- Highly stereoselective addition to alkoxy or hydroxy ketones using an α-stannyl ester-stannous chloride system in a chelation-controlled manner
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The reaction of an α-stannyl ester with α-alkoxy or hydroxy ketones in the presence of SnCl2 gave aldol-type products with high selectivity in a chelation-controlled manner.
- Yasuda,Okamoto,Sako,Baba
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- INVESTIGATION OF THE DIRECT SYNTHESIS OF TETRABUTYLTIN FROM BUTYL CHLORIDE
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The direct synthesis of tetrabutyltin from butyl chloride, has been investigated, and the various contributing reactions have been identified.A mechanism is proposed for the overall synthesis, which comprises radical-ionic processes for the liberation of metal atoms from the surfaces of the metal powders, followed by formation of bridging intermediates leading to the transfer of butyl groups from zinc to tin, until the synthesis of tetrabutyltin is complete.Although dibutyltin dihalides were shown to be probable intermediates in the process, the known organohalostannate complex Bu4N+ - was not found to be formed under the conditions used.
- Nicholson, John W.,Douek, Josephine A.,Collins, John D.
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- Preparation and characterization of dimethoxyphosphine
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Dimelhoxyphosphine, (CH3O)2PH, has been obtained from the reaction of PF2H, CH3OH, and pyridine and from the carefully controlled reduction of (CH3O)2PCl by (C4H9)3SnH
- Centofanti
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- A highly selective synthesis of R2SnX2 (R = alkyl, X = Br, Cl) species directly from tin and alkyl halides
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The reaction : Sn + 2RX -> SnR2X2 (X = Cl, Br) occurs at relatively low temperature (80 - 120 degC) and with selectives as high as 95 - 99percent in the presence of catalytic system fored by a crown ether and potassium iodide.The reaction is favoured by aprotic dipolar solvents such as dimethylformamide; the presence of an alkyl iodide as cocatalyst has a positive effect, the selectivity remaining unchanged.
- Ugo, R.,Chiesa, A.,Fusi, A.
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- Use of the extended one-pot (EOP) procedure for the preparation of ethynylated thiophene derivatives and related palladium-ethynylthiophene organometallic oligomers
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The palladium-catalyzed coupling (Stille coupling) of 2,5-diiodothiophene (1) with tributyl(ethynyl)tin forms the 2,5-bis(ethynyl)thiophene (3) and tributyltin iodide as side product (step 1). Addition of lithium diisopropylamide (LDA) to this mixture causes deprotonation of the bis-alkyne and its reaction with the tin halide present in the medium to form the 2,5-bis[(tributyltin)ethynyl]thiophene (4) (step 2). To this mixture was subsequently added trans-dichlorobis(tri-n-butylphosphine)palladium (5), and the corresponding trans-bis(tri-n-butylphosphine)-μ-[2,5-bis(ethynyl)thiophene]palladium oligomer (6) was obtained (step 3). Alternatively, the same route can be directed toward the formation of ethynylated thiophene oligomers: after formation of the 2,5-bis[(tributyltin)ethynyl]thiophene (4) (step 2), addition of 2-iodothiophene (8) or 2-iodo-5-(trimethylsilyl)thiophene (10) led to the formation of 2,5-bis(2-thienylethynyl)thiophene (9) (step 3) and [2-trimethylsilyl(ethynyl)thiophene]-2,5-bisethynylthiophene (11) (step 3′), respectively. The latter can be easily desilylated to obtain the [2-(ethynyl)thiophene]-2,5-bisethynylthiophene (13), while treatment of 9 with sec-BuLi/I2 formed the 2,5-[2,2′-(5,5′-diiodo)bisthienyl]bisethynylthiophene (12). Through a sequence of transformations similar to steps 1-3, the oligo(iodo)ethynylthiophene 12 has been connected to the bis(tri-n-butylphosphine)palladium moiety to form the trans-bis(tri-n-butylphosphine)-μ-[2,2′-bis(ethynyl)thiophene]-2,5-bise thynylthiophene]palladium polymer (15). To compare the advantages of the above extended one-pot (EOP) procedures over classical routes, polymers 6 and 15 were also prepared by the copper-catalyzed reaction of trans-dichlorobis(tri-n-butylphosphine)palladium (5) with 2,5-bis(ethynyl)thiophene (3) and [2-(ethynyl)thiophene]-2,5-bisethynylthiophene (13).
- Altamura, Patrizia,Giardina, Giorgio,Sterzo, Claudio Lo,Russo, Maria Vittoria
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- Isocyanide insertion across the Pd-C bond of allenyl and propargyl palladium complexes bearing phosphoquinoline as a spectator ligand. Synthesis of a palladium complex bearing a coordinated cyclobutenyl fragment
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We have studied the insertion of p-toluenesulfonylmethyl isocyanide (TosMIC) on selected allenyl and propargyl complexes of palladium bearing diphenylphosphine quinoline as a spectator ligand. The fast process gives different products depending on the tautomer involved in the reaction. Thus, the unsubstituted allenyl species yields an insertion complex with the isocyanide coordinated between the metal and the first allenyl carbon. On the other hand, a mixture of phenyl substituted allenyl and propargyl palladium complexes yields a novel species characterized by a cyclo-butenyl fragment directly coordinated to palladium. The solid state structure of such a complex together with an exhaustive kinetic study of the whole process is reported.
- Scattolin, Thomas,Visentin, Fabiano,Santo, Claudio,Bertolasi, Valerio,Canovese, Luciano
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- Synthesis of monophosphines directly from white phosphorus
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Monophosphorus compounds are of enormous industrial importance due to the crucial roles they play in applications such as pharmaceuticals, photoinitiators and ligands for catalysis, among many others. White phosphorus (P4) is the key starting material for the preparation of all such chemicals. However, current production depends on indirect and inefficient, multi-step procedures. Here, we report a simple, effective ‘one-pot’ synthesis of a wide range of organic and inorganic monophosphorus species directly from P4. Reduction of P4 using tri-n-butyltin hydride and subsequent treatment with various electrophiles affords compounds that are of key importance for the chemical industry, and it requires only mild conditions and inexpensive, easily handled reagents. Crucially, we also demonstrate facile and efficient recycling and ultimately catalytic use of the tributyltin reagent, thereby avoiding the formation of substantial Sn-containing waste. Accessible, industrially relevant products include the fumigant PH3, the reducing agent hypophosphorous acid and the flame-retardant precursor tetrakis(hydroxymethyl)phosphonium chloride. [Figure not available: see fulltext.]
