Tin-carbon Bond Research Articles

Palladium-iminophosphine-catalysed carbostannylation of arynes: synthesis of ortho-substituted arylstannanes.

Arynes were found to insert into a carbon-tin bond of alkynyl- and vinylstannanes in the presence of a catalytic amount of a palladium-iminophosphine complex to afford ortho-substituted arylstannanes, which were convertible into a wide variety of 1,2-disubstituted arenes via carbon-carbon bond forming reactions.

Selective tin-carbon bond cleavage reactions of trimethylstannylzirconocene dichloride with electrophiles.

The reaction of 5,5-bis(trimethylstannyl)cyclopentadiene with CpZrCl3 (Cp = eta 5-C5H5) affords the monostannylated metallocene complex (eta 5-Me3SnC5H4)CpZrCl2 (1), accompanied by variable amounts of (eta 5-ClMe2SnC5H4)CpZrCl2 (2). The complex (1) reacts with BCl3 or with ICl to afford 2 (Sn-CH3 cleavage), but with HCl, Cp2ZrCl2 is obtained instead (Sn-Cp cleavage). Depending on the reaction conditions, treatment of either 1 or 2 with BBr3 affords (eta 5-BrMe2SnC5H4)CpZrBr2 (3) or (eta 5-Br2MeSnC5H4)CpZrBr2 (4). The reaction of 1 with excess I2 affords the iodostannylated complex (eta 5-IMe2SnC5H4)CpZrCl2 (5). Two of the complexes (2.2C6H5CH3 and 4.THF) are crystallographically characterized. The adduct 4.THF has a distorted trigonal bipyramidal geometry about tin with a long O-Sn distance of 2.655 A. We find overall that Me3Sn substituents undergo electrophilic halodemethylation much more readily than corresponding Me3Si substituents, whereas the reactivities of the halostannylated complexes toward nucleophiles such as airborne moisture are much lower than those of their halosilylated counterparts.

Synthesis and reactivity of conformationally locked alpha-aminoorganostannanes and alpha-aminoorganolithiums. Discovery of a surprising configurational requirement for transmetalation.

[equation--see text] 2-Tributylstannyl-N-methylpiperidines that are conformationally locked by a 4-tert-butyl substituent were evaluated in transmetalations (Sn-Li exchange) and reactions with electrophiles. When the tin is equatorial, transmetalation occurs smoothly as does reaction with carbonyl electrophiles. Alkyl halides seem to undergo single electron transfer reactions, affording nonselective alkylation products, along with products of radical disproportionation. In a surprise, an axially oriented tin failed to transmetalate, suggesting that a synclinal relationship between the nitrogen lone pair and the carbon-tin bond is a requirement for transmetalation.

Preparation of methylcyclopentane-1-d1

The title compound has been prepared in 70% yield by the reaction between 1-chloro-1-methylcyclopentane and deuterotributylstannane, without solvent. Small amounts (0.7–3.5%) of unreacted starting material remained after the reaction and were removed by solvolytic HCl elimination with water or aqueous sodium hydroxide, followed by oxidation with potassium permanganate or bromine addition at low temperature, which form products of low volatility. Small amounts of a by-product, deuterobutane, resulting from the cleavage of the carbon-tin bond in the reactant were also observed in the product. Copyright © 2000 John Wiley & Sons, Ltd.

デオキシスタニル化によるオレフィン形成反応

Radical hydrostannylation of propargylic alcohols gives stannylated allylic alcohols regio- and stereoselectively, and subsequent β-elimination of stannyl alcohols (deoxystannylation) gives allenes in a one-pot process. Deoxystannylation proceeds in an anti-fashion by treatment with methanesulfonyl chloride and triethylamine at or below room temperature. Epoxidation or cyclopropanation of a chiral stannylated allylic alcohol and subsequent deoxystannylation affords a chiral allene oxide or alkylidenecyclopropane, respectively. A chiral allene oxide is isolated and characterized for the first time. [3] Cumulenes are synthesized from propargylic alcohols by the stannylation-deoxystannylation sequence. 1, 4-Elimination of stannylated propargylic alcohols as well as 1, 2-elimination of stannylated allenyl alcohols proceeds effectively to give [3] cumulenes. Deoxystannylation proves to be much more efficient than an analogous silyl counterpart because a vinylic carbon-tin bond is easily cleaved under mild reaction conditions.

