TPT which have a slow mechanism of action. The GUTS analysis, which mechanistically described the toxicity of TPT to the different life stages of M. leuckarti, suggested that the differences in sensitivity were a consequence of a lower threshold of effects in the nauplii compared to a higher threshold in the later stages. This study shows the potential of using the GUTS to understand how toxic compounds interact with different life-stages. Further experiments to provide a more detailed understanding of toxicokinetics of TPT in copepods could be useful., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

UV-Vis. spectrophotometric study of the adduct formation of organotin(IV)trichlorides i.e. PhSnCl3 and MeSnCl3 as acceptors with Co(II) tetraaza complexes, such as [Co(ampen)] [N,N'-ethylenebis-(o-amino-α-phenylbenzylideneiminato)cobalt(II)], [Co(campen)] [N,N'-ethylenebis-(5-chloro-o-amino-α-phenylbenzylideneiminato)cobalt(II)], [Co(amaen)] [N,N'-ethylenebis-(o-amino-α-methylbenzylideneiminato)cobalt(II)], [Co(amppn)] [N,N'-propylene bis-(5-chloro-o-amino-α-phenylbenzylideneiminato)cobalt(II)] and [Co(camppn)] [N,N'-propylenebis-(5-chloro-o-amino-α-phenylbenzylideneiminato)cobalt(II)] as donors were studied spectrophotometrically under N2 atmosphere and in N,N'-dimethylformamide solvent. The formation constants and thermodynamic parameters were measured using spectrophotometric titration of adduct formation at various temperatures. The trend of the adduct formations of the cobalt(II) tetraaza complexes with a given organotintrichloride acceptor decreases as follow: [Co(amaen)]>[Co(amppn)]>[Co(ampen)]>[Co(camppn)]>[Co(campen)]. The trend of the formation constants for the studied organotintrichlorides with a given cobalt(II) tetraaza complexes is as follow: PhSnCl3>MeSnCl3., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Three diorganotin(IV) complexes of the general formula R2Sn[RcC(O)N(RN)O] (Rc = aryl, RN = Alkyl) have been synthesized by refluxing in toluene the corresponding diorganotin(IV) oxides with the free ligand N-methyl p-fluorobenzohydroxamic acid, using a Dean and Stark water separator. The ligand was derived from the reaction of the corresponding p-fluorobenzoyl chloride and N-methylhydroxylamine hydrochloride in the presence of sodium hydrogen carbonate. The isolated free ligand and its respective diorganotin compounds have been characterized by elemental analysis, IR and 1H-, 13C-, 119Sn-NMR spectroscopies. The crystal structures of the diorganotin complexes have been confirmed by single crystal X-ray diffraction methods. The investigations carried out on the diorganotin(IV) complexes of N-methyl p-fluorobenzohydroxamic acid confirmed a 1:2 stoichiometry. The complex formation took place through the O,O-coordination via the carbonyl oxygen and subsequent deprotonated hydroxyl group to the tin atom. The crystal structures of three diorganotin complexes were determined and were found to adopt six coordination geometries at the tin centre with coordination to two ligand moieties.

A new synthetic scheme towards silica-supported organotrichlorotin derivatives has been developed. It involves the synthesis of (11-triethoxysilyl)undecyltricyclohexyltin, followed by sol-gel processing and, subsequently in the formation of the resulting hybrid silica, by electrophilic substitution of the tricyclohexyltin function by the target grafted trichlorotin using tin tetrachloride. HR-MAS (119)Sn and CP-MAS (29)Si NMR combined with N2-sorption and TEM measurements evidenced the formation of a mesoporous organic-inorganic hybrid silica including a functionally pure supported-organotrichlorotin species. This silica-grafted organotrichlorotin displays a satisfactory catalytic activity in the transesterification of ethyl acetate by 1-octanol. The catalyst could be recycled four times without significant loss of activity. Furthermore, tin leaching below 10 ppm evidences the benefits of the proposed strategy to limit tin contamination of the final products.