- Scott, Daniel J.,Cammarata, Jose,Schimpf, Maximilian,Wolf, Robert
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p. 458 - 464
(2021/04/09)
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- Organic tin compound cycle application Stille method of synthesis of biphenyl
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The invention provides a method for synthesizing diphenyl through Stille reaction recycling with an organotin compound, and relates to a method for preparing diphenyl through a Stille reaction. A purpose of the present invention is to solve the problem of low organotin utilization rate of the existing Stille method for preparing the diphenyl compound. The method comprises: 1, adopting tri-butyltin chloride and bromobenzene as raw materials, and carrying out a reaction under the effect of a Grignard reagent to synthesize tributylphenyltin; 2, carrying out a reaction of a mixed solution of halogenated benzene, tributylphenyltin, cuprous iodide, lithium chloride, palladium(triphenylphosphine)dichloride and cesium fluoride DMF to prepare diphenyl, and collecting the filter residue; 3, dissolving the filter residue with acetone, dissolving the insoluble matter with absolute alcohol, and concentrating to obtain fluorotributyltin; and 4, converting the tin fluoride into the organic tin chloride with saturated ammonium chloride tetrahydrofuran. According to the present invention, the synthesis process conditions are optimized, the highest yield of the diphenyl compound achieves 97%, and the effective separation utilization of the organic tin chloride is achieved.
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Paragraph 0051; 0055
(2017/05/12)
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- Reductive dechlorination of BCl3 for efficient ammonia borane regeneration
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This paper reports a complete ammonia borane (AB) regeneration process in which Bu3SnH was utilized as a reductant for the reductive dechlorination of BCl3, and Et2PhN was selected as a 'helper ligand' to generate Et2PhN·BH3, which gives rise to a high yield of AB by a base-exchange reaction at ambient temperature.
- Tan, Yingbin,Zhang, Lijun,Chen, Xiaowei,Yu, Xuebin
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supporting information
p. 753 - 757
(2015/02/19)
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- Green synthetic approach to 5-substituted-1h-tetrazoles via recycle and reuse of tributyltin chloride
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A simple, safe and efficient process for the recycle of tributyltin chloride from tributyltin hydroxide is developed and its reuse in the synthesis of 5-substituted-1H-tetrazoles is successfully demonstrated, which paved a way to reduce the toxic tin waste significantly. Recycling of tributyltin chloride is possible over six cycles without loss of its activity.
- Sampath,Reddy, V. Prabhakar,Chakravarthy, A. Kalyan,Reddy, P. Pratap
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p. 393 - 396
(2013/02/22)
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- Indium-mediated regioselective synthesis of ketones from arylstannanes under solvent-free ultrasound irradiation
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The solvent-free indium-promoted reaction of alkanoyl chlorides with sterically and electronically diverse arylstannanes is a simple and direct method for the regioselective synthesis of primary, secondary and tertiary alkyl aryl ketones in good to excellent isolated yields (42-84%) under mild and neutral conditions. The protocol is also adequate for the synthesis of aryl vinyl ketones. Reaction times are drastically reduced (from 3-32 h to 10-70 min) under ultrasonic irradiation. Evidences for the involvement of a homolytic aromatic ipso-substitution mechanism, in which indium metal acts as radical initiator, are presented. It is possible the transference of two aryl groups from tin, thus improving effective mass yield, working with diarylstannanes as starting substrates.
- Lo Fiego, Marcos J.,Badajoz, Mercedes A.,Domini, Claudia,Chopa, Alicia B.,Lockhart, María T.
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p. 826 - 832
(2013/03/14)
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- Recycling of organotin compounds
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A method for the synthesis of a first organic molecule, said method comprising the steps of: a) Reacting a first reactant with an organotin reactant having at least one organic group having from 5 to 20 carbon atoms selected from alkyl, alkoxyalkyl, alkoxy, alkylthioalkyl, carboxylates and alkylaminoalkyl groups, thereby forming a mixture of a product and a tin-containing by-product, and b) Removing most of the tin-containing by-product from said mixture in such a way as to provide a purified product comprising less than 1000 ppm of remaining tin-containing by-product, wherein said step of removing most of said tin-containing by-product is either an extraction between a first liquid being an alkane or a mixture of alkanes having from 5 to 17 carbon atoms and a second liquid more polar than said first liquid or is a reversed phase chromatography.
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Paragraph 0102
(2013/12/02)
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- Transfer of organic groups to gold using organotin compounds
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PhSnMe3 undergoes transmetallation with [AuCl(EPh3)] (E = P, As) in refluxing toluene forming [AuPh(EPh3)] and Me 3SnCl. The analogous nBu derivative does not transmetallate, even under forcing conditions. Similarly, 1-(trimethylstannyl) naphthalene and 1-(trimethylstannyl)-8-iodonaphthalene react with [AuCl(PPh 3)] to give good yields of the corresponding naphthylgold(I) complexes which were spectroscopically and structurally characterised.
- Meyer, Nadine,Sivanathan, Sivatharushan,Mohr, Fabian
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p. 1244 - 1247
(2011/04/22)
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- Recycle of tin thiolate compounds relevant to ammonia-borane regeneration
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The use of benzenedithiol as a digestant for ammonia-borane spent fuel has been shown to result in tin thiolate compounds which we demonstrate can be recycled, yielding Bu3SnH and ortho-benzenedithiol for reintroduction to the ammonia-borane regeneration scheme.
- Sutton, Andrew D.,Davis, Benjamin L.,Bhattacharyya, Koyel X.,Ellis, Bobby D.,Gordon, John C.,Power, Philip P.
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p. 148 - 149
(2010/04/01)
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- PROCESS FOR PRODUCTION OF DIALKYLTIN DIALKOXIDES
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An object of the present invention is to provide a process for producing a dialkyl tin compound from a composition of deactivated forms of a dialkyl tin catalyst, and to provide a process for producing the dialkyl tin catalyst from the dialkyl tin compound and using the dialkyl tin catalyst to produce a carbonic acid ester. According to the present invention, a process for producing a dialkyl tin compound is provided that subjects a composition of the deactivated forms of the dialkyl tin catalyst, formed when producing an ester compound, to an alkyl group redistribution reaction and/or dealkylation reaction.
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Page/Page column 35-36
(2009/07/25)
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- Di(phosphavinyl) ethers (2,4-diphospha-3-oxapentadienes)
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Hydrolytic cleavage of the P-chlorophosphaalkenes (RMe2Si) 2C=PCl (R = Me: 1a; R = iPr: 1b) in the presence of triethylamine leads to di(phosphavinyl) ethers (2,4-diphospha-3-oxapentadienes) [(RMe 2Si)2C=P]2O (2a, 2b) as main products, accompanied by alkylphosphinic acids (RMe2Si)2(H)CP(H)(O) OH (3a, 3b). The hydrolysis of (PhMe2Si)2C=PCl (1c) proceeds less selectively. Reactions with metal oxides under aprotic conditions provide 2a [impure, from 1a with (nBu3Sn)2O] and 2b [from iodophosphaalkene (iPrMe2Si)2C=PI with Ag2O] as oils. 1H, 13C, 29Si and 31P NMR spectra, however, allow unambiguous characterisation of 2a and 2b. Formation mechanisms, structure, and C=P-O π stabilisation of the oxabisphosphaalkene [(H3Si)2C=P]2O (2′) were studied with DFT methods. The double [2+4] cycloaddition reaction of 2a with two equivalents of cyclopentadiene leads to the phosphinous anhydride 7 as a mixture of diastereomers whereas the addition of two equivalents of tetrachloro-o- benzoquinone proceeds in a diastereoselective fashion. An X-ray crystal structure determination of the resulting oxo-bridged bis(2-phospha-2,5-dioxa-3, 4-benzophospholene) derivative 8 revealed the presence of a racemic mixture of (R,R)- and (S,S)-configurated molecules. The solid state structure of a by-product, bisylphosphonic tetrachlorocatechol monoester (Me 3Si)2CH-P(=O)(OH)-o-OC6Cl4OH 9, was also determined crystallographically.
