Tin derivatives

Ph3SnCl and propargylmagnesium bromide give a 90 10 mixture of the acetylenic and allenic tin derivatives, while in the case of Me3SnCl this ratio is 30 70 . 

Perfluoroalkylacecylenic tin compounds have been synthesized via the reaction of perfluoroalkylacetylenic Grignard reagents with tin halide derivatives [21] (equation 14) The stability of several of these perfluoroalkylacetylenic tin derivatives has been studied [22],... 

Allyltin compounds can also be formed by elimination from the tin derivatives of allyldialkylcarbinols (145). 

As a recent result an example of C- and 0-covalently bonded tin substituted ylides (respectively 90 and 91) has been reported, the adducts resulting from the reaction of a stabilized yldiide with tin derivatives (RjSnCl, R2SnCl2, or SnCl2) (Scheme 28) [64]. 

Reaction conditions that involve other enolate derivatives as nucleophiles have been developed, including boron enolates and enolates with titanium, tin, or zirconium as the metal. These systems are discussed in detail in the sections that follow, and in Section 2.1.2.5, we discuss reactions that involve covalent enolate equivalents, particularly silyl enol ethers. Scheme 2.1 illustrates some of the procedures that have been developed. A variety of carbon nucleophiles are represented in Scheme 2.1, including lithium and boron enolates, as well as titanium and tin derivatives, but in... 

The enolates of other carbonyl compounds can be used in mixed aldol reactions. Extensive use has been made of the enolates of esters, thiol esters, amides, and imides, including several that serve as chiral auxiliaries. The methods for formation of these enolates are similar to those for ketones. Lithium, boron, titanium, and tin derivatives have all been widely used. The silyl ethers of ester enolates, which are called silyl ketene acetals, show reactivity that is analogous to silyl enol ethers and are covalent equivalents of ester enolates. The silyl thioketene acetal derivatives of thiol esters are also useful. The reactions of these enolate equivalents are discussed in Section 2.1.4. 

Other heteropolynuclear gold(II) complex that can be obtained by replacement of halide groups in bis(ylide)gold(II) species by other anionic nucleophilic metal complex is the tin derivative [Au2 Sn[N(p-Tol)SiMe2]3SiMe 2 M-(CH2)2PPh2 2] (350).2041... 

The two acetylenic functions in the silicon or tin derivative make possible a competition between 1 1 and 2 1 reactions (Scheme 39, pathway b), and the product ratio depends significantly on the reaction conditions. For silicon derivatives an excess of 1-boraadamantane in the reaction mixture (acetylenic component added to 1-boraadamantane) leads to the octacyclic compounds 88 (up to 60%), while when the much more reactive 1-alkynyltin analogues are used, a second intramolecular 1,1-organoboration often takes place <2001CEJ775>. The stmcture of 88c (M = Sn, R = Me, R1 = SiMe3) was confirmed by X-ray analysis <2001CEJ775>. 

The resistance of the E14-S bond in cyclotrimetallathianes toward nucleophilic reagents, for example, water and alcohol,62 increases on going from the silicon compounds to the corresponding germanium and tin derivatives. This is due, most likely, to the fact that the reaction of less nucleophilic ylides with phenyl groups at the phosphorus atom with trithianes (R2MS)3 (M = Ge, Sn) occurs slowly and is impeded by several side processes. 

Modelli and coworkers126 studied by PES and ETS (electron transmission spectroscopy) some silicon and tin derivatives of thiophene and furan, with the aim of following the energy gap between the HOMO and the LUMO as a function of the substituents. In particular they investigated the following tin derivatives ... 

This direct electrochemical synthesis has proved efficient in the preparation of several other complexes, among these the tin derivatives of 3-hydroxy-2-phenylflavone (2) and 2-ethoxyphenol (3), respectively. The use of sacrificial electrodes proved very efficient the produced complex precipitates during electrolysis and is easy to isolate135. 

These workers have also used 3-iodopyrrole 103 to prepare the corresponding tin derivative 104 for Stille couplings to furnish 3-arylpyrroles 105 [78], These pyrrole derivatives are important for the synthesis of (i-aryl-substituted porphyrins for studies of heme catabolism. Also synthesized in this study were compounds 106 and 107 [78]. 

In addition, due to the proximity and inductive effect of the indoline nitrogen, a metalation strategy provides for a facile synthesis of 7-bromoindoline, as well as other 7-substituted indolines. Thus, Iwao and Kuraishi find that IV-Boc-indoline (22) is smoothly lithiated at C-7 to give 7-lithio 23. Quenching 23 with suitable electrophiles gives 7-haloindolines 24-26, and quenching with tri-n-butylstannyl chloride affords the corresponding tin derivative in 65% yield [31]. 

The color of the final product primarily depends on the qualification of the raw materials, TPA, DMT and EG. The content of heavy metals in TPA, residues of catalysts employed during oxidation of p-xylene, and polymer processing affect the final color of the polymer. The tendency of certain catalysts, such as titanium or tin derivatives, to make the polyester yellowish in color is well established. The conversion during esterification is prolonged due to larger TPA particles or their hardness. Color can be influenced by these factors, as well as by chemical impurities in the raw materials, such as water, aldehydes or the quality of insufficiently recovered EG. Similar effects on color can be observed as a result of impurities caused by additives, particularly from less purified Sb2C>3. The quality of the latter can be assessed simply by the color of its solution in EG. 

Mineral fillers and additives aluminium trihydrate (ATH), magnesium hydroxide and boron derivates are the best known but tin derivates, ammonium salts, molybdenum derivates and magnesium sulphate heptahydrate are used to varying extents and nanofillers are developing. 

A range of examples of alkylation reactions via radicals generated through electron transfer sensitization is available in the literature, and a few of them are reported in Figure 3.12. Alkyl tin derivatives can be used as precursors, but in many cases these highly toxic reagents can be advantageously substituted by... 

Fig. 2.20. Reaction of heteroatom-substituted carbene complexes with nucleophilic and electrophilic tin derivatives.

Naphthalene-based bifunctional Lewis acids that involve boron and a heavier group 13 element have also been prepared starting from the boron/tin derivative 30 (Scheme 15). Thus, the transmetalation reaction of 30 with gallium trichloride or indium trichloride in tetrahydrofuran (THF) results in high yields of l-(dichlorogallium)-8-(dimesitylboron)naphthalenediyl 35 and l-(dichloroindium)-8-(dimesitylboron)... 

The fact that the silyl and germyl compounds have IHI, whereas the tin derivatives do not, seems surprising, considering the greater tendency of heavier main group elements to form hypervalent structures. This discrepancy can be explained considering the mechanism of IHI. Because IHI stems from the electron... 

Very efficient cross coupling reactions of tin derivatives with [4- F]fluorobro-mo and [4- F]fluoroiodobenzenes have been carried out [162, 163] (Scheme 42). Reaction of the appropriate piperazine with [4- F]fluorobro-mobenzene under Hartwig-Buchwald conditions [187] yields [ F]RP 62203 in high specific activity and biologically usable amounts. This method appears superior to the one described previously starting from [ F]fluoronitrobenzene (Scheme 18). 

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