- Surface organometallic chemistry on metals: Controlled hydrogenolysis of Me4Sn, Me3SnR, Me2SnR2, MeSnBu 3 and SnBu4 (R = methyl, n-butyl, tert-butyl, neopentyl, cyclohexyl) onto metallic rhodium supported on silica
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The controlled hydrogenolysis of MexSnR4-x (0 ≤ x ≤ 4; R = methyl, n-butyl, tert-butyl, neopentyl, cyclohexyl) onto Rh/SiO 2 is followed by quantitative and qualitative analysis of evolved gases. Only MeH and RH are detected in the evolved gases. There is hydrogenolysis of the Sn-C bonds without any C-C bond hydrogenolysis, leading to formation of grafted organometallic fragments. Using various organotin compounds, MexSnR4-x, it has been possible to determine the regioselectivity of the hydrogenolysis of the Sn-C bonds. The initial selectivity is inversely proportional to the steric bulk of the alkyl group: tBu xR4-x (symmetry D3h), in which the bulkiest group, e.g., R, is away from the surface could explain these results. This surface five-coordinate tin species could eliminate an alkyl group, generally a methyl group, thus decreasing the steric bulk around the tin, into the equatorial plane of D3h, via a concerted hydrogen transfer-elimination mechanism to give Rh-SnMex-1R4-x. Then, in the successive steps of the hydrogenolysis, the bulkiest group, R, would be eliminated.
- Taoufik, Mostafa,Cordonnier, Marie-Anne,Santini, Catherine C.,Basset, Jean-Marie,Candy, Jean-Pierre
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- Exploiting a beast in carbenoid chemistry: Development of a straightforward direct nucleophilic fluoromethylation strategy
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The first direct and straightforward nucleophilic fluoromethylation of organic compounds is reported. The tactic employs a fleeting lithium fluorocarbenoid (LiCH2F) generated from commercially available fluoroiodomethane. Precise reaction conditions were developed for the generation and synthetic exploitation of such a labile species. The versatility of the strategy is showcased in ca. 50 examples involving a plethora of electrophiles. Highly valuable chemicals such as fluoroalcohols, fluoroamines, and fluoromethylated oxygenated heterocycles could be prepared in very good yields through a single synthetic operation. The scalability of the reaction and its application to complex molecular architectures (e.g., steroids) are documented.
- Parisi, Giovanna,Colella, Marco,Monticelli, Serena,Romanazzi, Giuseppe,Holzer, Wolfgang,Langer, Thierry,Degennaro, Leonardo,Pace, Vittorio,Luisi, Renzo
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supporting information
p. 13648 - 13651
(2017/11/06)
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- Efficient Access to All-Carbon Quaternary and Tertiary α-Functionalized Homoallyl-type Aldehydes from Ketones
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β,γ-Unsaturated aldehydes with all-carbon quaternary or tertiary α-centers were rapidly assembled from ketones through a unique synthetic operation consisting of 1) C1 homologation, 2) Lewis acid mediated epoxide–aldehyde isomerization, and 3) electrophilic trapping. The synthetic equivalence of a vinyl oxirane and a β,γ-unsaturated aldehyde is the key concept of this previously undisclosed tactic. Mechanistic studies and labeling experiments suggest that an aldehyde enolate is a crucial intermediate. The homologating carbenoid formation plays a critical role in determining the chemoselectivity.