- Birzoi, Roxana M.,Bugnariu, Delia,Goers, Christine,Gimeno, Rafael Guerrero,Gust, Thorsten,Riecke, Antje,Benko, Zoltan,Koenczoel, Laszlo,Nyulaszi, Laszlo,Wismach, Cathleen,Jones, Peter G.,Schmutzler, Reinhard,Bartsch, Rainer,Du Mont, Wolf-W.
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- Platinum-catalyzed phenyl and methyl group transfer from tin to iridium: Evidence for an autocatalytic reaction pathway with an unusual preference for methyl transfer
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Platinum complexes have been found to catalyze the transfer of σ-bound ligands to the Ir center in Cp*(PMe3)IrCl2 (Cp* = η5-C5Me5) from Bu3SnPh and PhxSnMe
- Smith, Stuart E.,Sasaki, Jennifer M.,Bergman, Robert G.,Mondloch, Joseph E.,Finke, Richard G.
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p. 1839 - 1841
(2008/09/17)
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- Molecular structure of propargylgermane (2-propynylgermane) determined by gas-phase electron diffraction and quantum chemical calculations
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The molecular structure of propargylgermane, HC≡CCH 2GeH3, has been determined by gas-phase electron diffraction. The electron-diffraction investigation has been supported by density functional theory and ab initio calculations. The
- Strenalyuk, Tatyana,Samdal, Svein,M?llendal, Harald,Guillemin, Jean-Claude
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p. 157 - 162
(2007/10/03)
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- Synthesis of novel terdentate N,C,N′-coordinated butyltin(IV) complexes and their redistribution reactions with SnCl4
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The Sn(IV) butyl complexes [BunSnCl3 - n(NCN)] (NCN = [C6H3(CH2NMe2)2-2,6] -, n = 1 (1), 2 (2), 3 (3)) were prepared. Spectroscopic analysis of 1-3 by 1H and 119Sn NMR gave evidence for the presence of intramolecular N → Sn interactions in solution. The molecular structure of 1, as determined by a single-crystal X-ray diffraction study, revealed that it contained a six-coordinate Sn(IV) center with intramolecular N → Sn coordination of both ortho-amine substituents. Addition of SnCl4 to 1 resulted in the isolation of the HCl adduct [BuSnCl3(NCN +H)] (6). Reactions of 2 and 3 with SnCl4 each resulted in the HCl salt [SnCl4(NCN+H)] (8) and the corresponding butyltin chloride, Bu2SnCl2 and Bu3SnCl, respectively. The formation of HCl adducts 6 and 8 was ascribed to transfer of the NCN ligand to SnCl4 and the presence of HCl (from partial hydrolysis of the product or SnCl4 during the work up procedure). The molecular structures of 6 and 8 have been determined through single-crystal X-ray diffraction and revealed the presence of a [BuSnCl3(aryl)] - or [SnCl4(aryl)]- stannate anion, respectively, with in each case one coordinated ortho-amine function and one protonated amine moiety involved in N-H?Cl-Sn hydrogen bonding in both compounds (2.14 ? for 6 and 2.18 ? for 8).
- Thoonen, Sander H.L.,Van Hoek, Hein,De Wolf, Elwin,Lutz, Martin,Spek, Anthony L.,Deelman, Berth-Jan,Van Koten, Gerard
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p. 1544 - 1553
(2007/10/03)
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- Dissociation of carbanions from acyl iridium compounds: An experimental and computational investigation
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Instead of reductive elimination of aldehyde, or decarbonylation to give a trifluoroalkyl hydride, heating Cp*(PMe3)Ir(H)[C(O)CF 3] (1) leads to the quantitative formation of Cp*(PMe 3)Ir(CO) (2) and CF3H. Kinetic experiments, isotope labeling studies, solvent effect studies, and solvent-inclusive DFT calculations support a mechanism that involves initial dissociation of trifluoromethyl anion to give the transient ion-pair intermediate [Cp*(PMe3)Ir(H) (CO)]+[CF3]-. Further evidence for the ability of CF3- to act as a leaving group came from the investigation of the analogous methyl and chloride derivatives Cp*(PMe3)Ir(Me)[C(O)CF3] and Cp*(PMe 3)Ir(Cl)[C(O)CF3], Both of these compounds undergo a similar loss of trifluoromethyl anion, generating an iridium carbonyl cation and CF3D in CD3OD. Three additional acyl hydrides, Cp*(PMe3)Ir-(H)[C(O)RF] (where RF = CF2CF3, CF2CF2CF3, or CF2(CF2)6CF3) undergo R F-H elimination to give 2 at a faster rate than CF3H elimination from 1. Stereochemical studies using a chiral acyl hydride with a stereocenter at the β-position reveal that ionization of the carbanion occurs to form a tight ion-pair with high retention of configuration and enantiomeric purity upon proton transfer from iridium.
- Cordaro, Joseph G.,Bergman, Robert G.
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p. 16912 - 16929
(2007/10/03)
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- Convenient syntheses of aryl and perfluoroaryl trichlorogermanes and germatranes via an organotin route
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Aryl- and (perfluoroaryl)trichlorogermanes ArGeCl3(Ar = C 6H5, 2-FC6H4, 3,5-(CF 3)2C6H3, C6F5, 2,3,5,6-F4C5N) are easily obtained in 60-80% yields from the corresponding tributyl-stannanes and GeCl4 (1:1) at 150 °C in the absence of a solvent. Although the tin-to-germanium transmetalation of C6F5 group is sluggish, it is facilitated by addition of 1-2 mol % AIBN (2,2′-azobis(isobutyronitrile)).
- Kultyshev, Roman G.,Prakash, G.K. Surya,Olah, George A.,Faller, Jack W.,Parr, Jonathan
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p. 3184 - 3188
(2008/10/09)
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- Synthesis of (Methyl-β-cyanoethyl)cyclosiloxanes
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Previously unknown (methyl-β-cyanoethyl)tri-, -tetra-, and -pentacyclosiloxanes were prepared by oxygen-halogen exchange between silicon and tin. The 29Si NMR spectra of the products were measured and interpreted.