Gas-phase interactions of organotins with glycine have been studied by combining mass spectrometry experiments and quantum calculations. Positive-ion electrospray spectra show that the interaction of di- and tri-organotins with glycine results in the formation of [(R)2Sn(Gly)-H](+) and [(R)3Sn(Gly)](+) ions, respectively. Di-organotin complexes appear much more reactive than those involving tri-organotins. (MS/MS) spectra of the [(R)3Sn(Gly)](+) ions are indeed simple and only show elimination of intact glycine, generating the [(R)3Sn](+) carbocation. On the other hand, MS/MS spectra of [(R)2Sn(Gly)-H](+) complexes are characterized by numerous fragmentation processes. Six of them, associated with elimination of H2O, CO, H2O + CO and formation of [(R)2SnOH](+) (-57 u),[(R)2SnNH2](+) (-58 u) and [(R)2SnH](+) (-73 u), are systematically observed. Use of labeled glycines notably concludes that the hydrogen atoms eliminated in water and H2O + CO are labile hydrogens. A similar conclusion can be made for hydrogens of [(R2)SnOH](+) and [(R2)SnNH2](+) ions. Interestingly, formation [(R)2SnH](+) ions is characterized by a migration of one the α hydrogen of glycine onto the metallic center. Finally, several dissociation routes are observed and are characteristic of a given organic substituent. Calculations indicated that the interaction between organotins and glycine is mostly electrostatic. For [(R)2Sn(Gly)-H](+) complexes, a preferable bidentate interaction of the type η(2)-O,NH2 is observed, similar to that encountered for other metal ions. [(R)3Sn](+) ions strongly stabilize the zwitterionic form of glycine, which is practically degenerate with respect to neutral glycine. In addition, the interconversion between both forms is almost barrierless. Suitable mechanisms are proposed in order to account for the most relevant fragmentation processes., (Copyright © 2013 John Wiley & Sons, Ltd.)

The first catalytic radical coupling of iodomethylphosphorus compounds was accomplished with allyl-, alkenyl-, and allenylstannanes under UV irradiation in the presence of an indium(III) halide catalyst, for which a transmetalated allylic indium species was confirmed to be an active radical species.

The review purposes are to (1) evaluate the experimental evidence for adverse effects on reproduction and metabolism and (2) identify the current knowledge of analytical procedures, biochemistry and environmental aspects relating to organotins. Organotins are pollutants that are used as biocides in antifouling paints. They produce endocrine-disrupting effects in mollusks, such as imposex. In rodents, organotin exposure induces developmental and reproductive toxicity as well as alteration of metabolic homeostasis through its action as an obesogen. The adverse effects that appear in rodents have raised concerns about organotins' potential health risk to humans in relation to organotin exposure. At present, triorganotin, such as tributyltin, have been demonstrated to produce imposex, and mammalian reproductive and metabolic toxicity. For most mammals, triorganotin exposure predominantly occurs through the ingestion, and this compound can cross the placenta. With these risks in mind, it is important to improve our knowledge of organotins' effects on environmental health., (Copyright © 2012 Elsevier Inc. All rights reserved.)

A catalytic process for the chemo- and regioselective functionalization of nonprotected carbohydrates has been developed. This novel process allows selective thiocarbonylation, acylation, and sulfonylation of a particular hydroxy group in a particular carbohydrate in the simultaneous presence of structurally similar carbohydrates such as anomers. In addition, the chemoselectivity can be switched by regulating only the length of the alkyl chain in the organotin catalyst.

A novel double Migita-Kosugi-Stille coupling reaction with dihydrostannolanes, which are readily available from a radical cascade reaction, was achieved with dihalobenzenes in the presence of a palladium catalyst. Use of unsymmetrical 1-bromo-2-iodobenzene derivatives accomplished the double coupling reaction which gave tetrahydrobenz[f]isoindoles in a regioselective manner.