- Pace, Vittorio,Castoldi, Laura,Mazzeo, Eugenia,Rui, Marta,Langer, Thierry,Holzer, Wolfgang
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supporting information
p. 12677 - 12682
(2017/09/08)
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- METHOD FOR PRODUCING 14 GROUP METAL LITHIUM COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for quantitatively producing a group 14 metal lithium compound under a mild condition. SOLUTION: The method for producing a group 14 metal lithium compound represented by formula (4): R4-nMLin comprises reacting a compound represented by formula (1): R4-nMXn and lithium in the presence of a polycyclic aromatic compound represented by formula (2) or formula (3). [In formula (1) and formula (2), R is a hydrocarbon group; M is a metal atom selected from Si, Ge and Sn; X is a halogen atom or R3M- (R and M are the same as mentioned above); and n is 1 or 2] and [R1 is H or a hydrocarbon group; and m is an integer of 0 to 5.] SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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- Stannyl-Lithium: A Facile and Efficient Synthesis Facilitating Further Applications
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We have developed a highly efficient, practical, polycyclic aromatic hydrocarbon (PAH)-catalyzed synthesis of stannyl lithium (Sn-Li), in which the tin resource (stannyl chloride or distannyl) is rapidly and quantitatively transformed into Sn-Li reagent at room temperature without formation of any (toxic) byproducts. The resulting Sn-Li reagent can be stored at ambient temperature for months and shows high reactivity toward various substrates, with quantitative atom efficiency.
- Wang, Dong-Yu,Wang, Chao,Uchiyama, Masanobu
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supporting information
p. 10488 - 10491
(2015/09/28)
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- The Scope of Direct Alkylation of Gold Surface with Solutions of C1-C4 n-Alkylstannanes
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Treatment of cleaned gold surfaces with dilute tetrahydrofuran or chloroform solutions of tetraalkylstannanes (alkyl = methyl, ethyl, n-propyl, n-butyl) or di-n-butylmethylstannyl tosylate under ambient conditions causes a self-limited growth of disordered monolayers consisting of alkyls and tin oxide. Extensive use of deuterium labeling showed that the alkyls originate from the stannane and not from ambient impurities, and that trialkylstannyl groups are absent in the monolayers, contrary to previous proposals. Methyl groups attached to the Sn atom are not transferred to the surface. Ethyl groups are transferred slowly, and propyl and butyl rapidly. In all cases, tin oxide is codeposited in submonolayer amounts. The monolayers were characterized by ellipsometry, contact angle goniometry, polarization modulated IR reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy with ferrocyanide/ferricyanide, which revealed a very low charge-transfer resistance. The thermal stability of the monolayers and their resistance to solvents are comparable with those of an n-octadecanethiol monolayer. A preliminary examination of the kinetics of monolayer deposition from a THF solution of tetra-n-butylstannane revealed an approximately half-order dependence on the bulk solution concentration of the stannane, hinting that more than one alkyl can be transferred from a single stannane molecule. A detailed structure of the attachment of the alkyl groups is not known, and it is proposed that it involves direct single or multiple bonding of one or more C atoms to one or more Au atoms.
- Kaletová, Eva,Kohutová, Anna,Hajduch, Jan,Kaleta, Ji?í,Bastl, Zdeněk,Pospí?il, Lubomír,Stibor, Ivan,Magnera, Thomas F.,Michl, Josef
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p. 12086 - 12099
(2015/10/05)
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- On the configurational stability of chiral, nonracemic fluoro- and iodo-[D1]methyllithiums
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Enantiomerically pure fluoro-[D1]methyllithium and iodo-[D 1]methyllithiums of up to 92% ee were generated by transmetalation of the corresponding stannanes with MeLi in THF at various temperatures. The intermediate halo-[D1]methyllithiums were trapped with benzaldehyde or acetophenone already present in excess in the reaction mixture to either give halohydrins or to disintegrate to carbene. The fluoro-[D1] methyllithiums were found to be microscopically configurationally stable within the tested range of -95 to 0°C, but chemically only stable at temperatures below -95°C due to a rapidly increasing portion disintegrating to carbene. The iodo-[D1]methyllithiums were configurationally labile relative to the rate of addition to PhCHO at all temperatures tested (-95 to -30°C). Disintegration to carbene interfered as well. The microscopic configurational stability of enantiomerically pure fluoro-[D1]methyllithiums prepared by tin-lithium exchange in the presence of excess benzaldehyde or acetophenone has been investigated. Depending on the reaction temperature, a portion of the generated fluoro-[D1]methyllithiums was added to the electrophiles to give fluorohydrins; the remaining portions disintegrated to carbene and LiF (see scheme).