- Zuev,Kalinin
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p. 546 - 549
(2007/10/03)
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- Generation of organotantalum reagents and conjugate addition to enones
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A superior method of conjugate allylation: The transmetalation of allyltin compounds with TaCl5 yielded active tantalum reagents for conjugate addition to enones. Even bulky allyl moieties could be introduced to enones in this manner (see scheme). Both cyclic and acyclic enones reacted facilely under extremely mild conditions.
- Shibata, Ikuya,Kano, Takeyoshi,Kanazawa, Nobuaki,Fukuoka, Shoji,Baba, Akio
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p. 1389 - 1392
(2007/10/03)
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- Copper(II)/tin(II) reagent for allylation, propargylation, alkylatipn, and benzylation of disulfides and elemental sulfur: New insight into the "copper effect"
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Organic bromides and iodides react with diorganodisulfides in the presence of stannous chloride and catalytic cupric halide, giving rise to corresponding unsymmetrical sulfides. Similar reactions but with elemental sulfur provide trisulfides and tetrasulf
- Sinha, Pradipta,Kundu, Abhijit,Roy, Sujit,Prabhakar, Sripadi,Vairamani,Sankar, A. Ravi,Kunwar
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p. 157 - 162
(2008/10/08)
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- Synthesis, structure and catalytic application of palladium(II) complexes bearing N-heterocyclic carbenes and phosphines
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A variety of mixed palladium(II) complexes bearing N-heterocyclic carbenes (NHCs) and triaryl- and trialkylphosphines [NHC(R2)]Pd(PR′3)I2 (R=Me, t-Bu, (R)-1-phenylethyl; R′=Ph, o-tolyl, cyclohexyl, t-Bu) have been prepared. Crystal structure details of trans-diiodo(1,3-di-tert-butylimidazolin-2-ylidene)(triphenylphosphino) palladium(II) are presented. The complexes were tested as catalysts in the Mizoroki-Heck, Suzuki-Miyaura and Stille reactions as well as in the dimerization of phenylacetylene. In catalytic studies of the Suzuki-Miyaura cross-coupling reaction, the performance of these novel complexes was compared to the results obtained by the corresponding bis(NHC) and bis(phosphine) complexes.
- Herrmann, Wolfgang A.,B?hm, Volker P.W.,Gst?ttmayr, Christian W.K.,Grosche, Manja,Reisinger, Claus-Peter,Weskamp, Thomas
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p. 616 - 628
(2007/10/03)
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- Palladium complex-catalyzed germylation of allylic halides using (germyl)stannanes
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(Triethylgermyl)tributylstannane reacts metal-selectively with allylic halides at room temperature (r.t.) in the presence of tris(dibenzylideneacetone)dipalladium, Pd2(dba)3CHCl3, to provide an alternative route to allylge
- Nakano, Taichi,Ono, Kazuyoshi,Senda, Yoshiya,Migita, Toshihiko
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p. 313 - 317
(2007/10/03)
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- Efficient synthesis of γ-alkylidenetetronic esters by sequential lewis acid catalyzed [3 + 2] cyclizations and palladium-catalyzed cross-coupling reactions
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A new approach for the synthesis of γ-alkylidenetetronic acids and esters is reported which involves Me3SiOTf-catalyzed, regio- and stereoselective cyclization of 4-alkoxy-1,3-bis(trimethylsilyloxy)-1,3-butadienes with oxalyl chloride. The α-hydroxy group of the butenolides is efficiently functionalized by palladium-catalyzed cross-coupling reactions via the corresponding enol triflates.
- Langer,Eckardt,Schneider,Goebel,Herbst-Irmer
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p. 2222 - 2226
(2007/10/03)
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- Mechanistic studies on Pd-catalyzed telomerization and co-cyclization of butadiene: Amphiphilicity of bis-π-allylpalladium intermediate in the presence of phosphine ligand
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Pd-catalyzed reactions of butadiene, which proceed through a bis-π-allylpalladium intermediate, (η3,η3-C8H12)Pd (2), were performed in the presence of both a pronucleophile (aceto- or cyanoacetate) and an electrophile (benzaldehyde). Methyl aceto- or cyanoacetate and benzaldehyde reacted independently with 2 to give telomers 8 and the divinylsubstituted pyranes 9, respectively. In the case of methyl cyanoacetate, the co-cyclization of 2 with 2-cyano-3-phenylpropenoate (11) formed in situ also took place to afford the cyclohexane derivative 10. Namely, three kinds of amphiphilic additions of the C8-chain of 2 occurred to δ+H-Nuδ-, δ+C=Cδ- and δ+C=Oδ- simultaneously in a one-pot reaction The Pd-catalyzed reaction of allyl chloride, allyltributylstannane, methyl cyanoacetate, and benzaldehyde was undertaken under neutral conditions, expecting the amphiphilic reactions by the intermediacy of (η3-C3H5)2Pd (6) formed in situ. Allylation of both benzaldehyde and methyl cyanoacetate took place. Competitively amphiphilic bis-allylation of the polar double bond of 11 also occurred to form the 1,7-octadiene derivative 18. The mechanisms of both reactions can be explainable in terms of the amphiphilicity of the intermediates (2 and 6) in the presence of a phosphine ligand.
- Kiji, Jitsuo,Okano, Tamon,Nomura, Takaaki,Saiki, Kayoko,Sai, Torei,Tsuji, Jiro
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p. 1939 - 1945
(2007/10/03)
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- Mechanism of the stille reaction. 2. Couplings of aryl triflates with vinyltributyltin. Observation of intermediates. A more comprehensive scheme
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The mechanism of the [PdL4]-catalyzed couplings between R-OTf (R = pentahalophenyl; L = PPh3, AsPh3) and Sn(CH = CH2)Bu3 has been studied. The addition of LiCl favors the coupling for L = AsPh3 in THF but retards it for L = PPh3. Separate experiments show that for L = AsPh3, LiCl accelerates the otherwise very slow and rate-determining oxidative addition of the aryl triflate to [PdL4], leading to trans-[PdRClL2]. Therefore, the overall process is accelerated. For L = PPh3, the rate-determining step is the transmetalation. Complex trans-[PdRXL2], with X = Cl, is formed in the presence of LiCl, whereas an equilibrium mixture mainly involving species with X = TfO, L, or S (S = solvent) is established in the absence of LiCl. Since the transmetalation is slower for X = Cl than for the other complexes, the overall process is retarded by addition of LiCl. The transmetalation in complexes trans-[PdRXL2], with X = Cl, follows the S(E)2(cyclic) mechanism proposed in Part 1 (Casado, A. L.; Espinet, P. J. Am. Chem. Soc. 1998, 120, 8978-8985), giving the coupling product R-CH=CH2'directly. For X = TfO or L, rather stable intermediates trans-[PdR(CH=CH2)L2] are detected, supporting an S(E)2(open) mechanism. The key intermediates undergoing transmetalation in the conditions and solvents most commonly used in the literature have been identified. The operation of S(E)2(cyclic) and S(E)2(open) pathways emphasizes common aspects of the Stille reaction with the Hiyama reaction where, using R2SiF3 that is chiral at the α-carbon of R2, retention or inversion at the transmetalated chiral carbon can be induced. This helps us to understand the contradictory stereochemical outcomes in the literature for Stille couplings using R2SnR3 derivatives that are chiral at the α-carbon of R2 and suggests that stereocontrol of the Stille reaction might be achieved.