Palladium-Catalyzed Cross-Coupling Reaction of Tributyltin Hydride with Aryl Iodides: Formation of A Tin-Carbon Bond

Palladium-Catalyzed Cross-Coupling Reaction of Tributyltin Hydride with Aryl Iodides: Formation of A Tin-Carbon Bond

Synthesis of Boron-Halogenated Diborylamines and Diborylhydrazines by Cleavage of Stannazanes

The diborylamines R′–N(BRX)2 (3; × = Cl, Br) are obtained by stannazane cleavage of distannylorganylamines R′–N(SnMe3)2 (4) with alkyldihaloboranes RBX2 in a 1:2 molar ratio. The presence of the sterically demanding substituents R and R′ also causes carbon–tin bond cleavage, resulting in low yields of 3. However, carbon–tin bond cleavage can be suppressed by the use of bis(dimethylchlorostannyl)organylamines 5 as the nitrogen source for the synthesis of diborylamines. This results in almost quantitative yields of the compounds 3. Treatment of the distannylhydrazines R2N–N(SnMe3)2 (7) with RBX2 in a 1:2 molar ratio leads to the formation of N,N-bis(alkylhaloboryl)hydrazines 8 under mild conditions and in good yield. The molecular structures of 3 and 8 were determined by multinuclear magnetic resonance spectra in solution as well as by X-ray structure analysis in the case of 8d. A typical structural feature of 8d is the intramolecular BN adduct formation. Support for the constitutions of compounds 8c comes from MS fragmentation patterns as well as from IR spectra.

Synthesis of Boron-Halogenated Diborylamines and Diborylhydrazines by Cleavage of Stannazanes

The diborylamines R′–N(BRX)2 (3; × = Cl, Br) are obtained by stannazane cleavage of distannylorganylamines R′–N(SnMe3)2 (4) with alkyldihaloboranes RBX2 in a 1:2 molar ratio. The presence of the sterically demanding substituents R and R′ also causes carbon–tin bond cleavage, resulting in low yields of 3. However, carbon–tin bond cleavage can be suppressed by the use of bis(dimethylchlorostannyl)organylamines 5 as the nitrogen source for the synthesis of diborylamines. This results in almost quantitative yields of the compounds 3. Treatment of the distannylhydrazines R2N–N(SnMe3)2 (7) with RBX2 in a 1:2 molar ratio leads to the formation of N,N-bis(alkylhaloboryl)hydrazines 8 under mild conditions and in good yield. The molecular structures of 3 and 8 were determined by multinuclear magnetic resonance spectra in solution as well as by X-ray structure analysis in the case of 8d. A typical structural feature of 8d is the intramolecular BN adduct formation. Support for the constitutions of compounds 8c comes from MS fragmentation patterns as well as from IR spectra.

Cleavage Oftin-Aryl Bond(S) by Monohalocarboxylic Acids: The Steric Factor Role

All four tin-carbon bonds of tetra-p-tolyltin can be successively cleaved by iodoacetic acid. Reactions with tetra-m-tolyltin are sluggish and only one tin-carbon bond is cleaved, even in the presence of an excess of the acid. Tetra-o-tolyltin does not react under similar conditions. Stene factors arc thought to be responsible for this difference in reactivity of tetratolyltins. The monocarboxylates were not isolated in case of Ph4Sn (except with CCl3COOH). Tetraphenylgermanium gives only the monocarboxylates Ph3GeOOCR', (R = CH2CI, CH2Br, CH2I), but all the Ph-Pb bonds in tetraphenyllead may be successively cleaved. Tri-p-tolyltin chloride reacts with iodoacetic acid to give a mixed chloro halocarboxylate, (p-MeC6H4)2SnC1(OOCCH2I), but attempts to prepare a mixed carboxylate by reacting (p-MeC6H4)3SnOOCCH2CI with HOOCCH2I failed.