- Kail, Dagmar C.,Malova Krizkova, Petra,Wieczorek, Anna,Hammerschmidt, Friedrich
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p. 4086 - 4091
(2014/04/17)
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- Cine-Substitution in the Stille Coupling: Evidence for the Carbenoid Reactivity of sp3-gem-Organodimetallic Iodopalladio-trialkylstannylalkane Intermediates
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Two complementary routes to sp3-gem-organodimetallic iodopalladio-trialkylstannanylalkanes are presented. Such intermediates have been proposed as Pd-carbenoid precursors in the Busacca-Farina cine-substitution mechanism in the Stille coupling. The decomposition of iodomethyltrialkylstannanes by Pd(0) catalysts was monitored by 1H, 2D, and 119Sn NMR. The formation of ethylene, trace formaldehyde, and iodotrialkylstannanes was detected. When the reaction was carried out in the presence of norbornene, the corresponding cyclopropane was produced in good yield. These observations are consistent with the intermediacy of a Pd-carbenoid species. sp3-gem-Organodimetallic iodopalladio-trialkylstannanylalkane complexes were also prepared under stoichiometric conditions via transmetalation from tin to Pd(II). Me3SnCH2Sn(CH2CH2CH2)3 reacted with [(D-t-BPF)PdI]+I-, yielding the (D-t-BPF)Pd(II)ICH2SnMe3 complex that dimerized to form ethylene and cyclopropanated norbornene. The carbenoid reactivity of iodopalladio-trialkylstannanylalkanes complexes validates the Busacca-Farina mechanism of the cine-substitution in the Stille coupling. Copyright
- Fillion, Eric,Taylor, Nicholas J.
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p. 12700 - 12701
(2007/10/03)
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- Tin-magnesium transmetallation reactions
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Sulfur-functionalized methyltin compounds nBu3SnCH2S(O)iR (i = 0, 1, 2; R = Me, Ph) underwent transmetallation with Grignard compounds MgR′X (R′ = Me, nBu, Ph; X = Cl, Br, I) and diorganomagnesium compounds MgR′R″ (R′/R″ =
- Yousef, Rushdi I,Rüffer, Tobias,Schmidt, Harry,Steinborn, Dirk
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p. 111 - 114
(2007/10/03)
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- Wurtz-type reductive coupling reaction of primary alkyl iodides and haloorganotins in cosolvent/H2O(NH4Cl)/Zn media as a route to mixed alkylstannanes and hexaalkyldistannanes
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Mixed tetra-alkylstannanes R3SnR′ (R = Et, n-Pr, n-Bu and R′= Me, Et, n-Pr, n-Bu, n-Pent) and R2SnR′2 (R = n-Bu and R′ = Me, Et, n-Pr, n-Bu) can be easily prepared in a one-pot synthesis via coupling reaction of alkyl iodides R′I with R3SnX (X = Cl, I) and R2SnCl2 compounds in cosolvent-H2O(NH4Cl) medium mediated by zinc dust. Coupling also occurs with (Bu3Sn)2O. It has been verified that reactions are possible only with primary alkyl iodides; with secondary alkyl iodides the coupling reaction fails. When alkyl chlorides and bromides are used ditin compounds are obtained instead of the unsymmetrical tetra-alkylstannanes. This represents a route to hexaalkyldistannanes.
- Marton, Daniele,Tari, Massimo
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- Intracluster transmetalation of cuprates with stannanes
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Alkylarylcuprates with intramolecularly tethered stannanes undergo an intracluster Cu(I)/Sn(IV) transmetalation to yield arylstannanes.
- Mateo, Cristina,Cardenas, Diego J.,Martin-Matute, Belen,Echavarren, Antonio M.