- Casado,Espinet,Gallego
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p. 11771 - 11782
(2007/10/03)
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- Easy general method for interhalide conversions in organotin compounds
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The halides in organotin halides are easily interconverted in excellent yields using aqueous ammonium halide solutions and various organic solvents.
- Zobel, Bernhard,Lim, Allan E. K.,Dunn, Kerri,Dakternieks, Dainis
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p. 4889 - 4890
(2008/10/08)
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- Trichlorosilylation of chlorogermanes and chlorostannanes with HSiCl3/Net3 followed by base-catalysed formation of (Me3Ge)2Si(SiCl3)2 and related branched stannylsilanes
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Chlorotrimethylgermane 1 and dichlorodimethylgermane 4 react with trichlorosilane and triethylamine to provide trichlorosilylgermanes Me4-nGe(SiCl3)n (n = 1: 2; n = 2: 5) in fair yields, as distillable liquids. The formation of 2 is followed by base-catalysed decomposition reactions leading to novel solid (Me3Ge)2Si(SiCl3)2 3. Chlorotrialkylstannanes 6a-c (6a: R = CH3, 6b: R = C2H5, 6c: R = n-C4H9) react with trichlorosilane and triethylamine providing the branched silylstannanes (R3Sn)2Si(SiCl3)2 7a-c and traces of silylstannanes R3SnSiCl3 8a-c. Only 7a was isolated in a pure state. Heating 7a or crude 7b and 7c with benzyl chloride leads to the formation of benzyltrichlorosilane (10). The constitution of compounds 2, 3, 5 and 7a was confirmed by MS, NMR and analytical data. The structures of C6D6-solvated 3 and C6H6-solvated 7a were determined by X-ray diffraction, and shown to be isotypic.
- Mueller, Lars,Du Mont, Wolf-Walther,Ruthe, Frank,Jones, Peter G.,Marsmann, Heinrich C.
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p. 156 - 163
(2007/10/03)
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- Intermediates and products of the hexachlorodisilane cleavage of group 14 element phosphanes and amines - Molecular structure of di-tert- butyl(trichlorosilyl)phosphane in the gas phase determined by electron diffraction and ab Initio calculations
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Reactions of dialkyl(trimethylsilyl)phosphanes RR'PSiMe3 (1: R, R' = tBu; 3: R, R' = iPr; 5: R = iPr, R' = tBu) with Si2Cl6 provide stable trichlorosilylphosphanes RR'PSiCl3 (2, 4, 6); the reactions of silyl- and stannylamines of iPr2NMMe3 (M = Si: 11; M = Sn: 12) with Si2Cl6, however, provide the stable pentachlorodisilanylamine iPr2NSi2Cl5 (13). Heating of 1 with the technical mixture Me2(Cl)SiSiCl2Me/(MeCl2Si)2 yields the stable silylphosphane tBu2PSiMe2Cl (8) and the disilanylphosphane tBu2PSi(Me)(Cl)Si(Me)Cl2 (9). Methylation of 9 with MeLi gave tBu2PSi2Me5 10, which was isolated in a pure state. Reactions of tBu(iPr)PSiMe3 (5) and of organometal phosphanes tBu(iPr)PMR3 (14: M = Ge, R = Me; 17a-c: M = Sn; R = Me, Et, nBu) with Si2Cl6 were monitored by 31P, 29Si, and 119Sn NMR. - In the first step of these reactions, new tBu(iPr)PSi2Cl5 (7) is formed. 7 is accompanied by increasing amounts of tBu(iPr)PSiCl3 (6) and Me3GeSiCl3 (15)/(Me3Ge)2Si(SiCl3)2 (16) or traces of compounds R3SnSiCl3 (19a-c) that decompose providing (R3Sn)2Si(SiCl3)2 (18a-c) and nBu3SnSi(SiCl3)3 (20c). Subsequently, compounds 19a-c decompose providing increasing amounts of 18a-c. Stannylphosphane 17b is also cleaved by SiCl4 leading to 6 with liberation of Et3SnCl, whereas 17b is formed from the reaction of 5 with Et3SnCl under liberation of Me3SiCl. The suggestion of an extra stabilisation of P-Si bonds of trichlorosilylphosphanes was subjected to direct evidence through the structure determination of the trichlorosilylphosphane tBu2PSiCl3 (2) in the gas phase by electron diffraction. This crowded molecule has a 'normal' P-Si bond length of 225.0(12) pm; its C1 symmetric conformation with both tBu groups and the SiCl3 group twisted about 17°from the perfectly staggered positions, and with each of the three groups tilted about 6°away from each other, allows to reduce steric strain.
- Du Mont, Wolf-W.,Müller, Lars,Martens, Reiner,Papathomas, Paul M.,Smart, Bruce A.,Robertson, Heather E.,Rankin, David W. H.
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p. 1381 - 1392
(2007/10/03)
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- Organotin compounds containing a bulky (Me3Si)3C or related ligand. Crystal structures of {(Me3Si)3CMe(O2NO)Sn}2O, (PhMe2Si)3CSnMeCl2 and (PhMe2Si)3CSnCl3
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Some compounds having very bulky ligands, mainly (Me3Si)3C (denoted by Tsi) or (PhMe2Si)3C (denoted by Tpsi), attached to functional tin centres have been studied. Treatment of TsiSnR2Cl, R=Me or Ph, with one equivalent of ICl gave the corresponding chloride TsiSnRCl2, and use of an excess of ICl gave TsiSnCl3 in both cases. Reaction of either chloride with one equivalent of Br2 gave the dibromide TsiSnRBr2; when an excess of Br2 was used TsiSnMe2Cl still gave the dibromide but TsiSiPh2Cl gave the tribromide TsiSnBr3. Reaction of TsiSnMe2Br with AgSCN or Ag2O gave TsiSnMe2NCS and (TsiSnMe2)2O, respectively, but when the crude product from the reaction of TsiSnMeBr2 with AgNO3 was recrystallized from MeOH the nitrato-oxide {TsiMe(O2NO)Sn}2O was obtained. In a seemingly previously unreported type of reaction, the alkoxide TsiSnMe2OEt reacted with ICl, Br2, or I2 to give TsiSnMe2X, X=Cl, Br, or I, respectively, and Bu3SnOEt likewise reacted with ICl to give Bu3SnCl. The chlorides TsiSnMe2Cl and TsiSnMeCl2 gave the hydrides TsiSnMe2H and TsiSnMeH2 on treatment with LiAlH4, but in the case of TpsiSnMe2Cl the Tpsi-Sn bond was cleaved to give TpsiH. The compound (Me3Si)2C(SnMe2Ph)(SiMe2Cl) reacted with a 1 M proportion of AgBF4 in CH2Cl2 with cleavage of the Sn-Ph bond to give the difluoride (Me3Si)2C(SnMe2F)(SiMe2F). The crystal structures of the monomeric compounds {TsiMe(O2NO)Sn}2O, TpsiSnMeCl2 and TpsiSnCl3 are reported; {TsiMe(O2NO)Sn}2O provides the first example of unidentate bonding of an NO3 group to four-coordinate tin.