Novel Organoaluminum Lewis Acids via Selective Aluminum-Tin Exchange Processes – Electrophilic Initiation by the Aluminum Halide and Ensuing Complexation by the Resulting Tin Halide

With the goals of preparing novel carbaluminating reagents and mono- and bidentate organoaluminum Lewis acids, the scope and limitations of synthesizing the requisite organoalanes by the aluminum-tin exchange between an aluminum halide and the appropriate organostannane have been examined in detail. The interactions of such tin precursors as 1,2-bis(trimethylstannyl)ethyne, allyltri-n-butyltin, benzyltrimethyltin, and 1,2-bis(trimethylstannyl)benzene and various aluminum chlorides of the type, RnAlCl3–n (R = Me, Et), gave selective aluminum-tin exchange at the sp- or sp2-hybridized carbon–tin bond and produced such organoalanes as allyl(methyl)aluminum chloride, benzylaluminum dichloride, 1,2-bis(diethylalumino)ethyne, 1,2-bis(dimethylalumino)benzene, 1,2-bis[chloro(methyl)alumino]benzene, and 1,2-bis(dichloroalumino)benzene in high yield. A complicating factor was the tendency of the R3SnCl by-product to complex with the resulting organoalane. In some cases, exemplified by allyl(methyl)aluminum chloride, such complexation did not interfere with the carbaluminating action of the reagent; in other cases, exemplified by 1,2-bis[chloro(methyl)alumino]benzene, the R3SnCl could be removed by means of π-bases and reduced pressures; and in still other structures, as with 1,2-bis(dichloroalumino)benzene, the tin chloride could not be dislodged at moderate temperatures. The structure and bonding in such tin halide–aluminum halide complexes in solution were investigated with the 1:1 adducts of AlCl3 with Me3SnCl and with nBu3SnCl, respectively, by means of multinuclear NMR spectroscopy. Furthermore, an XRD of the solid complex, Me3SnCl · AlCl3, was carried out. Such complexes were shown to consist of 1:1 ion pairs of the type [R3Sn+][AlCl4−] in dilute solution and of a chiral polymeric helix in the solid state wherein planar Me3Sn+ units are linked to each other via bridging tetrachloroaluminate anions, Cl–(AlCl2)–Cl−. Treatment of such complexes with either benzyltriethylammonium chloride (one or two equivalents) or tetramethylphosphonium chloride leads to the displacement of Me3SnCl and the formation of the expected ionic complexes. Finally, the importance of such novel reagents and chelating Lewis acids to organic synthesis and olefin polymerization is discussed and elucidated.

Novel Organoborane Lewis Acids via Selective Boron-Tin Exchange Processes Steric Constraints to Electrophilic Initiation by the Boron Halide

With the purpose of preparing novel mono- and bidentate organoboron Lewis acids, the scope and limitations of synthesizing the requisite organoboranes by the boron-tin exchange between a boron halide and the appropriate organostannane have been examined in detail. The following organotin derivatives have been obtained either from the corresponding RMgBr or RLi reagent and MenSnCl4–n or from a Barbier procedure using the organic halide, Me3SnCl and magnesium metal: 1,2-bis(trimethylstannyl)ethyne, o-, m-, and p-bis(trimethyl-stannyl)benzenes, α,o-bis(trimethylstannyl)toluene, α,α-bis(trimethylstannyl)-o-xylene, and 2,2-dimethyl-2-stannaindane. The individual interaction of the 1,2-bis(trimethylstannyl)ethyne and the isomeric bis(trimethylstannyl)benzenes with Et2BBr produced the corresponding bis(diethylboryl)-derivatives. By contrast, with Et2BCl the α,o-bis(trimethylstannyl)toluene gave only o-diethylboryl-α-trimethylstannyltoluene and with BCl3 the α,α′-bis(trimethylstannyl)-o-xylene formed only,-bis-(chlorodimethylstannyl)-o-xylene. Furthermore, in the attempted double boron-tin exchange between o-bis(trimethylstannyl)benzene and BCl3, an unprecedented rearrangement of the 1-(dichloroboryl)-2-(trimethylstan-nyl)benzene intermediate into its 1-[chloro(methyl)boryl]-2-(chlorodimethylstannyl) isomer was observed. Likewise, o-bis(trimethylstannyl)benzene with PhBCl2 produced by a similar rearrangement 1-[methyl(phenyl)boryl]-2-(chloro-dimethylstannyl)benzene. The thermolysis of such boranes led variously to definite dimers or ill-defined oligomers. Preliminary studies of the properties of these organoboranes have identified the heightened Lewis acidity of 1,2-bis(diethylboryl)ethyne and the π-electron delocalization involving the 2pz-boron orbitals in the 9,10-dihydro-9,10-diboraanthracene system. Finally, an electronic mechanism for the boron-tin exchange has been developed to account for the selectivity of the boron halide's attack at unsaturated carbon–tin bonds.