A method based on headspace sorptive extraction (HSSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed for the simultaneous determination of six organotin compounds (OTCs), corresponding to mono- and di-substituted methyltin, butyltin and octyltin species. Several parameters affecting both the headspace extraction and thermal desorption steps were carefully optimized using multivariate designs. Analytes were derivatized by in situ ethylation with sodium tetraethylborate. The optimized method was applied to the analysis of water samples of different origins, as well as to checking the migration of the studied compounds from commercially available plastic containers to the adequate liquid simulant. Quantification was carried out against aqueous calibration curves using diphenyltin as internal standard, providing detection limits of between 1.7 and 7.0 ng(Sn) L(-1), depending on the compound, and repeatabilities lower than 10% in terms of relative standard deviation. The applicability of the method was assessed by means of recovery studies and satisfactory values for all compounds were attained. The release of OTCs from the tested packages to the liquid simulant was confirmed, concentrations as high as 2.4 μg(Sn) L(-1) being found for dioctyltin. Even though the proposed method was developed for organotin halides, its application to an organotin ester shows its suitability for determining these compounds in migration assays., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A reinvestigation of Pd-catalysed alkyne (R'-C≡CH; R' = H, Ph) insertion chemistry involving R(3)SnSnR(3) (3a: R = Me; 3b: R = n-Bu) was undertaken. Model distannyl ethylenes 4a-b (Me(3)SnCH=CR'SnMe(3)) and 5a-b ((n-Bu)(3)SnCH=CR'Sn(n-Bu)(3)) were reproduced and further characterized by NMR ((119)Sn, (13)C, (1)H) and UV-Vis spectroscopy. In the presence of an excess of phenylacetylene, dimerization-carbostannylation of compound 4b yielded the new conjugated butadiene, (Z,Z)-1,4-bis(trimethylstannyl)-1,4-diphenyl-buta-1,3-diene (9). An X-ray structure determination of 9 reveals a symmetrical double-bond Z confirmation. Compound 9 was further characterized by NMR, UV-Vis spectroscopy, and MS. A DFT analysis of model compounds (4a-b, 5a-b, 9) and the experimental and theoretical λ(max) values from the UV-Vis spectra were also compared. Acetylene and phenylacetylene Pd-catalysed insertion into the backbone of poly[di-(n-butyl)]stannane 12 resulted in new, modest molecular weight, partially inserted alkene tin polymers (13a-b) that were also characterized by GPC, NMR, UV-Vis spectroscopy and elemental analysis.

Various R/Ar-functionalized tin 5,10,15-tris(pentafluorophenyl)corrolate derivatives are reported herein including the first ferrocenyltin corrolate species. The isopropyl, sec-butyl-, 2-methyl-n-butyl-, phenyl-, 2-thienyl-, and ferrocenyltin species have been prepared and characterized through (1)H, (13)C, and (119)Sn HMQC NMR spectroscopy, mass spectrometry, UV-vis and photoluminescent spectroscopy, and cyclic voltammetry studies. J(C/H-Sn) NMR spectroscopic couplings and ring-current effects (upfield shifting) were determined for the R-Sn axial hydrogen and carbon atoms. This report adds to older conceptually similar reports, by, i.e., Janson et al. (J. Am. Chem. Soc. 1969, 91, 5210) and Walker et al. (J. Am. Chem. Soc.1983, 105, 6923-6929), as discussed herein. Such NMR spectroscopic aspects are discussed for these model systems. Compound Sn-Ph bond cleavage was achieved by treatment with I(2).

Thioredoxin reductase (TrxR) is overexpressed in cancer cells and is therefore a putative cancer target. Inhibition of this enzyme is considered an important strategy for the development of new chemotherapeutic agents with a specific mechanism of action. Organotin compounds have been described as experimental antitumor agents, yet their mechanism of action remains largely unknown. Based on the outcome of a virtual screening study, various di- and tri-n-butyltin(IV) carboxylates were synthesized, and their biological properties were evaluated. All synthesized compounds were able to inhibit TrxR selectively within the micromolar range and showed potent antitumor activity against HT-29 and MCF-7 cancer cell lines. Moreover, tin(IV) organometallics were found to strongly induce apoptosis in the BJAB lymphoma cell line. Mass spectrometry and atomic absorption spectroscopy experiments revealed metal binding to proteins, and efficient cellular uptake was observed using a di-n-butyltin(IV) complex as an example., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Asymmetric catalysis under almost-neutral reaction conditions is key for the efficient synthesis of optically active polar molecules. We have developed catalytic enantioselective reactions of acyclic or cyclic alkenyl esters by using an (S)-BINOL-derived chiral tin-dibromide reagent that possesses a bulky aryl group at the 3 or 3' position as the chiral pre-catalyst in the presence of a sodium alkoxide and an alcohol, in which a chiral tin alkoxide bromide is generated in situ and recycled with the assistance of an alcohol. In this Personal Account, we describe three types of asymmetric transformation that proceed through a chiral tin enolate: 1) The asymmetric aldol reaction of alkenyl esters or unsaturated lactones with aldehydes or isatins; 2) the asymmetric three-component Mannich-type reaction of alkenyl esters and related cycloaddition reactions; and 3) the asymmetric N-nitroso aldol reaction of unsaturated lactones with nitrosoarenes., (Copyright © 2013 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