- Al-Juaid, Salih S.,Al-Rawi, Mustafa,Eaborn, Colin,Hitchcock, Peter B.,Smith, J. David
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p. 215 - 226
(2007/10/03)
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- Mechanism of the Stille reaction. 1. The transmetalation step. Coupling of R1I and R2SnBu3 catalyzed by trans-[PdR1IL2] (R1 = C6Cl2F3; R2 = vinyl, 4-methoxyphenyl; L = AsPh3)
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The so far accepted mechanism of the Stille reaction (palladium- catalyzed cross-coupling of organotin reagents with organic electrophiles) is criticized. Based on kinetic studies on catalytic reactions, and on reactions with isolated intermediates, a corrected mechanism is proposed. The couplings between R1I (1) (R1 = C6-Cl2F3 = 3,5-dichlorotrifluorophenyl) and R2SnBu3 (R2 = CH=CH2, 2a; C6H4-4-OCH3, 2b), catalyzed by trans- [PdR1I(AsPh3)2] (3a), give R1-R2 and obey a first-order law, r(obs) = a[3a][2a]/(b + [AsPh3]), with a = (2.31 ± 0.09) x 10-5 s-1 and b = (6.9 ± 0.3) x 10-4 mol L-1, for [1] = [2a] = 0-0.2 mol L-1, [3a] = 0-0.02 mol L-1, and [AsPh3] = 0-0.07 mol L-1, at 322.6 K in THF. The only organopalladium(II) intermediate detected under catalytic conditions is 3a. The apparent activation parameters found for the coupling of 1 with 2a support an associative transmetalation step (ΔH((±))(obs) = 50 ± 2 kJ mol-1, ΔS((±))(obs) = -155 ± 7 J K-1 mol-1 in THF; and ΔH((±))(obs) = 70.0 ± 1.7 kJ mol-1, ΔS((±))(obs) = -104 ± 6 J K-1 mol-1 in chlorobenzene, with [1]0 = [2]0 = 0.2 mol L-1, [3a] = 0.01 mol L-1). The reactions of 2a with isolated trans-[PdR1X(AsPh3)2 (X = halide) show rates Cl > Br > I. From these observations, the following mechanism is proposed: Oxidative addition of R1X to PdL(n) gives cis- [PdR1XL2], which isomerizes rapidly to trans[PdR1XL2]. This trans complex reacts with the organotin compound following a S(E)2 (cyclic) mechanism, with release of AsPh3 (which explains the retarding effect of the addition of L), to give a bridge intermediate [PdR1L(μ-X)(μ-R2)SnBu3]. In other words, an L-for-R2 substitution on the palladium leads R2 and R1 to mutually cis positions. From there the elimination of XXnBu3 yields a three- coordinate species cis-[PdR1R2L], which readily gives the coupling product R1-R2.
- Casado, Arturo L.,Espinet, Pablo
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p. 8978 - 8985
(2007/10/03)
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- Lewis acid mediated Diels-Alder reactions of 6-vinylpurines
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6-Vinylpurines readily undergo Diels-Alder reactions with dienes. Both reactivity and endo selectivity are greatly improved when the cycloadditions are performed in the presence of zinc chloride. Lewis acid mediated Diels-Alder reaction of 6-vinylpurine riboside was employed as a key step in the synthesis of a nucleoside with structural resemblance to potent A1 adenosine agonists.
- veras, Anniken T.,Gundersen, Lise-Lotte,Rise, Frode
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p. 1777 - 1786
(2007/10/03)
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- Reaction of Vanadocene with Cyanamide and Bis(tributylstannyl)carbodiimide
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Vanadocene [bis(η5-cyclopentadienyl)vanadium] was reacted with cyanamide to obtain previously unknown bis(η5-cyclopentadienyl)bis(cyanamido)vanadium. When exposed to air, the latter converts to (η5-cyclopentadienyl)bis(cyanamido)vanadium oxide. The reaction of vanadocene or its monochloride with bis(tributylstannyl)carbodiimide produces exclusively, regardless of the reactant ratio, bis[bis(η5-cyclopentadienyl)vanadium]carbodiimide which is readily oxidized in air with intermediate formation of bis(η5-cyclopentadienylvanadiumoxo)carbodiimide.
- Gordetsov,Zimina,Levakova,Kulagina
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p. 764 - 766
(2007/10/03)
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- Synthesis of Benzenesulfonyl Derivatives with N-Metal Bonds
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Reaction of p-NH2C6H4SO2NH2 with (Bu3Sn)2O was used to prepare p-Bu3SnNHC6H4SO2NHSnBu3, whose transmetalation with (η5-C5H5)2V(Cp2V) gave p-CpVNHC6H4SO2NHVCp. When exposed to air, the latter rapidly converted to p-O=VNHC6H4SO2NHVCp and then to the parent sulfonamide. Sulfonamides PhSO2NHMCp were synthesized in a similar way from PhSO2NHSnBu3 and Cp2M or Cp2MCl2 (M = V, Ti, Nb, Mo).
- Gordetsov,Latyaeva,Levakova,Zimina,Cherkasov,Kulagina,Kozina
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p. 780 - 784
(2007/10/03)
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- Synthesis and characterization of allylic dihaloboranes
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Volatile allylic dihaloboranes have been prepared and characterized by 1H, 11B, 13C, and 19F NMR spectroscopy and mass spectrometry. The stability (τ1/2) of such compounds in dilute CDCl3 solutions depends on the substituents and the halides and ranges from a few minutes (allylic dibromoboranes) to several days (allylic difluoroboranes). Allyldihaloborane etherates were obtained by addition of diethyl ether to the corresponding free allyldihaloborane.
