Tin acetal

The production of triphenyl tin hydroxide [76-87-9] and triphenyl tin acetate [900-95-8] start with triphenyl tin chloride, which is prepared by the Kocheshkov redistribution reaction from tetraphenyltin and tin tetrachloride. The hydroxide is prepared from the chloride by hydrolysis with aqueous sodium hydroxide. The acetate can be made directiy from the chloride using sodium acetate or from the hydroxide by neutrali2ation with a stoichiometric quantity of acetic acid. 

Tricyclohexyltin hydroxide is metabolized in vivo to inorganic tin via di- and monocyclohexyltin derivatives (502), and in vitro studies suggested that the major, metabolic reaction is carbon-hydroxylation of the cyclohexyl group (503). Studies in vivo using either tri-phenyl[ Sn]tin acetate (467) or triphenyl[" Sn]tin chloride (504) in rats showed that these compounds are metabolized to yield substantial amounts of di- and monophenyltin derivatives, although no significant quantities of hydroxylated metabolites have been identified (503) in this case. 

The establishment of the equilibrium is often accelerated by acidic or basic catalysts, for example, by strong acids (p-toluenesulfonic acid), metal oxides (antimony trioxide), Lewis acids (titanium tetrabutoxide, tin acetates or tin oc-toates), weak acid salts of alkali metals or alkaline earth metals (acetates, benzoates), or by alcoholates. 

In solution, the tin acetates CH3COO(CH2)nSnCl3(n = 3-5)110 exist as a mixture of a monomer with intramolecular coordination (Section VILA) and an oligomer with intermolecular coordination in fast equilibrium on the 1H, 13C and 119Sn NMR time... 

TINESTAN TINESTAN 60 WP TIN TRIPHENYL ACETATE TPTA TPZA TRIFENYLTINACETAAT (DUTCH) TRIPHENYLACETO STANNANE TRIPHENYL-TIN ACETATE TRIPHENYL-ZINNACETAT (GERMAN) TUBOTIN VP 1940... 

Annulation to carbonyl functions has also been achieved with Trost s bifunctional reagents. Whereas the parent silyl acetate (97) yields only simple alkylation products with aldehydes under normal conditions, addition of only a few mole % of trimethyltin acetate to the reaction mixture results in facile formation of methylenetetrahydrofurans Furthermore, excellent diastereoselectivity is observed in the cycloaddition to a galactose-derived aldehyde (125) (equation 136). The tin acetate co-catalyst also promotes addition to relatively unreactive ketone carbonyls, such as in the case of benzofuran (126) and the acetylenic ketone (127) (equations 137, 138). It is remarkable that even the sterically hindered enone (128) reacts preferentially at the ketone function (equation 139). A tributyltin analog (129) of (97) has been used in the stepwise formation of a methylenetetrahydrofuran from aldehydes. Similarly, pyrrolidines can be prepared from the corresponding imines in two steps via a Lewis acid-catalyzed 1,2-addition of the tin reagent, which is then followed by a Pd-catalyzed cyclization (equation 140). Direct formation of pyrrolidine from the imine is possible if one uses a mesylate analog of (97) and a nickel(O) catalyst (equation 141). ... 

It is difficult to compare these results with those given in the literature for other substances using different testing procedures [77]. However, the use of triphenyl tin acetate has previously been studied under similar conditions to those described herein with a FRso=0.37 when the assay dose was 10 pg/cm2 [18, 81]. Therefore, more than eight of the new products in principle appear to be more active than triphenyl tin acetate, which is the standard for antifeedant assays. 

The diol 19 (1 mmol) was taken up in dry benzene (or toluene) (40 mL) and the dibutyltin dimethoxide (1.1 mmol) added in one portion. Benzene (20 mL) was then removed by distillation and the tin acetal solution allowed to cool to r.t.To the solution was added benzyl bromide (1.1 mmol) and tetra-N-butylammonium iodide (1.5 mmol) and the temperature was then raised to 50 °C and maintained until the reaction was complete by TLC. The reaction mixture was quenched by the addition of water (10 mL) and standard worked-up. The crude was purified by flash chromatography on silica gel to give 20 (83%). 

Scheme 20. Synthesis of the F-ring tin acetal building block 68.

Fig. 23.9 Dependence of the Sn02 crystallite average size on the time of isothermal heating at 700 °C (1) Sn02 nanopowder prepared by precipitation from tin acetate solution (2) Sn02 doped by S (0.036 wt%) (3) Sn02 doped by Cl (0.038 wt%) (4) Sn02 with surface modified by Pd (1.2 wt%) (5) Sn02 doped by Pd (0.024 wt%) (6) commercial Sn02 nanopowder from Sigma-Aldrich (specific surface area-45 mYg) (Data from Pavelko et al. 2009a, b)...

A proposed mechanism for the cycloaddition with carbonyl compounds is depicted in Scheme 25.The TMM-Pd intermediate reacts with carbonyl group to give rise to the zwitterionic rj -allylpaUadium complex. Addition of the tin acetate leads to the formation... 

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