α-Amino acids are essential resources for human life and are highly useful as building blocks for organic synthesis. The core framework of an α-amino acid can be divided into three basic components: an aldehyde, an amine, and carbon dioxide (CO(2)). We report herein that a one-step synthesis of α-amino acids has been successfully achieved from these three basic and inexpensive chemicals with a single operation, in which the mixture of an aldehyde, a sulfonamide, and gaseous CO(2) was heated at 100 °C in the presence of Bu(3)Sn-SnBu(3) and CsF. In this one-pot sequential protocol, two important intermediates (imine and α-amino stannane) are involved and the stannyl anion generated in situ plays a crucial role, particularly for the efficient stannylation of the imine in the presence of proton sources and for promoting retrostannylation of the undesired α-alkoxy stannane owing to its high stability and tolerance of the presence of proton sources. This methodology enabled the synthesis of a wide range of racemic arylglycine derivatives in high yields., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An original access to iminosugars from a cis/trans mixture of stannylated oxazolidinones 5 is reported. The dehydropiperidines 7-trans and 7-cis were obtained stereoselectively with an RS and SS configuration depending on the order of the Sn-Li transmetalation (followed by electrophilic trapping) and of the ring closing metathesis reactions due to the stereoselective epimerization of the α-aminoanion intermediate. The dehydropiperidines 7-trans and 7-cis were subsequently used for the synthesis of enantiopure homonojirimycin analogs.

Organotin complexes are recognized as the biologically active compounds in inducing cancerous cells death at very low doses. To date, organotin compounds currently appear among the most potent candidates in research related to the new anticancer drugs. In this study, new organotin(IV) N-butyl-N-phenyldithiocarbamate compounds have been successfully synthesized between the reaction of N-butylaniline amine with organotin(IV) chloride in 1:2/1:1 molar ratio. All compounds were characterized using the elemental analysis, FT-IR and NMR spectroscopy. The single crystal structure was determined by X-ray single crystal analysis. The elemental analysis showed good agreement with the suggested formula (C4H9)2Sn[S2CN(C4H9)(C6H5)]2 (Compound 1 and 2), (C6H5)2Sn[S2CN(C4H9)(C6H5)]2 (Compound 3) and (C6H5)3Sn[S2CN(C4H9)(C6H5)] (Compound 4). The important infrared absorbance peaks, v (C = N) and v(C = S) were detected in range between 1457-1489 cm(-1) and 951-996 cm(-1), respectively. The chemical shift of carbon in NCS2 group obtained from 13C NMR was found in range 198.86-203.53 ppm. The crystal structure of compound 4 showed that the dithiocarbamate ligand coordinates in a monodentate fashion. It crystallized in monoclinic P2(1)/n space group with the crystal cell parameter: a = 10.0488(1) angstroms, b = 18.0008(2) angstroms, c = 15.2054(2) angstroms, beta = 102.442(1) degrees and R = 0.044. The cytotoxicity (IC50) of these compounds against Jurkat E6.1 and K-562 leukemia cells were in the range between 0.4-0.8 and 1.8-5.3 microM, respectively as assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazholium bromide (MTT) assay. In conclusion, our study demonstrate that all compounds showed potent cytotoxicity towards both cell lines tested with the triphenyltin(IV) compound displayed the greatest effect.

The title compound, [Sn(CH(3))(2)(C(16)H(15)NO(3))], crystallized from one reaction batch with high enantiomeric excess as both a pure enantiomer and a racemate. The S enantiomer crystallizes in the chiral space group P3(2). The racemate crystallizes in the space group P1 with R and S enantiomers in the crystal lattice; these form dimers about a crystallographic inversion centre.

Tri-and diorganotin(IV) orotates of general formula, R(n)Sn(H(2)Or)(m) [n = 3/2, m = 1/2, R = Me, n-Bu, n-Oct and Ph; H(2)Or(-) = monoanion of orotic acid (H(3)Or)] (n-Bu(2)Sn(HOr) as an exception) have been synthesized. On the basis of various spectroscopic studies it is revealed that R(3)Sn(H(2)Or) and R(2)Sn(H(2)Or)(2) exhibit distorted trigonal-bipyramidal and distorted octahedral geometry, respectively, and n-Bu(2)Sn(HOr) shows both five and six coordination geometry around tin. In vitro anti-cancer screening against MCF-7 (mammary), HEK-293 (kidney), PC-3 (prostate), HCT-15 (colon) and HepG-2 (liver) cancer cell lines suggest that the n-Oct(2)Sn(H(2)Or)(2) is the most active complex among all of the studied complexes. DNA fragmentation and antioxidant enzyme assays suggest that cytotoxic effect of the complexes is selectively mediated through the induction of apoptosis. They also exhibit low toxicity and good anti-inflammatory activity (in vivo)., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

The reaction of pseudo-ortho-4,12-N,N'-diphenyldiamino-[2.2]paracyclophane ((±)-3) with Sn[N(SiMe(3))(2)](2) results in the formation of the monomeric planar chiral N-heterocyclic stannylene (±)-4, featuring a unique [2.2]paracyclophane backbone, which has been characterized by an X-ray diffraction study.