- Le Serre, Stéphanie,Guillemin, Jean-Claude
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p. 5844 - 5848
(2008/10/08)
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- Synthesis of Aromatic and Olefinic Sodium Sulfonates by Electrophilic Destannylation with Trimethylsilyl Chlorosulfonate
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A mild and effective method for the preparation of a variety of aromatic, olefinic, and acetylenic sodium sulfonates is described.The reaction of trialkylaryl- (2a-k) and -heteroarylstannanes (4a-d), bis-(1-alkenyl)dibutylstannanes (6a-f), or trialkylakynylstannanes with trimethylsilyl chlorosulfonate (1) followed by hydrolysis with aqueous NaHCO3 provides the sodium sulfonates in an ipso-specific and in the case of vinylic stannanes stereospecific manner.A comparision of the reactivity of stannylated and silylated olefinic compounds 13 and 14 underlines the greater leaving ability of the stannyl moiety.The in situ preparation of the stannanes makes it possible to apply the synthetic method to natural products such as N-substituted apocodeine (17). - Key Words: Electrophilic aromatic substitution/ Electrophilic vinylic substitution/ Trialkylstannanes, application of/ Arylsulfonates, sodium salts of/ Vinylsulfonates, sodium salts of
- Niestroj, Michael,Lube, Andreas,Neumann, Wilhelm P.
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p. 575 - 580
(2007/10/02)
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- Primary vinyl- and alkynylstibines: Preparation and characterization
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Primary unsaturated stibines ethenylstibine (1a), E-prop-1-enylstibine (1b), ethynylstibine (2a), and prop-1-ynylstibine (2b) are synthesized by reaction of antimony trichloride with the corresponding vinyltributylstannanes 3a,b and alkynyltributylstannanes 4a,b, respectively, followed by a chemoselective reduction of the formed dichlorostibines 5a,b and 6a,b. Compounds 1a,b and 2a,b are characterized on the basis of spectral data (NMR, photoelectron spectroscopy and high resolution mass spectrometry). In particular, the PE spectra display very well-resolved bands (1a, 9.3, 10.3, 11.2. 11.9, 13.7, and 15.0 eV; 2a, 9.7, 10.5, and 11.2eV). The α-unsaturated stibines exhibit a low stability at room temperature even in the presence of a solvent (τ1/2 ca. 1 h) and lead to the formation of oligomeric material or an antimony mirror on the wall of the flask. Attempts to detect C-Sb multiple bond derivatives by a base-catalyzed rearrangement of 1 or 2 were unsuccessful.
- Legoupy,Lassalle,Guillemin,Métail,Senio,Pfister-Guillouzo
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p. 1466 - 1471
(2008/10/08)
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- C-, N- and C,N-Organostannyl Tetrazoles: Synthesis, Characterisation and Reactivity
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Open-chain C,N-organostannyl tetrazoles, R2R'Sn(CH2)nCN4SnBu3 (n = 2 or 3, R2R' = Ph3; n = 2, R2R' = Bu2Ph), have been synthesized by a cycloaddition reaction between R3Sn(CH2)nCN and SnBu3(N3).Prolonged heating of the reaction mixture yields the novel bicyclic species C,N-R2Sn(CH2)nCN4 (n = 2 or 3, R = Ph; n = 2, R = Bu).The reaction chemistry of both classes of compound has been studied, along with a reinvestigation of the parent 5-organo(N-triorganostannyl)tetrazoles RCN4SnR'3, by 13C and 119Sn NMR spectroscopy.The crystal structure of 2,2-diphenyl-1,7,8,9-tetraaza-2-stannabicyclonona-6,8-diene has also been determined.
- Blunden, Stephen J.,Mahon, Mary F.,Molloy, Kieran C.,Waterfield, Philip C.
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p. 2135 - 2144
(2007/10/02)
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- Simple procedure for conversion of a trialkyltin fluoride into the corresponding chloride or bromide
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Trialkyltin fluorides are converted into the chlorides or bromides on treatment with an excess of the corresponding sodium halide in tetrahydrofuran.
- Mitchell, Terence N.,Kwetkat, Klaus,Godry, Bernd
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p. 1633 - 1634
(2008/10/08)
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- Comparison of the allylation reactions of aldehydes using allylstannanes with boron trifluoride etherate and boron trichloride
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Reactions between allylstannanes, R2CH=CHCHR1SnBu3 (R1 = R2 = H (4); R1 = H, R2 = Me (5); R1R2 = (CH2)3 (6) and aldehydes, RCHO (e.g.R = Et) in the presence of BF3OEt2 in CH2Cl2 at -78 deg C produce stereoselectively erythro-RCH(OH)CHR2CH=CHR1 (with one equivalent RCHO) and 4-OH-3-R1-5-R2-2,6-R2-tetrahydropyrans (with an excess of RCHO).In contrast, when BCl3 is used in place of BF3OEt2 the reactions give mixtures of chlorinated alkenes (both homoallyl chlorides and allyl chlorides) and 4-Cl-3-R1-5-R2-2,6-R2-tetrahydropyrans (3; X = Cl).Thus 5, EtCHO and BCl3 (all equimolar) provide EtCHClCH2CH=CHMe (51percent, (E) + (Z)), EtCHClCHMeCH=CH2 (7percent, erythro + threo), EtCH2CH=CH-CHMeCl (30percent, (E) + (Z)) and 3 (12percent, X = Cl); with EtCHO (2.2 equivalents). 3 (X = Cl; cis/trans = 70/30) becomes the sole product.The product, erythro-EtCHClCHCH=CH(CH2)2CH2 (97percent) was produced from equimolar EtCHO, BCl3 and 6; with excess EtCHO (2.2 equivalents), 9-Cl-2,4-Et2-cis-3-oxabicyclononane (17percent; cis/trans = 45/55) and erythro-EtCHClCHCH=CH(CH2)2CH2 (78percent) were obtained.
- Marton, Daniele,Tagliavini, Giuseppe,Zordan, Michele,Wardell, James L.
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p. 127 - 138
(2007/10/02)
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- Tritylation, Methoxymethylation, and Silylation of Allylic Hydroperoxides via Stannyl Peroxide Intermediates. Allylic Rearrangement of a Stannyl Peroxide
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Whereas primary and secondary allylic hydroperoxides are quantitatively converted by tributyltin methoxide into stannyl peroxides, whose treatment with trityl chloride, chloromethyl methyl ether, and t-butyldimethylsilyl trifluoromethane-sulphonate give the corresponding trityl, methoxymethyl, and silyl peroxides, a tertiary allylic hydroperoxide gives rearrangement products on stannylation and treatment with trityl chloride.
- Haynes, Richard K.,Vonwiller, Simone C.
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p. 448 - 449
(2007/10/02)
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- Iron(III)-induced Cleavage of Cyclic Allylic Hydroperoxides to Dicarbonyl Compounds under Aprotic Conditions
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Secondary and tertiary cyclic allylic hydroperoxides are rapidly cleaved by iron(III) catalysts in dichloromethane into dicarbonyl compounds.
- Haynes, Richard K.,Vonwiller, Simone C.