Formation of a Pentacoordinate 1,2-Oxastannetanide by Novel Base-Induced Rearrangement of a Bis(β-Hydroxyalkyl)Stannane

Treatment of a bis(β-hydroxyalkyl)diphenylstannane with potassium hydride in THF in the presence of 18-crown-6 gave the corresponding pentacoordinate t-alkoxy-l,2-oxastannetanide as stable crystals instead of a hexacoordinate stannate with two oxetane rings. This compound is considered to be formed by novel tin-1,3-migration reaction from carbon to oxygen reaction involving the formation of an oxetane ring and the subsequent tin-carbon bond cleavage.

Tin for organic synthesis. Part 15: The use of 1,2-bis(trimethylstannyl) -1-alkenes in electrophilic destannylation reactions

Z-1,2-Bis(trimethylstannyl)-1-alkenes show different types of reaction behaviour towards various electrophiles. p-Tolysulphonyliso-cyanate forms five-membered tin-nitrogen-containing heterocycles. 1,1-Dichloromethylmethyl ether reacts with carbofunctionalised distannylalkenes to yield α,β-unsaturated aldehydes, which are useful tools for the synthesis of further substituted vinylstannanes. Z-1,2-Bis(trimethylstannyl)- 1-alkenes containing heteroatoms such as O or N undergo only protodestannylation with this electrophile. The reaction of Z-1,2-bis (trimethylstannyl)-1-alkenes with trimethylsilyl chlorosulphonate followed by hydrolysis with aqueous NaHCO 3 provides the corresponding sodium sulphonates. SO 2 and SO 3 undergo insertion into both tin-carbon bonds in an ipso- and stereospecific manner to form bis-sulphinic- or bis-sulphonic bis(trialkylstannyl) esters.

Tin–carbon bond formation by simple addition of cyclic dienes to a bis(amino)stannylene: a mechanistic study

The addition of cyclopentadiene and indene to But[graphic omitted]n resulted in the formation of ‘adducts’(X-ray structural characterisation) through tin-carbon bonding and hydrogen migration to one of the nitrogen atoms. In the cyclopentadienyl compound π bonding is observed (Sn–C 2.47–2.76 A) whereas the indenyl derivative displays a σ-bond (Sn–C 2.343 A). In a similar reaction of But[graphic omitted] (E = Ge or Pb) with cyclopentadiene either the starting compounds or plumbocene along with an amine were isolated. At room temperature the reaction between indene and the cyclic stannylene is an equilibrium, the rate constants of which were raised by a factor of 3.0 for the association and slowed by a factor of 4.2 for the dissociation when deuteriated indene was used. From the kinetic data, a concerted addition mechanism of the proton and the indenyl group is favoured over an ionic two-step mechanism. If the steric hindrance of the protic cyclic diene system is raised (pentamethylcyclopentadiene) no reaction between the stannylene and diene is observed.

Synthesis, stability, and reactions of 10-Sn-5 tin ate complexes bearing four tin-carbon bonds

The monocyclic organostannates ( o- C 6H 4C(CF) 3) 2O)SnR 2(p-CH 3C 6H 4) −Li +( 2a−Li +(R = Me), 2b−1Li + (R = tBu) ) bearing four SnC bonds, which can be prepared from the reaction of tetracoordinate tin 3a (R = Me and 3b ( R = tBu ) with p-CH 3C 6H 4Li, were found to be thermally stable but were unstable to moisture giving 3 quantitatively upon aqueous workup. These ate complexes were inert toward some typical electrophiles such as p-methoxybenzaldehyde, but were reactive enough toward 1,3-bis(methoxycarbonyl)pyridinium chloride ( 8) to give corresponding alkylated(arylated) dihydropyridines ( 9). These are quite unique examples in the respect that organostannanes bearing four SnC bonds, which have been known to be reluctant to form compounds of higher coordination numbers, formed stable pentacoordinate ate complexes and showed unique reactivity which differed from that of lithium reagents such as p-CH 3C 6H 4Li which could have formed upon dissociation from the ate complexes. The reaction of 3a with nBuLi gave complex mixtures after treatment with water indicating that the expected ate complexes (o- C 6H 4C(CF 3) 2O)SnMe 2 ( nBu) −Ki +( 2c−Li + ) was thermally unstable and existed in an equilibrium with a ring-opened structure 5c.