The reaction of 2,2-dimethoxy-N-methylethyllamine or 2-methyl-1,3-dioxolane with CS(2) in alkaline media produced two novel dithiocarbamate salts. Subsequent reactions with organotin halides yielded six new complexes: [SnMe(2){S(2)CNR(R(1))(2)}(2)] (1), [Sn(n-Bu)(2){S(2)CNR(R(1))(2)}(2)] (2), [SnPh(2){S(2)CNR(R(1))(2)}(2)] (3), [SnMe(2){S(2)CNR(R(2))(2)}(2)] (4), [Sn(n-Bu)(2){S(2)CNR(R(2))(2)}(2)] (5), [SnPh(2){S(2)CNR(R(2))(2)}(2)] (6), where R = methyl, R(1) = CH(2)CH(OMe)(2), and R(2) = 2-methyl-1,3-dioxolane. All compounds were identified in terms of infrared, (1)H and (13)C NMR, and the complexes were also characterized using (119)Sn NMR, (119)Sn Mössbauer and X-ray crystallography. The biological activity of all derivatives has been screened in terms of IC(90) and IC(50) against Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus, Penicillium citrinum, Curvularia senegalensis, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Streptococcus sanguinis, Escherichia coli, Citrobacter freundii, Salmonella typhimurium, and Pseudomonas aeruginosa and the results correlated well with a performed study of structure-activity relationship (SAR). Complexes (3), (5) and (6) displayed the best IC(90) and IC(50) in the presence of the fungi, greater than that of miconazole, used as control drug., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Two series of new diorganotin(IV) cycloalkylhydroxamate complexes with different ring sizes (cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl), formulated as the mononuclear [R(2)Sn(HL)(2)] (1:2) (a, R=(n)Bu and Ph) and the polymeric [R(2)SnL](n) (1:1) (b, R=(n)Bu) compounds, were prepared and fully characterized. Single crystal X-ray diffraction for [(n)Bu(2)Sn{C(5)H(9)C(O)NHO}(2)] (3a) discloses the cis geometry and strong intermolecular NH⋯O interactions. The in vitro cytotoxic activities of the complexes were evaluated against HL-60, Bel-7402, BGC-823 and KB human tumour cell lines, the greater activity concerning [(n)Bu(2)Sn(HL)(2)] [HL=C(3)H(5)C(O)NHO (1a), C(6)H(11)C(O)NHO (4a)] towards BGC-823. The complexes undergo, by cyclic voltammetry and controlled-potential electrolysis, one irreversible overall two-electron cathodic process at a reduction potential that does not appear to correlate with the antitumour activity. The electrochemical behaviour of [R(2)Sn{C(5)H(9)C(O)NHO}(2)] [R=(n)Bu (3a), Ph (7a)] was also investigated using density functional theory (DFT) methods, showing that the ultimate complex structure and the mechanism of its formation are R dependent: for the aromatic (R=Ph) complex, the initial reduction step is centred on the phenyl ligands and at the metal, being followed by a second reduction with SnO and SnC ruptures, whereas for the alkyl (R=(n)Bu) complex the first reduction step is centred on one of the hydroxamate ligands and is followed by a second reduction with SnO bond cleavages and preservation of the alkyl ligands. In both cases, the final complexes are highly coordinative unsaturated Sn(II) species with the cis geometry, features that can be of biological significance., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Reactions of the diorganotin with two N-OH diimide ligands (N-hydroxyphthalimide and N-hydroxysuccinimide) yielded five new dimeric tetraorganostannoxanes formulated as R(8)Sn(4)O(2)L(2)X(2). The crystal structures of the complexes reveal the formation of the tetranuclear species contains a planar Sn(4)O(4) core, consisting of three adjacent rhombs with bridging oxo and N-OH diimide ligands. The central tin atoms are five-coordinated to assume a distorted trigonal bipyramidal configuration and the N-OH diimide ligands act as monodentate O-bound planar. In vitro cytotoxic activities of the title