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p. 2205 - 2206
(2007/10/03)
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- Reactions of Organoytterbium Compounds RYbI (R = Me, Et, Ph) with Organotin Oxides and Acetates
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Reactions of RYbI (R = Me, Et, Ph) with organotin oxides and acetates) involve cleavage of the Sn-O bonds to form tetrasubstituted stannanes mostly as single or main reaction products (yields 65-96 percent). A similar results was obtained in reaction of PhYbI with diphenyltin sulfide (yield 93 percent). However, reactions of RYbI (R = Me, Et, Ph) with Bu2SnO, followed by hydrolysis of the reaction mixtures lead to hydroxystannanoxanes Bu2RSnOH in 66-75 percent yields.
- Rybakova, L. F.,Syutkina, O. P.,Novgorodova, M. N.,Petrov, E. S.
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- Preparation of benzylstannanes by zinc-mediated coupling of benzyl bromides with organotin derivatives. Physicochemical characterization and crystal structures
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Benzyltrialkyl- (1-13) and benzyltriphenylstannanes (16-22) have been easily prepared in a one-pot synthesis via coupling reaction of benzyl bromide derivatives (C6H5CH2Br and XYC6H3CH2Br, X = H, Y = o-, m-, p-CH3, o-, m-, p-F, o-, m-Cl, and p-Br; X = o-F, Y = p-Br) with R3SnCl compounds (R = Et, Pr, Bu, and Ph) in THF/H2O (NH4Cl) medium mediated by zinc powder. Such coupling also occurs with (Bu3Sn)2O. Dibenzyldibutylstannane (15) is prepared by reaction of benzyl bromide with Bu2SnCl2 or (Bu2SnCl)2O, and (2-naphthylmethyl)tributylstannane (14) by reaction of 2-(bromomethyl)naphthalene with Bu3SnCl. 13C-and 119Sn-NMR data are reported for all compounds, and M?ssbauer data for benzyltributylstannanes 10 and 11 and benzyltriphenylstannanes 16-18 and 20-22. The crystal structures of Ph3SnBn, with Bn = o- (17) and m-ClC6H4CH2 (18) and o- (20) and m-FC6H4-CH2 (21) have been determined.
- Marton, Daniele,Russo, Umberto,Stivanello, Diego,Tagliavini, Giuseppe,Ganis, Paolo,Valle, Giovanni Carlo
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p. 1645 - 1650
(2008/10/08)
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- 6-substituted mycophenolic acid and derivatives
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The disclosed 6-substituted derivatives of mycophenolic acid are therapeutic agents advantageous in the treatment of disease states indicated for mycophenolic acid and/or mycophenolate mofetil.
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- Selective lithiation of 1-bromo-2-((trimethylstannyl)methyl)benzene: Synthesis of 1-bromo-2-(lithiomethyl)benzene, 1-lithio-2-((trimethylstannyl)methyl)benzene, and α,2-dilithiotoluene
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Reactions of 1-bromo-2-((trimethylstannyl)methyl)benzene (1) with n-butyllithium and tert-butyllithium have been investigated. With n-butyllithium in tetrahydrofuran (THF) at -70°C, the only observed process was lithium-tin exchange, yielding 1-bromo-2-(lithiomethyl)benzene (2). In contrast, lithium-halogen exchange occurred when 1 was treated with tert-butyllithium in diethyl ether at -80°C to give 1-lithio-2-((trimethylstannyl)methyl)benzene (3). α,2-Dilithiotoluene could be prepared in high yield from 3 and tert-butyllithium in either diethyl ether (room temperature) or THF (-80°C).