Stereoselective and Convenient Synthesis of Diethyl (E)-α-Triphenylstannyl or (Z)-α-Tributylstannyl α-Alkenylphosphonates

Abstract Diethyl (E)-α-triphenylstannyl or (Z)-α-tri-n-butylstannyl α-alkenylphosphonates are conveniently and stereoselectively prepared using a “tin-Peterson-like” reaction. Protonolysis of the carbon-tin bond of α-tributylstannyl derivatives proved to be easy and stereospecific.

Dynamic-Mechanical Properties of Tin-Coupled SBRs

Abstract The interaction between rubber and carbon black in compounds for road tire treads has been analyzed by using mechanical and dynamical measurements in three cured compounds based on SBRs. The rubbers were prepared in solution by anionic polymerization, and coupled with tin compounds in which the carbon-tin bond at the end of the chain may correspond to styryl or butadienyl terminations. The interaction parameter, defined by the ratio of mechanical and dynamic terms, has been used for the first time for the evaluation of the compounds. The SBRs with tin-butadienyl bonds exhibit an improved interaction with the filler, with increasing tin content.

The synthesis and ir and NMR ( 1HH, 3CC AND 9Sn)Sn) spectral studies of some methyltin(IV) sulphonates

Some methyltin(IV) sulphonates, Me nSn(OSO 2X) 4‒ n ( n = 1−3 and X = 4-tolyl and 2-naphthyl) have been prepared. The 1H, 3C and 9Sn NMR spectra of these compounds and the previously reported compounds, Me 3Sn(OSO 2X) (X = CF 3, CH 3 and 4-CH 3 C 6H 4) and Me 2Sn(OSO 2CH 3) 2, in coordinating and non-coordinating solvents have been studied. From the chemical shifts δ( 9Sn) and the coupling constants 1 J( 13C, 119Sn) and 2 J( 1H, 119Sn), coordination number of the tin atom and the geometry of its coordination sphere have been suggested. These observations have been complemented by IR spectroscopy. Synthesis of the ternary compounds, MeSnCl(OSO 2X) 2 (X = CH 3 and 4-CH 3C 6H 4), by reaction between Me 3Sn(OSO 2X) and Me 2SnCl 2 and subsequent cleavage of the tin-carbon bond is also discussed.

The gas phase thermolysis and oxidative thermolysis of some homoleptic tetraalkylstannanes: An FT-IR study

Fourier transform infared spectroscopy has been employed to investigate the thermal decomposition chemistry of a number of homoleptic tetraorganostanannes, R 4Sn(REt, nPr, iPr, nBu, sBu) in the temperature range 543–573 K. Neat tetraethyltin and tetra- n-butyltin give principally alkene (ethene when R Et; a mixture of but-1-ene and cis- and trans-but-2-ene when R nBu) with some of the corresponding alkane. When the thermolysis reactions are carried out in the presence of oxygen decomposition of all the tetraalkylstannanes studied give alkene and an organic carbonyl compound, together with carbon dioxide and water. In the cases of tetra- n-propylin, tetra- iso-propyltin and tetra- sec-butylin, propanal, acetone, and butanone, respectively, are formed as the tetraorganotin is consumed. Only small amounts of carbonyl compounds are formed initially in the thermal decomposition of tetraethylin and tetra- n-butylin in the presence of oxygen, alkenes being the major product, although in the latter case peaks due to butyraldehyde grow in intensity as the reaction mixture is held at 573 K. The decompositions in both the absence and presence of oxygen are considered to proceed by radical mechanisms involving the homolytic fission of the tin-carbon bond to produce alkyl radicals, which react to give the observed products.

Cleavage of Tin-Carbon Bonds of Organosilylstannane and Organodistannane in Photo-Induced Electron Transfer Reactions and Mass Spectrometry

Abstract Photoalkylation of tetracyanobenzene and benzil with (n-Bu)3SnSiMe3 or (n-Bu)3SnSn(n-Bu)3 proceeds via electron transfer. In these reactions, the Sn–C bond of (n-Bu)3SnSiMe3 and (n-Bu)3SnSn(n-Bu)3 is cleaved in preference to the Sn–Si and Sn–Sn bonds. Similar cleavage of the Sn–C bond is also observed in mass spectra of these group 14 organometallic compounds.