compounds have been determined against three cell lines (A549, HCT-8 and HL-60). Studies reveal that three di-n-butyltin(IV) diimido complexes show higher cytotoxic activities than cisplatin. The structure-activity relationship of the cytotoxicity of the title complexes has also been discussed., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Regio- and stereoselective installation of boryl and stannyl moieties into a carbon-carbon triple bond of various alkynes has been achieved based on a three-component coupling reaction by using a diboron and a tin alkoxide with the aid of a copper(II) acetate-tricyclohexylphosphine complex, giving diverse vic-borylstannylalkenes in a straightforward manner. Carbon-tin and carbon-boron bonds of the resulting borylstannylation product are successively transformed into carbon-carbon bonds by a Migita-Kosugi-Stille and a Suzuki-Miyaura coupling, leading to the formation of (Z)-tamoxifen with anti-breast cancer activity., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two syntheses of the C(7)–C(16)-fragment 41 of epothilone D 2 were developed that were based on tin(IV) bromide mediated reactions of 5,6-difunctionalised hex-2-enylstannanes with aldehydes. In the first synthesis, (5S)-6-tert-butyldimethylsilyloxy-5-hydroxy-2-methylhex-2-enyl(tributyl)stannane 20 was reacted with (E)-but-2-enal to give (2S,7R,4Z,8E)-1-tert-butyldimethylsilyloxy-5-methyldeca-4,8-diene-2,7-diol 26 containing ca. 20% of its (7S)-epimer. Following desilylation, the crystalline (2S,7R)-triol 32 was protected as its acetonide 33 and esterified to give the (4-methoxybenzyloxy)acetate 34. An Ireland–Claisen rearrangement of this ester gave methyl (2R,3S,10S,4E,7Z)-3,7-dimethyl-10,11-(dimethylmethylene)dioxy-2-(4-methoxybenzyloxy)undeca-4,7-dienoate 35 that was converted into (2S,9S,6Z)-2,6-dimethyl-9,10-(dimethylmethylene)dioxydec-6-en-1-ol 41 by regioselective alkene manipulation, ester reduction and cleavage of the resulting terminal diol 40 with a reductive work-up. The second synthesis involved the tin(IV) bromide mediated reaction between the stannane 20 and (3S)-4-(4-methoxybenzyloxy)-3-methylbutanal 44 that gave (2S,7S,9S,4Z)-1-tert-butyldimethylsilyloxy-5,9-dimethyl-10-(4-methoxybenzyloxy)dec-4-ene-2,7-diol 45 containing ca. 20% of its (7R)-epimer. After desilylation and protection of the vicinal diol as its acetonide 46, a Barton–McCombie reductive removal of the remaining hydroxyl group gave the (2S,9S,6Z)-2,6-dimethyl-9,10-(dimethylmethylene)dioxydec-6-en-1-ol 41 after oxidative removal of the PMB-ether. The first of these syntheses uses just one chiral starting material, but the second is shorter and more convergent. It was therefore modified by the use of (5S)-6-tert-butyldimethylsilyloxy-5-(2-trimethylsilylethoxy)methoxy-2-methylhex-2-enyl(tributyl)stannane 49 that reacted with (3S)-4-(4-methoxybenzyloxy)-3-methylbutanal 44 to give a 50:50 mixture of the C(4)-epimers of (2S,9S,6Z)-10-tert-butyldimethylsilyloxy-1-(4-methoxybenzyloxy)-2,6-dimethyl-9-(2-trimethylsilylethoxy)methoxydec-6-en-4-ol 50 with high fidelity for formation of the (Z)-alkene. Following the Barton–McCombie deoxygenation, the product 52 was taken through to (2S,9S,6Z,10E)-2,6,10-trimethyl-11-(2-methyl-1,3-thiazol-4-yl)-9-(2-trimethylsilylethoxy)methoxyundeca-6,10-dienal 59 that corresponded to the fully functionalised C(7)–C(17) fragment of epothilone D 2. A precedented stereoselective aldol condensation followed by O-protection, selective deprotection, oxidation and macrocyclisation then gave the macrolide 71 that was deprotected to complete a synthesis of epothilone D 2. Finally regio- and stereo-selective epoxidation gave epothilone B 1.

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.