- De Boer, Henricus J. R.,Akkerman, Otto S.,Bickelhaupt, Friedrich
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p. 2898 - 2903
(2008/10/08)
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- Cyclopenteneheptenoic acid derivatives and method of preparation thereof
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This invention relates to a novel cyclopenteneheptenoic acid derivative having the following formula STR1 wherein R1 is hydrogen, --COCH3, --COCF3, --CO--phenyl, or a hydroxyl protecting group such as tetrahydropyranyl, tetrahydrofuranyl, or tri-lower alkylsilyl; wherein R2 is --CH2 OR1, --COOH, --COOR, --CHO, --CH2 --OSi(R12)3, STR2 wherein R is lower alkyl and each R12 is independently lower alkyl or aryl; and wherein Y is ethylene, cis-vinylene, trans-vinylene, or acetylene. Also disclosed is a novel process for preparation of the above-defined cyclopenteneheptenoic acid derivative. This process involves coupling of a higher order cuprate complex with a chiral cyclopentene compound. The resultant product is particularly useful as a starting compound for high yield synthesis of optically active prostaglandins.
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- Preparation of Perfluoroalkyl Ketones by the Reaction of Perfluoroalkyllithiums with Esters
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A variety of esters react with perfluoroalkyllithiums in situ generated from perfluoroalkyl iodides and methyllithium to give perfluoroalkyl ketones in good yields.Perfluoroalkyllithiums add to α,β-unsaturated esters only in the 1,2-addition mode even in the presence of copper salt.Exception was observed in the reaction with maleates where perfluoroalkylated succinic esters and normal 1,2-addition products are obtained in comparable amounts.
- Uno, Hidemitsu,Shiraishi, Yasukazu,Suzuki, Hitomi
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p. 2636 - 2642
(2007/10/02)
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- Preparation and properties of unsymmetrical tetraorganotin compounds
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Unsymmetrical tetraorganotins, R2R1R2Sn (R=Me, R1=Bu, R2=Pe (Pe=pentyl) or Ph; R=Bu, R1=Pe, R2=Ph or Me; R=Pe, R1=Bu, R2=Me or Ph), BunR4-nSn (n=1-3, R=Me or Pe) and Pe2R2Sn (R=Me or Ph) have been synthesised.Various physical properties, including mass spectra, 1H and 13C NMR spectra, are reported.
- Marr, Iain L.,Rosales, Daniel,Wardell, James L.
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- Palladium Catalyzed Reaction of Acyltins with Organic Halides
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Palladium catalyzed reaction of acyltins with organic halides were investigated.Among the halides, acyl halides and allylic halides were good substrates, and the latter gave allylic ketones in good yields.
- Kosugi, Masanori,Naka, Hiroyuki,Harada, Saburo,Sano, Hiroshi,Migita, Toshihiko
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p. 1371 - 1372
(2007/10/02)
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- Retentive Stereospecificity in Deoxygenation of Epoxides with Sn-Al Reagents
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Reaction of epoxides with 3SnAlMe3>(1-)*Li(1+) affords β-oxido stannanes which collapse to alkene with overall retention of stereochemistry.The SN2 type ring opening of epoxides by tributylstannyl anion followed by anti elimination of Bu3Sn and OAl-Me3 groups explains the stereochemical results.The method can be succesfully applied to hydroxy epoxides derived from (E)-2-nonen-1-ol.The deoxygenation of epoxides with PhMe2SiAlEt2 also provides olefins of the same geometry as epoxides.
- Matsubara, Seijiro,Nonaka, Tsuyoshi,Okuda, Yasuhiro,Kanemoto, Shigekazu,Oshima, Koichiro,Nozaki, Hitosi
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p. 1480 - 1483
(2007/10/02)
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- Nucleophilicity vs. basicity in reactions of n-butyllithium and tert-butyllithium with tetramethylstannane
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The reactions of n-butyllithium and tert-butyllithium with tetramethylstannane have been examined with the objective of determining the degree of competition between proton abstraction from the methyl groups and nucleophilic displacement of these groups f
- Farah, Dan,Karol, Thomas J.,Kuivila, Henry G.
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p. 662 - 666
(2008/10/08)
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