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p. 449 - 451
(2007/10/02)
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- Process for the fractional production of organotin compounds
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A process for the fractional production of mono-, di- or triorganotin oxides which comprises subjecting an organotin halide to hydrolysis, separating the hydrolysis reaction mixture into three layers, and thereby obtaining the desired organotin oxide-containing layer as a triorganotin oxide--containing layer substantially free of mono- and/or diorganotin oxide, a monoorganotin oxide-containing aqueous layer, or a diorganotin oxide-containing layer substantially free of mono- and/or triorganotin oxide, and then recovering the tri-, mono- or diorganotin oxides from the desired organotin oxide-containing layers.
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- Heterocyclic substituted-phenoxyalkylisoxazoles as antiviral useful agents
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Compounds of the formula STR1 wherein: Y is an alkylene bridge of 3-9 carbon atoms; Z is N or HC; R is hydrogen or lower-alkyl of 1-5 carbon atoms, with the proviso that when Z is N, R is lower-alkyl; R1 and R2 are hydrogen, halogen, lower-alkyl, lower-alkoxy, nitro, lower-alkoxycarbonyl or trifluoromethyl; and Het is selected from specified heterocyclic groups, are useful and antiviral agents, particularly against picornaviruses, including numerous strains of rhinovirus.
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- Process for preparing unsymetrical hydrocarbontin chlorides
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A process is described for preparing high purity unsymetrical hydrocarbontin chlorides in less than one hour at temperatures below 90° C. utilizing a combination catalyst-complexing agent resulting in yields above 98%.
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- On the Mechanism of SnCl4-Promoted Additions of Allylstannanes to Aldehydes: A Response to Denmark, Wilson and Willson
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The reaction of allyltri-n-butylstannane with the complexes formed from three aldehydes (1-3) with SnCl4 has been investigated via variable-temperature (119)Sn NMR spectroscopy under carefully controlled conditions.With aldehyde 1, which forms a tight bidentate chelate with SnCl4, addition products are produced without the intermediacy of the transmetalation product allyltrichlorostannane at 1:1 stoichiometry, as revealed by appropriate control experiments with this reagent.The same is true of 2:1 (aldehyde:SnCl4) complexes derived from 1 and 2 provided that such complexes are formed stoichiometrically at low temperature and free SnCl4 is not present.With 3, free SnCl4, chelate, and 2:1 complex are all in equilibrium at -80 to -90 deg C at 1:1 SnCl4:aldehyde stoichiometry, and transmetalation with free SnCl4 is an important component of the overall reaction pathway.Competition experiments between the chelate and the 2:1 complex derived from 1 reveal that the chelate is more reactive but that the rate difference is modest.In addition, a mechanistic/spectroscopic study of allylstannane additions to aldehydes reported recently by Denmark, Wilson, and Willson has been reinvestigated, and results contrary to those reported are presented.In particular, it is shown that transmetalation pathways involving conversion of allyltri-n-butylstannane to allyltrichlorostannane or diallyldichlorostannane prior to reaction with aldehyde 5 and 6 do not occur from stable 2:1 (RCHO)2*SnCl4 complexes at low temperature.The sensitivity of such experiments to experimental details is emphasized.
- Keck, Gary E.,Andrus, Merritt B.,Castellino, Stephen
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p. 8136 - 8141
(2007/10/02)
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- Preparatiions of chloro(diene)polyfluorophenylplatinum(II) complexes and the structure of chloro(dicyclopentadiene)-pentafluorophenylplatinum(II)
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The complexes, PtCl(diene)R (diene = hexa-1,5-diene (hex) or norbornadiene (nbd), R C6F5, p-HC6F4, or p-MeOC6F4; diene = diene = dicyclopentadiene (dcy), R = C6F5) have been prepared by reaction between equimolar amounts of PtCl2(diene) and Me3SnR in dichloromethane. Most reactions also gave some of the corresponding PtR2(diene) complex, which was readily separated by chromatography, and Pt(p-MeOC6F4)2(nbd) was obtained in high yield from PtCl2(nbd) and Me3Sn(p-MeOC6F4) when a 1 2 mole ratio was used. Attempts to prepare PtCl(dcy)R (R p-HC6F4 or p-MeOC6F4) from Me3SnR gave only PtR2(dcy) in boiling CH2Cl2 despite the use of 1 1 reactant stoichiometry, and Pt(p-MeOC6F4)2(dcy) or no reaction (R p-HC6F4) at room temperature. Alternative reagents, R′3 SnR (R′ Bu or Et, R C6F5 or p-MeOC6F4) had a variable effect on the selectivity of monoarylation. Thus, Bu3SnC6F5 was more selective and Et3SnC6F5 less selective in formation of PtCl(hex)C6F5 than Me3SnC6F5. With Et3SnR (R C6F5 or p-MeOC6F4) and an equimolar amount of PtCl2(dcy), PtCl(dcy)R was the major product. The crystal structure of ptCl(dcy)C6F5 shows near square planar stereochemistry for platinum and steric congestion. The double bond from the six-membered ring of dcy is unsymmetrically coordinated to platinum trans to C6F5 and is further from the metal than the other double bond, which is symmetrically bonded trans to chlorine. The pentafluorophenyl group is approximately normal to the coordination plane, and gives two ortho-fluorine resonances in the 19F NMR spectrum.
- Deacon,Gatehouse,Nelson-Reed
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p. 267 - 283
(2007/10/02)
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- PALLADIUM-CATALYZED REACTION OF ORGANIC HALIDES WITH ORGANOTIN COMPOUNDS INVOLVING OLEFIN INSERTION: SYNTHESIS OF 2,3-DISUBSTITUED NORBORNANES
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2,3-Disubstituted norbornanes were prepared by the palladium-catalyzed reaction of a ternary system composed of organic halide, organotin compound, and norbornene.The scope and limitations of this reaction are described.
- Kosugi, Masanori,Tamura, Hiroyuki,Sano, Hiroshi,Migita, Toshihiko
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p. 961 - 968
(2007/10/02)
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- Electron-transfer processes. 43. Attack of alkyl radicals upon 1-alkenyl and 1-alkynyl derivatives of tin and mercury
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Alkyl radicals, obtained by reaction of Bu3Sn? or ClHg? with alkylmercury halides, will undergo regioselective and in some cases stereospecific substitution by a free radical chain addition-elimination mechanism with 1-alkenylstannanes or -mercurials. The chain reaction is also observed for 1-alkynyl derivatives and in the photostimulated demercuration of mixed alkyl and 1-alkenyl- or 1-alkynylmercurials. Chain propagation with alkyl radical formation is also observed to occur in the reactions of β-eliminated ClHg? with Grignard reagents in PhH-THF solution. In competitive reactions of Bu3Sn? or ClHg? with pairs of alkylmercury chlorides, it is observed that a tert-butylmercurial is >1000 times more reactive than a n-butylmercurial, suggesting a concerted dissociate electron-transfer process not involving the intermediacy of RHg? species.
- Russell, Glen A.,Ngoviwatchai, Preecha,Tashtoush, Hasan I.
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p. 696 - 702
(2008/10/08)
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